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Di Stadio A, Ralli M, Kaski D, Koohi N, Gioacchini FM, Kysar JW, Lalwani AK, Warnecke A, Bernitsas E. Exploring Inner Ear and Brain Connectivity through Perilymph Sampling for Early Detection of Neurological Diseases: A Provocative Proposal. Brain Sci 2024; 14:621. [PMID: 38928621 PMCID: PMC11201480 DOI: 10.3390/brainsci14060621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 06/17/2024] [Accepted: 06/19/2024] [Indexed: 06/28/2024] Open
Abstract
Recent evidence shows that it is possible to identify the elements responsible for sensorineural hearing loss, such as pro-inflammatory cytokines and macrophages, by performing perilymph sampling. However, current studies have only focused on the diagnosis of such as otologic conditions. Hearing loss is a feature of certain neuroinflammatory disorders such as multiple sclerosis, and sensorineural hearing loss (SNHL) is widely detected in Alzheimer's disease. Although the environment of the inner ear is highly regulated, there are several communication pathways between the perilymph of the inner ear and cerebrospinal fluid (CSF). Thus, examination of the perilymph may help understand the mechanism behind the hearing loss observed in certain neuroinflammatory and neurodegenerative diseases. Herein, we review the constituents of CSF and perilymph, the anatomy of the inner ear and its connection with the brain. Then, we discuss the relevance of perilymph sampling in neurology. Currently, perilymph sampling is only performed during surgical procedures, but we hypothesize a simplified and low-invasive technique that could allow sampling in a clinical setting with the same ease as performing an intratympanic injection under direct visual check. The use of this modified technique could allow for perilymph sampling in people with hearing loss and neuroinflammatory/neurodegenerative disorders and clarify the relationship between these conditions; in fact, by measuring the concentration of neuroinflammatory and/or neurodegenerative biomarkers and those typically expressed in the inner ear in aging SNHL, it could be possible to understand if SNHL is caused by aging or neuroinflammation.
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Affiliation(s)
- Arianna Di Stadio
- Department GF Ingrassia, University of Catania, 95131 Catania, Italy
- Sense Research Unit, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (D.K.); (N.K.)
| | - Massimo Ralli
- Organ of Sense Department, University La Sapienza, 00185 Rome, Italy;
| | - Diego Kaski
- Sense Research Unit, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (D.K.); (N.K.)
| | - Nehzat Koohi
- Sense Research Unit, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (D.K.); (N.K.)
| | - Federico Maria Gioacchini
- Ear, Nose, and Throat Unit, Department of Clinical and Molecular Sciences, Polytechnic University of Marche, 60020 Ancona, Italy;
| | - Jeffrey W. Kysar
- Otolaryngology—Head and Neck Department, Columbia University, New York, NY 10032, USA; (J.W.K.); (A.K.L.)
| | - Anil K. Lalwani
- Otolaryngology—Head and Neck Department, Columbia University, New York, NY 10032, USA; (J.W.K.); (A.K.L.)
| | - Athanasia Warnecke
- Department of Otolaryngology—Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany;
| | - Evanthia Bernitsas
- Multiple Sclerosis Center, Neurology Department, Wayne State University, Detroit, MI 48201, USA;
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Razmovski T, Brody KM, Stathopoulos D, Zhang D, Cho E, Hampson AJ, Collins A, Bester C, O'Leary S. Intra-cochlear Flushing Reduces Tissue Response to Cochlear Implantation. Laryngoscope 2024; 134:1410-1416. [PMID: 37694764 DOI: 10.1002/lary.31022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/02/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
INTRODUCTION Intraoperative trauma leading to bleeding during cochlear implantation negatively impacts residual hearing of cochlear implant recipients. There are no clinical protocols for the removal of blood during implantation, to reduce the consequential effects such as inflammation and fibrosis which adversely affect cochlear health and residual hearing. This preclinical study investigated the implementation of an intra-cochlear flushing protocol for the removal of blood. METHODS Three groups of guinea pigs were studied for 28 days after cochlear implantation; cochlear implant-only (control group); cochlear implant with blood injected into the cochlea (blood group); and cochlear implant, blood injection, and flushing of the blood from the cochlea intraoperatively (flush group). Auditory brainstem responses (ABRs) in addition to tissue response volumes were analyzed and compared between groups. RESULTS After implantation, the blood group exhibited the highest ABR thresholds when compared to the control and flush group, particularly in the high frequencies. On the final day, the control and blood group had similar ABR thresholds across all frequencies tested, whereas the flush group had the lowest thresholds, significantly lower at 24 kHz than the blood and control group. Analysis of the tissue response showed the flush group had significantly lower tissue responses in the basal half of the array when compared with the blood and control group. CONCLUSIONS Flushing intra-cochlear blood during surgery resulted in better auditory function and reduced subsequent fibrosis in the basal region of the cochlea. This finding prompts the implementation of a flushing protocol in clinical cochlear implantation. LEVEL OF EVIDENCE N/A Laryngoscope, 134:1410-1416, 2024.
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Affiliation(s)
- Tayla Razmovski
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Kate M Brody
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Dimitra Stathopoulos
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Dongcheng Zhang
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Ellie Cho
- Biological Optical Microscopy Platform, University of Melbourne, Parkville, Victoria, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Aaron Collins
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Christofer Bester
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Stephen O'Leary
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
- The Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
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3
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Lue PY, Oliver MH, Neeff M, Thorne PR, Suzuki-Kerr H. Sheep as a large animal model for hearing research: comparison to common laboratory animals and humans. Lab Anim Res 2023; 39:31. [PMID: 38012676 PMCID: PMC10680324 DOI: 10.1186/s42826-023-00182-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023] Open
Abstract
Sensorineural hearing loss (SNHL), caused by pathology in the cochlea, is the most common type of hearing loss in humans. It is generally irreversible with very few effective pharmacological treatments available to prevent the degenerative changes or minimise the impact. Part of this has been attributed to difficulty of translating "proof-of-concept" for novel treatments established in small animal models to human therapies. There is an increasing interest in the use of sheep as a large animal model. In this article, we review the small and large animal models used in pre-clinical hearing research such as mice, rats, chinchilla, guinea pig, rabbit, cat, monkey, dog, pig, and sheep to humans, and compare the physiology, inner ear anatomy, and some of their use as model systems for SNHL, including cochlear implantation surgeries. Sheep have similar cochlear anatomy, auditory threshold, neonatal auditory system development, adult and infant body size, and number of birth as humans. Based on these comparisons, we suggest that sheep are well-suited as a potential translational animal model that bridges the gap between rodent model research to the clinical use in humans. This is especially in areas looking at changes across the life-course or in specific areas of experimental investigation such as cochlear implantation and other surgical procedures, biomedical device development and age-related sensorineural hearing loss research. Combined use of small animals for research that require higher throughput and genetic modification and large animals for medical translation could greatly accelerate the overall translation of basic research in the field of auditory neuroscience from bench to clinic.
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Affiliation(s)
- Po-Yi Lue
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand
| | - Mark H Oliver
- Liggins Institute, The University of Auckland, Auckland, New Zealand
- Ngapouri Research Farm Laboratory, University of Auckland, Waiotapu, New Zealand
| | - Michel Neeff
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Department of Surgery, Auckland District Health Board, Auckland, New Zealand
| | - Peter R Thorne
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand
- Section of Audiology, The University of Auckland, Auckland, New Zealand
| | - Haruna Suzuki-Kerr
- Department of Physiology, The University of Auckland, Auckland, New Zealand.
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand.
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Razmovski T, Collins A, Bester C, O'Leary S. Using Four-Point Impedance to Detect and Locate Blood during Cochlear Implantation . ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083677 DOI: 10.1109/embc40787.2023.10340312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Biosensing technologies are emerging as an important consideration when designing implantable medical devices. For cochlear implants, biosensors may help preserve the natural hearing a patient has prior to implantation by detecting blood in the cochlea during insertion. If blood enters the cochlea, it creates a hostile environment leading to further hearing loss and reduced device function. Here we present four-point impedance, measured directly from a commercial cochlear implant, as a biosensor for real-time detection of blood in the cochlea. The four-point impedance of different concentrations of whole blood in saline were measured using the impedance-measuring capabilities of a cochlear implant with a square-wave stimulation. Impedance derived from a cochlear implant succeeded in differentiating concentrations of blood in saline with results from a sensitivity analysis showing the lowest concentration the system could detect was between 12 % to 21 % of whole blood. In a subsequent in-vitro study, continuous four-point impedance was measured from a cochlear implant while it was inserted into a 3D printed cochlear model, followed by an injection of blood to emulate surgical events. These results demonstrated four-point impedance from a cochlear implant can instantaneously detect the addition of blood within the cochlea and localize it along the electrode array. The adaptation of a biosensing tool using a cochlear implant provides more information that can be relayed to the surgeon intraoperatively to potentially enhance hearing outcomes with the implant.Clinical Relevance - Using the cochlear implant itself to detect intra-cochlear bleeding may open therapeutic avenues to prevent further hearing loss.
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Kaderbay A, Berger F, Bouamrani A, Bidart M, Petre G, Baguant A, Giraud L, Schmerber S. Perilymph metabolomic and proteomic MALDI-ToF profiling with porous silicon chips: a proof-of-concept study. Hear Res 2022; 417:108457. [DOI: 10.1016/j.heares.2022.108457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 01/16/2022] [Accepted: 01/27/2022] [Indexed: 11/30/2022]
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Blanc F, Bemelmans AP, Affortit C, Joséphine C, Puel JL, Mondain M, Wang J. A Single Cisterna Magna Injection of AAV Leads to Binaural Transduction in Mice. Front Cell Dev Biol 2022; 9:783504. [PMID: 35087833 PMCID: PMC8787364 DOI: 10.3389/fcell.2021.783504] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Viral-mediated gene augmentation, silencing, or editing offers tremendous promise for the treatment of inherited and acquired deafness. Inner-ear gene therapies often require a safe, clinically useable and effective route of administration to target both ears, while avoiding damage to the delicate structures of the inner ear. Here, we examined the possibility of using a cisterna magna injection as a new cochlear local route for initiating binaural transduction by different serotypes of the adeno-associated virus (AAV2/8, AAV2/9, AAV2/Anc80L65). The results were compared with those following canalostomy injection, one of the existing standard inner ear local delivery routes. Our results demonstrated that a single injection of AAVs enables high-efficiency binaural transduction of almost all inner hair cells with a basal-apical pattern and of large numbers of spiral ganglion neurons of the basal portion of the cochlea, without affecting auditory function and cochlear structures. Taken together, these results reveal the potential for using a cisterna magna injection as a local route for binaural gene therapy applications, but extensive testing will be required before translation beyond mouse models.
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Affiliation(s)
- Fabian Blanc
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France.,CHRU Montpellier-Centre Hospitalier Régional Universitaire, Montpellier, France
| | - Alexis-Pierre Bemelmans
- Molecular Imaging Research Center, Institut de Biologie François Jacob, Direction de la Recherche Fondamentale, CEA, Fontenay-aux-Roses, France.,Université Paris-Saclay, CEA, CNRS, Laboratoire des Maladies Neurodégénératives, mécanismes, thérapies, imagerie, Fontenay-aux-Roses, France
| | - Corentin Affortit
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Charlène Joséphine
- Molecular Imaging Research Center, Institut de Biologie François Jacob, Direction de la Recherche Fondamentale, CEA, Fontenay-aux-Roses, France.,Université Paris-Saclay, CEA, CNRS, Laboratoire des Maladies Neurodégénératives, mécanismes, thérapies, imagerie, Fontenay-aux-Roses, France
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Michel Mondain
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France.,CHRU Montpellier-Centre Hospitalier Régional Universitaire, Montpellier, France
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France.,CHRU Montpellier-Centre Hospitalier Régional Universitaire, Montpellier, France
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Peter MS, Warnecke A, Staecker H. A Window of Opportunity: Perilymph Sampling from the Round Window Membrane Can Advance Inner Ear Diagnostics and Therapeutics. J Clin Med 2022; 11:jcm11020316. [PMID: 35054010 PMCID: PMC8781055 DOI: 10.3390/jcm11020316] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 12/29/2021] [Accepted: 01/06/2022] [Indexed: 12/12/2022] Open
Abstract
In the clinical setting, the pathophysiology of sensorineural hearing loss is poorly defined and there are currently no diagnostic tests available to differentiate between subtypes. This often leaves patients with generalized treatment options such as steroids, hearing aids, or cochlear implantation. The gold standard for localizing disease is direct biopsy or imaging of the affected tissue; however, the inaccessibility and fragility of the cochlea make these techniques difficult. Thus, the establishment of an indirect biopsy, a sampling of inner fluids, is needed to advance inner ear diagnostics and allow for the development of novel therapeutics for inner ear disease. A promising source is perilymph, an inner ear liquid that bathes multiple structures critical to sound transduction. Intraoperative perilymph sampling via the round window membrane of the cochlea has been successfully used to profile the proteome, metabolome, and transcriptome of the inner ear and is a potential source of biomarker discovery. Despite its potential to provide insight into inner ear pathologies, human perilymph sampling continues to be controversial and is currently performed only in conjunction with a planned procedure where the inner ear is opened. Here, we review the safety of procedures in which the inner ear is opened, highlight studies where perilymph analysis has advanced our knowledge of inner ear diseases, and finally propose that perilymph sampling could be done as a stand-alone procedure, thereby advancing our ability to accurately classify sensorineural hearing loss.
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Affiliation(s)
- Madeleine St. Peter
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS 66160, USA;
| | - Athanasia Warnecke
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, D-30625 Hanover, Germany;
| | - Hinrich Staecker
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS 66160, USA;
- Correspondence:
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Triamcinolone acetonide can be detected in cerebrospinal fluid after intratympanic injection. Eur J Pharm Biopharm 2021; 170:52-58. [PMID: 34864199 DOI: 10.1016/j.ejpb.2021.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 10/30/2021] [Accepted: 11/28/2021] [Indexed: 11/21/2022]
Abstract
Intratympanically applied treatments are of increasing interest to the otologic community to treat sudden sensorineural hearing loss or vestibular disorders but also to deliver gene therapy agents, or biologics to the inner ear. Further diversion from the middle ear and perilymph to blood circulation and cerebrospinal fluid via the cochlear aqueduct are one of the limiting factors and so far not understood well enough. In this study, intratympanically applied triamcinolone acetonide was determined in cerebrospinal fluid. Additionally, perilymph was sampled through the round window membrane as well as at the lateral semicircular canal to determine drug levels. Of the twenty-one included patients, triamcinolone acetonide was quantifiable in cerebrospinal fluid in 43% at very low levels (range 0 ng/ml - 6.2 ng/ml) which did not correlate with perilymph levels. Drug levels at the two different perilymph sampling sites were within a range of 13.5 ng/ml to 1180.0 ng/ml. Results suggest an equal distribution of triamcinolone acetonide to semicircular canals, which might support the use of triamcinolone acetonide as a treatment option for vestibular pathologies such as Menièrés disease. On the other hand, the distribution to cerebrospinal fluid might be limiting current approaches in gene therapy where a central distribution is unwanted.
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Alimohammadi S, Kiani MA, Imani M, Rafii-Tabar H, Sasanpour P. A proposed implantable voltammetric carbon fiber-based microsensor for corticosteroid monitoring by cochlear implants. Mikrochim Acta 2021; 188:357. [PMID: 34595588 DOI: 10.1007/s00604-021-04994-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/22/2021] [Indexed: 01/12/2023]
Abstract
A novel carbon fiber microsensor (CFMS) with the capability of being inserted in the cochlear implant structure is introduced for in situ measurement of corticosteroid concentration. The microsensor structure is composed of a carbon microfiber, an Ag wire, and a Pt wire acting respectively as a working electrode, a reference electrode, and a counter electrode. In addition, a silicone septum is used for isolation purposes in place of the epoxy resin. The septum-insulated microsensor is capable of monitoring the concentration of the corticosteroids in the perilymph fluid without a need for sampling from the inner ear fluid and the consequent ex vivo analysis. The electrochemical determination of the corticosteroids was investigated on the carbon fiber electrode surface by differential pulse voltammetry. During the reduction of dexamethasone (DEX), a cathodic peak with a peak potential of -1.3 V appeared at the CFMS. Using the CFMS under optimized conditions, a calibration plot of the dexamethasone (DEX) in the artificial perilymph solution exhibited two linear ranges from 10 nM to 2 μM and 2 to 40 μM (sensitivity equal to 16.55 μA μM-1 cm-2; LOD = 4 nM) conforming with the DEX concentration range inside the inner ear after the insertion of a drug-eluting cochlear implant electrode (CIE). Furthermore, the interferences occurring in the hearing functions of the CIE after the presence and function of the CFMS were simulated numerically using the finite element method. According to our results, decreasing the size of the microsensor introduces lower interferences with the auditory function of the cochlear implant electrode.
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Affiliation(s)
- Somayeh Alimohammadi
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Kiani
- Chemistry & Chemical Engineering Research Center of Iran, Tehran, 14335-186, Iran.
| | - Mohammad Imani
- Department of Novel Drug Delivery Systems, Iran Polymer and Petrochemical Institute, Tehran, Iran.
| | - Hashem Rafii-Tabar
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- The Physics Branch of the Iran Academy of Sciences, Tehran, Iran
| | - Pezhman Sasanpour
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Jaudoin C, Carré F, Gehrke M, Sogaldi A, Steinmetz V, Hue N, Cailleau C, Tourrel G, Nguyen Y, Ferrary E, Agnely F, Bochot A. Transtympanic injection of a liposomal gel loaded with N-acetyl-L-cysteine: A relevant strategy to prevent damage induced by cochlear implantation in guinea pigs? Int J Pharm 2021; 604:120757. [PMID: 34058306 DOI: 10.1016/j.ijpharm.2021.120757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 01/17/2023]
Abstract
Patients with residual hearing can benefit from cochlear implantation. However, insertion can damage cochlear structures and generate oxidative stress harmful to auditory cells. The antioxidant N-acetyl-L-cysteine (NAC) is a precursor of glutathione (GSH), a powerful endogenous antioxidant. NAC local delivery to the inner ear appeared promising to prevent damage after cochlear implantation in animals. NAC-loaded liposomal gel was specifically designed for transtympanic injection, performed both 3 days before and on the day of surgery. Hearing thresholds were recorded over 30 days in implanted guinea pigs with and without NAC. NAC, GSH, and their degradation products, N,N'-diacetyl-L-cystine (DiNAC) and oxidized glutathione (GSSG) were simultaneously quantified in the perilymph over 15 days in non-implanted guinea pigs. For the first time, endogenous concentrations of GSH and GSSG were determined in the perilymph. Although NAC-loaded liposomal gel sustained NAC release in the perilymph over 15 days, it induced hearing loss in both implanted and non-implanted groups with no perilymphatic GSH increase. Under physiological conditions, NAC appeared poorly stable within liposomes. As DiNAC was quantified at concentrations which were twice as high as NAC in the perilymph, it was hypothesized that DiNAC could be responsible for the adverse effects on hearing.
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Affiliation(s)
- Céline Jaudoin
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
| | - Fabienne Carré
- Inserm/Institut Pasteur, Institut de l'audition, Technologies et thérapie génique pour la surdité, 63 rue de Charenton, 75012 Paris, France.
| | - Maria Gehrke
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
| | - Audrey Sogaldi
- UMS IPSIT, SAMM, Faculté de Pharmacie, Université Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
| | - Vincent Steinmetz
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France.
| | - Nathalie Hue
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France.
| | - Catherine Cailleau
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
| | - Guillaume Tourrel
- Oticon Medical/Neurelec SAS, Research & Technology Department, 2720 chemin Saint-Bernard, Vallauris, France.
| | - Yann Nguyen
- Inserm/Institut Pasteur, Institut de l'audition, Technologies et thérapie génique pour la surdité, 63 rue de Charenton, 75012 Paris, France; Sorbonne Université, AP-HP, GHU Pitié-Salpêtrière, DMU ChIR, Service ORL, GRC Robotique et Innovation Chirurgicale, 47-83, boulevard de l'hôpital, 75013 Paris, France.
| | - Evelyne Ferrary
- Inserm/Institut Pasteur, Institut de l'audition, Technologies et thérapie génique pour la surdité, 63 rue de Charenton, 75012 Paris, France.
| | - Florence Agnely
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
| | - Amélie Bochot
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 5 rue J-B Clément, 92296 Châtenay-Malabry, France.
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11
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Harris AR, Carter P, Cowan R, Wallace GG. Impact of Protein Fouling on the Charge Injection Capacity, Impedance, and Effective Electrode Area of Platinum Electrodes for Bionic Devices. ChemElectroChem 2021. [DOI: 10.1002/celc.202001574] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Alexander R. Harris
- Aikenhead Centre for Medical Discovery ARC Centre of Excellence for Electromaterials Science Faculty of Medicine, Dentistry and Health Sciences University of Melbourne Melbourne Vic 3010 Australia
- The HEARing CRC University of Melbourne 550 Swanston St Melbourne 3010 Australia
| | - Paul Carter
- Cochlear Ltd Macquarie University 1 University Ave Sydney NSW 2109 Australia
| | - Robert Cowan
- The HEARing CRC University of Melbourne 550 Swanston St Melbourne 3010 Australia
- Department of Audiology & Speech Pathology University of Melbourne 550 Swanston St Melbourne 3010 Australia
| | - Gordon G. Wallace
- ARC Centre of Excellence for Electromaterials Science Intelligent Polymer Research Institute University of Wollongong Wollongong, NSW 2522 Australia
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12
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Szeto B, Aksit A, Valentini C, Yu M, Werth EG, Goeta S, Tang C, Brown LM, Olson ES, Kysar JW, Lalwani AK. Novel 3D-printed hollow microneedles facilitate safe, reliable, and informative sampling of perilymph from guinea pigs. Hear Res 2021; 400:108141. [PMID: 33307286 PMCID: PMC8656365 DOI: 10.1016/j.heares.2020.108141] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/22/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND Inner ear diagnostics is limited by the inability to atraumatically obtain samples of inner ear fluid. The round window membrane (RWM) is an attractive portal for accessing perilymph samples as it has been shown to heal within one week after the introduction of microperforations. A 1 µL volume of perilymph is adequate for proteome analysis, yet the total volume of perilymph within the scala tympani of the guinea pig is limited to less than 5 µL. This study investigates the safety and reliability of a novel hollow microneedle device to aspirate perilymph samples adequate for proteomic analysis. METHODS The guinea pig RWM was accessed via a postauricular surgical approach. 3D-printed hollow microneedles with an outer diameter of 100 µm and an inner diameter of 35 µm were used to perforate the RWM and aspirate 1 µL of perilymph. Two perilymph samples were analyzed by liquid chromatography-mass spectrometry-based quantitative proteomics as part of a preliminary study. Hearing was assessed before and after aspiration using compound action potential (CAP) and distortion product otoacoustic emissions (DPOAE). RWMs were harvested 72 h after aspiration and evaluated for healing using confocal microscopy. RESULTS There was no permanent damage to hearing at 72 h after perforation as assessed by CAP (n = 7) and DPOAE (n = 8), and all perforations healed completely within 72 h (n = 8). In the two samples of perilymph analyzed, 620 proteins were detected, including the inner ear protein cochlin, widely recognized as a perilymph marker. CONCLUSION Hollow microneedles can facilitate aspiration of perilymph across the RWM at a quality and volume adequate for proteomic analysis without causing permanent anatomic or physiologic dysfunction. Microneedles can mediate safe and effective intracochlear sampling and show great promise for inner ear diagnostics.
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Affiliation(s)
- Betsy Szeto
- Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States
| | - Aykut Aksit
- Department of Mechanical Engineering, Columbia University, New York, NY, United States
| | - Chris Valentini
- Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States
| | - Michelle Yu
- Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States
| | - Emily G Werth
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Shahar Goeta
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Chuanning Tang
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Lewis M Brown
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Elizabeth S Olson
- Department of Biomedical Engineering, Columbia University, New York, NY, United States; Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States
| | - Jeffrey W Kysar
- Department of Mechanical Engineering, Columbia University, New York, NY, United States; Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States
| | - Anil K Lalwani
- Department of Otolaryngology - Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, 180 Fort Washington Avenue, Harkness Pavilion, 8th Floor, New York, NY 10032, United States; Department of Mechanical Engineering, Columbia University, New York, NY, United States.
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Moudgalya SS, Cahill ND, Borkholder DA. Deep Volumetric Segmentation of Murine Cochlear Compartments from Micro-Computed Tomography Images. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:1970-1975. [PMID: 33018389 PMCID: PMC7698689 DOI: 10.1109/embc44109.2020.9176596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Local drug delivery to the inner ear via micropump implants has the potential to be much more effective than oral drug delivery for treating patients with sensorineural hearing loss and to protect hearing from ototoxic insult due to noise exposure or cancer treatments. Designing micropumps to deliver appropriate concentrations of drugs to the necessary cochlear compartments is of paramount importance; however, directly measuring local drug concentrations over time throughout the cochlea is not possible. Recent approaches for indirectly quantifying local drug concentrations in animal models capture a series of magnetic resonance (MR) or micro computed tomography (µCT) images before and after infusion of a contrast agent into the cochlea. These approaches require accurately segmenting important cochlear components (scala tympani (ST), scala media (SM) and scala vestibuli (SV)) in each scan and ensuring that they are registered longitudinally across scans. In this paper, we focus on segmenting cochlear compartments from µCT volumes using V-Net, a convolutional neural network (CNN) architecture for 3-D segmentation. We show that by modifying the V-Net architecture to decrease the numbers of encoder and decoder blocks and to use dilated convolutions enables extracting local estimates of drug concentration that are comparable to those extracted using atlas-based segmentation (3.37%, 4.81%, and 19.65% average relative error in ST, SM, and SV), but in a fraction of the time. We also test the feasibility of training our network on a larger MRI dataset, and then using transfer learning to perform segmentation on a smaller number of µCT volumes, which would enable this technique to be used in the future to characterize drug delivery in the cochlea of larger mammals.
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Gausterer JC, Saidov N, Ahmadi N, Zhu C, Wirth M, Reznicek G, Arnoldner C, Gabor F, Honeder C. Intratympanic application of poloxamer 407 hydrogels results in sustained N-acetylcysteine delivery to the inner ear. Eur J Pharm Biopharm 2020; 150:143-155. [DOI: 10.1016/j.ejpb.2020.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 01/20/2020] [Accepted: 03/04/2020] [Indexed: 01/06/2023]
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15
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Four-point impedance as a biomarker for bleeding during cochlear implantation. Sci Rep 2020; 10:2777. [PMID: 32066743 PMCID: PMC7026160 DOI: 10.1038/s41598-019-56253-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/07/2019] [Indexed: 12/24/2022] Open
Abstract
Cochlear implantation has successfully restored the perception of hearing for nearly 200 thousand profoundly deaf adults and children. More recently, implant candidature has expanded to include those with considerable natural hearing which, when preserved, provides an improved hearing experience in noisy environments. But more than half of these patients lose this natural hearing soon after implantation. To reduce this burden, biosensing technologies are emerging that provide feedback on the quality of surgery. Here we report clinical findings on a new intra-operative measurement of electrical impedance (4-point impedance) which, when elevated, is associated with high rates of post-operative hearing loss and vestibular dysfunction. In vivo and in vitro data presented suggest that elevated 4-point impedance is likely due to the presence of blood within the cochlea rather than its geometry. Four-point impedance is a new marker for the detection of cochlear injury causing bleeding, that may be incorporated into intraoperative monitoring protocols during CI surgery.
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Takeda T, Takeda S, Kakigi A. A possible mechanism of the formation of endolymphatic hydrops and its associated inner ear disorders. Auris Nasus Larynx 2019; 47:25-41. [PMID: 31623941 DOI: 10.1016/j.anl.2019.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 08/29/2019] [Accepted: 09/12/2019] [Indexed: 12/19/2022]
Abstract
The pathology of Meniere's disease (MD) is well established to be endolymphatic hydrops. However, the mechanism underlying deafness and vertigo of MD or idiopathic endolymphatic hydrops is still unknown. In order to evaluate the pathogenesis of deafness and vertigo in MD, it seems to be rational to investigate the interrelationship between hydrops and inner ear disorders using animals with experimentally-induced endolymphatic hydrops. In spite of intense efforts by many researchers, the mechanism of vertiginous attack has been unexplained, because animals with experimental hydrops usually did not show vertiginous attack. Recently, there are two reports to succeed to evoke vertiginous attack in animals with experimental hydrops. In the present paper were first surveyed past proposals about underlying mechanism of the development of hydrops and inner ear disorders associated with hydrops, and were discussed the pathogenetic mechanism of vertiginous attack in hydrops. In conclusion, abrupt development of hydrops was thought to play a pivotal role in the onset of vertiginous seizure.
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Affiliation(s)
- Taizo Takeda
- Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi, Japan
| | | | - Akinobu Kakigi
- Department of Otolaryngology-Head & Neck Surgery, Kobe University, Graduate School of Medicine, Hyogo, Japan.
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17
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Ren Y, Landegger LD, Stankovic KM. Gene Therapy for Human Sensorineural Hearing Loss. Front Cell Neurosci 2019; 13:323. [PMID: 31379508 PMCID: PMC6660246 DOI: 10.3389/fncel.2019.00323] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/01/2019] [Indexed: 12/22/2022] Open
Abstract
Hearing loss is the most common sensory impairment in humans and currently disables 466 million people across the world. Congenital deafness affects at least 1 in 500 newborns, and over 50% are hereditary in nature. To date, existing pharmacologic therapies for genetic and acquired etiologies of deafness are severely limited. With the advent of modern sequencing technologies, there is a vast compendium of growing genetic alterations that underlie human hearing loss, which can be targeted by therapeutics such as gene therapy. Recently, there has been tremendous progress in the development of gene therapy vectors to treat sensorineural hearing loss (SNHL) in animal models in vivo. Nevertheless, significant hurdles remain before such technologies can be translated toward clinical use. These include addressing the blood-labyrinth barrier, engineering more specific and effective delivery vehicles, improving surgical access, and validating novel targets. In this review, we both highlight recent progress and outline challenges associated with in vivo gene therapy for human SNHL.
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Affiliation(s)
- Yin Ren
- Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
- Eaton Peabody Laboratories, Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, United States
| | - Lukas D. Landegger
- Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
- Eaton Peabody Laboratories, Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, United States
- Department of Otolaryngology, Vienna General Hospital, Medical University of Vienna, Vienna, Austria
| | - Konstantina M. Stankovic
- Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
- Eaton Peabody Laboratories, Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, United States
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, United States
- Harvard Program in Therapeutic Science, Harvard University, Boston, MA, United States
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18
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Moudgalya SS, Wilson K, Zhu X, Budzevich MM, Walton JP, Cahill ND, Frisina RD, Borkholder DA. Cochlear pharmacokinetics - Micro-computed tomography and learning-prediction modeling for transport parameter determination. Hear Res 2019; 380:46-59. [PMID: 31181459 DOI: 10.1016/j.heares.2019.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/21/2019] [Accepted: 05/29/2019] [Indexed: 10/26/2022]
Abstract
Inner ear disorders such as sensorineural deafness and genetic diseases may one day be treated with local drug delivery to the inner ear. Current pharmacokinetic models have been based on invasive methods to measure drug concentrations, limiting them in spatial resolution, and restricting the research to larger rodents. We developed an intracochlear pharmacokinetic model based on an imaging, learning-prediction (LP) paradigm for learning transport parameters in the murine cochlea. This was achieved using noninvasive micro-computed tomography imaging of the cochlea during in vivo infusion of a contrast agent at the basal end of scala tympani through a cochleostomy. Each scan was registered in 3-D to a cochlear atlas to segment the cochlear regions with high accuracy, enabling concentrations to be extracted along the length of each scala. These spatio-temporal concentration profiles were used to learn a concentration dependent diffusion coefficient, and transport parameters between the major scalae and to clearance. The LP model results are comparable to the current state of the art model, and can simulate concentrations for cases involving different infusion molecules and different drug delivery protocols. Forward simulation results with pulsatile delivery suggest the pharmacokinetic model can be used to optimize drug delivery protocols to reduce total drug delivered and the potential for toxic side effects. While developed in the challenging murine cochlea, the processes are scalable to larger animals and different drug infusion paradigms.
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Affiliation(s)
- Sanketh S Moudgalya
- Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY, USA
| | - Kevin Wilson
- Department of Electrical and Microelectronic Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Xiaoxia Zhu
- Department of Medical Engineering, University of Southern Florida, Tampa, FL, USA; Global Center for Hearing and Speech Research, University of Southern Florida, Tampa, FL, USA
| | | | - Joseph P Walton
- Department of Medical Engineering, University of Southern Florida, Tampa, FL, USA; Global Center for Hearing and Speech Research, University of Southern Florida, Tampa, FL, USA; Department of Communication Sciences and Disorders, University of Southern Florida, Tampa, FL, USA
| | - Nathan D Cahill
- Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY, USA; School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY, USA
| | - Robert D Frisina
- Department of Medical Engineering, University of Southern Florida, Tampa, FL, USA; Global Center for Hearing and Speech Research, University of Southern Florida, Tampa, FL, USA
| | - David A Borkholder
- Department of Electrical and Microelectronic Engineering, Rochester Institute of Technology, Rochester, NY, USA; Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USA.
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Sadreev II, Burwood GWS, Flaherty SM, Kim J, Russell IJ, Abdullin TI, Lukashkin AN. Drug Diffusion Along an Intact Mammalian Cochlea. Front Cell Neurosci 2019; 13:161. [PMID: 31080407 PMCID: PMC6497751 DOI: 10.3389/fncel.2019.00161] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/08/2019] [Indexed: 12/29/2022] Open
Abstract
Intratympanic drug administration depends on the ability of drugs to pass through the round window membrane (RW) at the base of the cochlea and diffuse from this location to the apex. While the RW permeability for many different drugs can be promoted, passive diffusion along the narrowing spiral of the cochlea is limited. Earlier measurements of the distribution of marker ions, corticosteroids, and antibiotics demonstrated that the concentration of substances applied to the RW was two to three orders of magnitude higher in the base compared to the apex. The measurements, however, involved perforating the cochlear bony wall and, in some cases, sampling perilymph. These manipulations can change the flow rate of perilymph and lead to intake of perilymph through the cochlear aqueduct, thereby disguising concentration gradients of the delivered substances. In this study, the suppressive effect of salicylate on cochlear amplification via block of the outer hair cell (OHC) somatic motility was utilized to assess salicylate diffusion along an intact guinea pig cochlea in vivo. Salicylate solution was applied to the RW and threshold elevation of auditory nerve responses was measured at different times and frequencies after application. Resultant concentrations of salicylate along the cochlea were calculated by fitting the experimental data using a mathematical model of the diffusion and clearing of salicylate in a tube of variable diameter combined with a model describing salicylate action on cochlear amplification. Concentrations reach a steady-state at different times for different cochlear locations and it takes longer to reach the steady-state at more apical locations. Even at the steady-state, the predicted concentration at the apex is negligible. Model predictions for the geometry of the longer human cochlea show even higher differences in the steady-state concentrations of the drugs between cochlear base and apex. Our findings confirm conclusions that achieving therapeutic drug concentrations throughout the entire cochlear duct is hardly possible when the drugs are applied to the RW and are distributed via passive diffusion. Assisted methods of drug delivery are needed to reach a more uniform distribution of drugs along the cochlea.
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Affiliation(s)
- Ildar I Sadreev
- Department of Medicine, Faculty of Medicine, Imperial College, London, United Kingdom
| | - George W S Burwood
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Samuel M Flaherty
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Jongrae Kim
- School of Mechanical Engineering, Institute of Design, Robotics and Optimisation, Aerospace Systems Engineering, University of Leeds, Leeds, United Kingdom
| | - Ian J Russell
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Timur I Abdullin
- Department of Biochemistry, Biotechnology and Pharmacology, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Andrei N Lukashkin
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.,Centre for Regenerative Medicine and Devices, University of Brighton, Brighton, United Kingdom
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20
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Harris AR, Newbold C, Carter P, Cowan R, Wallace GG. Using Chronopotentiometry to Better Characterize the Charge Injection Mechanisms of Platinum Electrodes Used in Bionic Devices. Front Neurosci 2019; 13:380. [PMID: 31118879 PMCID: PMC6508053 DOI: 10.3389/fnins.2019.00380] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 04/02/2019] [Indexed: 11/13/2022] Open
Abstract
The safe charge injection capacity and charge density of neural stimulating electrodes is based on empirical evidence obtained from stimulating feline cortices. Stimulation induced tissue damage may be caused by electrochemical or biological mechanisms. Separating these mechanisms requires greater understanding of charge transfer at the electrode-tissue interface. Clinical devices typically use a biphasic waveform with controlled current. Therefore, the charge injection mechanism and charge injection capacity of platinum was assessed on a commercial potentiostat by chronopotentiometry (controlled current stimulation). Platinum is a non-ideal electrode, charge injection by chronopotentiometry can be passed via capacitive and Faradaic mechanisms. Electrodes were tested under a variety of conditions to assess the impact on charge injection capacity. The change in electrode potential (charge injection capacity) was affected by applied charge density, pulse length, pulse polarity, electrode size, polishing method, electrolyte composition, and oxygen concentration. The safe charge injection capacity and charge density could be increased by changing the electrode-solution composition and stimulation parameters. However, certain conditions (e.g., acid polished electrodes) allowed the electrode to exceed the water electrolysis potential despite the stimulation protocol being deemed safe according to the Shannon plot. Multiple current pulses led to a shift or ratcheting in electrode potential due to changes in the electrode-solution composition. An accurate measure of safe charge injection capacity and charge density of an implantable electrode can only be obtained from suitable conditions (an appropriately degassed electrolyte and clinically relevant electrode structure). Cyclic voltammetric measurement of charge storage capacity can be performed on implantable electrodes, but will not provide information on electrode stability to multiple chronopotentiometric pulses. In contrast, chronopotentiometry will provide details on electrode stability, but the minimum time resolution of typical commercial potentiostats (ms range) is greater than used in a clinical stimulator (μs range) so that extrapolation to short stimulation pulses is required. Finally, an impedance test is typically used to assess clinical electrode performance. The impedance test is also based on a biphasic chronopotentiometic waveform where the measured potential is used to calculate an impedance value. Here it is shown that the measured potential is a function of many parameters (solution composition, electrode area, and surface composition). Subsequently, impedance test results allow electrode comparison and to indicate electrode failure, but use of Ohm's law to calculate an impedance value is not valid.
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Affiliation(s)
- Alexander R. Harris
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW, Australia
- The HEARing CRC, University of Melbourne, Melbourne, VIC, Australia
| | - Carrie Newbold
- The HEARing CRC, University of Melbourne, Melbourne, VIC, Australia
- Department of Audiology and Speech Pathology, University of Melbourne, Melbourne, VIC, Australia
| | - Paul Carter
- Cochlear, Ltd., Macquarie University, Sydney, NSW, Australia
| | - Robert Cowan
- The HEARing CRC, University of Melbourne, Melbourne, VIC, Australia
- Department of Audiology and Speech Pathology, University of Melbourne, Melbourne, VIC, Australia
| | - Gordon G. Wallace
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW, Australia
- The HEARing CRC, University of Melbourne, Melbourne, VIC, Australia
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21
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Hirose K, Li SZ. The role of monocytes and macrophages in the dynamic permeability of the blood-perilymph barrier. Hear Res 2019; 374:49-57. [PMID: 30710792 DOI: 10.1016/j.heares.2019.01.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/27/2018] [Accepted: 01/11/2019] [Indexed: 12/20/2022]
Abstract
The blood-perilymph barrier serves a critical role by separating the components of blood from inner ear fluids, limiting traffic of cells, proteins and other solutes into the labyrinth, and allowing gas (O2-CO2) exchange. Inflammation produces changes in the blood-perilymph barrier resulting in increased vascular permeability. It is commonly thought that compromise of the blood-inner ear barrier would lead to hearing impairment through loss of the endocochlear potential (EP). In fact, the effect of increasing cochlear vascular permeability on hearing function and EP is poorly understood. We used a novel method to measure the integrity of the blood-perilymph barrier and demonstrated the effects of barrier compromise on ABR threshold and EP. We also investigated the contribution of CX3CR1 cochlear macrophages and CCR2 inflammatory monocytes to barrier function after systemic exposure to lipopolysaccharide (LPS). We found that systemic LPS induced a profound change in vascular permeability, which correlated with minimal change in ABR threshold and EP. Macrophage depletion using CX3CR1-DTR mice did not alter the baseline permeability of cochlear vessels and resulted in preservation of barrier function in LPS-treated animals. We conclude that cochlear macrophages are not required to maintain the barrier in normal mice and activated macrophages are a critical factor in breakdown of the barrier after LPS. CCR2 null mice demonstrated that LPS induction of barrier leakiness occurs in the absence of CCR2 expression. Thus, enhanced aminoglycoside ototoxicity after LPS can be linked to the expression of CCR2 in inflammatory monocytes, and not to preservation of the blood-perilymph barrier in CCR2 knockout mice.
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Affiliation(s)
- Keiko Hirose
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, USA.
| | - Song-Zhe Li
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, USA
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22
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Marques P, Duan M, Perez-Fernandez N, Spratley J. Gentamicin delivery to the inner ear: Does endolymphatic hydrops matter? PLoS One 2018; 13:e0207467. [PMID: 30440019 PMCID: PMC6237362 DOI: 10.1371/journal.pone.0207467] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/31/2018] [Indexed: 12/13/2022] Open
Abstract
Introduction Middle ear application of gentamicin is a common medical treatment for uncontrolled Ménière’s disease. The objective of the study was to evaluate the impact of endolymphatic hydrops on inner ear delivery. Methods Perilymph gentamicin concentrations and correlation with endolymphatic hydrops in an animal model were assessed. A group of 24 guinea pigs was submitted to surgical obstruction of the endolymphatic sac and duct of the right ear. Gentamicin was applied either to the right ear’s round window niche or through a transtympanic injection. Perilymph specimens were collected at different times. Histologic morphometry was used to evaluate both turn-specific and overall hydrops degree. Results In animals with endolymphatic hydrops, lower concentrations of gentamicin were observed after 20 or 120 minutes of exposure and in both types of administration, when compared to controls. This difference reached statistical significance in the round window niche application group (Mann-Whitney, p = 0,007). A negative correlation between perilymphatic gentamicin concentration and hydrops degree could be observed in both groups, after 120 minutes of exposure (Spearman correlation, round window niche p<0,001; TT p = 0,005). Conclusions The study indicates that the endolymphatic hydrops degree has a negative interference on the delivery of gentamicin into the inner ear following middle ear application.
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Affiliation(s)
- Pedro Marques
- Department of Otorhinolaryngology, S.João Hospital Centre, Porto, Portugal
- Unit of Otorhinolaryngology, Department of Surgery and Physiology, University of Porto Medical School, Porto, Portugal
- * E-mail:
| | - Maoli Duan
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Department of Otolaryngology, Head and Neck Surgery, Karolinska Universisty Hospital, Karolinska Institutet, Stockholm, Sweden
| | | | - Jorge Spratley
- Department of Otorhinolaryngology, S.João Hospital Centre, Porto, Portugal
- Unit of Otorhinolaryngology, Department of Surgery and Physiology, University of Porto Medical School, Porto, Portugal
- Center for Health Technology and Services Research (CINTESIS), University of Porto Medical School, Porto, Portugal
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Wang Y, Han L, Diao T, Jing Y, Wang L, Zheng H, Ma X, Qi J, Yu L. A comparison of systemic and local dexamethasone administration: From perilymph/cochlea concentration to cochlear distribution. Hear Res 2018; 370:1-10. [PMID: 30223171 DOI: 10.1016/j.heares.2018.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/03/2018] [Accepted: 09/05/2018] [Indexed: 11/18/2022]
Abstract
Different types of inner ear diseases can damage different cochlear subsites by different mechanisms. Steroids administered by different methods are commonly used for treating inner ear diseases. There is reason to believe that dexamethasone (Dex) may reach cochlear subsite targets via different pathways after administration by different methods: Intratympanic (IT), postaural (PA), and intraperitoneal (IP). The purpose of this study was to explore the cochlear concentration and distribution of Dex after administration by different methods. High-performance liquid chromatography-mass spectrometry and immunofluorescence technology were employed to measure and compare the Dex concentration in the perilymph and cochlear tissue and the cochlear distribution of Dex. IT administration resulted in higher Dex concentrations in the perilymph and cochlear tissues than those with the other administration methods. Intratympanic and postaural administration could result in higher Dex concentrations in the organ of Corti than systemic administration, but systemic administration could result in higher Dex concentrations in the stria vascularis than the other administration methods. A decreasing basal-apical gradient of Dex uptake was present in the cochlea after IT but not IP or PA administration. These results indicate that different administration methods result in different Dex distributions, which can be attributed to features of the cochlear vascular system and intracochlear diffusion. Our results provide clinicians with an experimental basis for the use of different steroid injection routes to optimize the effects on inner ear diseases with different target organs.
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Affiliation(s)
- Yixu Wang
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Lin Han
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Tongxiang Diao
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Yuanyuan Jing
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Lin Wang
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Hongwei Zheng
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Xin Ma
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Jingcui Qi
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China
| | - Lisheng Yu
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, PR China.
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Creber NJ, Eastwood HT, Hampson AJ, Tan J, O'Leary SJ. Adjuvant agents enhance round window membrane permeability to dexamethasone and modulate basal to apical cochlear gradients. Eur J Pharm Sci 2018; 126:69-81. [PMID: 30107228 DOI: 10.1016/j.ejps.2018.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/22/2018] [Accepted: 08/09/2018] [Indexed: 01/09/2023]
Abstract
Glucocorticoids have direct anti-inflammatory, anti-oxidant and anti-apoptotic effects on cochlear hair cells. Cochlear glucocorticoid therapy has gained particular attention for its ability to enhance the protection of residual hearing following hearing preservation cochlear implantation. Local drug delivery methods achieve high drug concentrations within the inner ear fluids but are reliant upon diffusion across the round window membrane. Diffusion has been shown to demonstrate large individual variability. This study explores the role of "adjuvant agents", which when administered with glucocorticoids, enhance inner ear absorption and distribution. Guinea pig cochleae were administered either dexamethasone alone or in combination with hyaluronic acid, histamine, or combination histamine and hyaluronic acid, targeted at the round window membrane. Control subjects received saline. Perilymph was sampled from the cochlear apex, and basal to apical dexamethasone concentrations recorded with mass spectroscopy. Cochleae were harvested, and immunohistochemistry employed to explore dexamethasone tissue penetration and distribution. Basal to apical gradients were observed along the scala tympani, with higher dexamethasone concentrations observed at the cochlear base. Gradients were more pronounced and uniform when administered on a hyaluronic acid sponge, while histamine increased absolute concentrations reaching the inner ear. Tissue penetration correlated with perilymph concentration. Our results demonstrate that adjuvant agents can be employed to enhance dexamethasone absorption and distribution in the inner ear, thus proposing therapeutic strategies that may enhance steroid facilitated hearing protection.
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Affiliation(s)
- Nathan J Creber
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia.
| | - Hayden T Eastwood
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Justin Tan
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Stephen J O'Leary
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia; Royal Victorian Eye and Ear Hospital, East Melbourne 3002, Australia
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Harris AR, Newbold C, Carter P, Cowan R, Wallace GG. Measuring the effective area and charge density of platinum electrodes for bionic devices. J Neural Eng 2018; 15:046015. [DOI: 10.1088/1741-2552/aaba8b] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Salt AN, Hirose K. Communication pathways to and from the inner ear and their contributions to drug delivery. Hear Res 2018; 362:25-37. [PMID: 29277248 PMCID: PMC5911243 DOI: 10.1016/j.heares.2017.12.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/08/2017] [Accepted: 12/05/2017] [Indexed: 01/04/2023]
Abstract
The environment of the inner ear is highly regulated in a manner that some solutes are permitted to enter while others are excluded or transported out. Drug therapies targeting the sensory and supporting cells of the auditory and vestibular systems require the agent to gain entry to the fluid spaces of the inner ear, perilymph or endolymph, which surround the sensory organs. Access to the inner ear fluids from the vasculature is limited by the blood-labyrinth barriers, which include the blood-perilymph and blood-strial barriers. Intratympanic applications provide an alternative approach in which drugs are applied locally. Drug from the applied solution enters perilymph through the round window membrane, through the stapes, and under some circumstances, through thin bone in the otic capsule. The amount of drug applied to the middle ear is always substantially more than the amount entering perilymph. As a result, significant amounts of the applied drug can pass to the digestive system, to the vasculature, and to the brain. Drugs in perilymph pass to the vasculature and to cerebrospinal fluid via the cochlear aqueduct. Conversely, drugs applied to cerebrospinal fluid, including those given intrathecally, can enter perilymph through the cochlear aqueduct. Other possible routes in or out of the ear include passage by neuronal pathways, passage via endolymph and the endolymphatic sac, and possibly via lymphatic pathways. A better understanding of the pathways for drug movements in and out of the ear will enable better intervention strategies.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO, USA.
| | - Keiko Hirose
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO, USA
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Schroeder RJ, Audlin J, Luo J, Nicholas BD. Pharmacokinetics of sodium thiosulfate in Guinea pig perilymph following middle ear application. J Otol 2018; 13:54-58. [PMID: 30559765 PMCID: PMC6291635 DOI: 10.1016/j.joto.2017.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/29/2017] [Accepted: 12/05/2017] [Indexed: 11/17/2022] Open
Abstract
Hypothesis To determine the pharmacokinetics of sodium thiosulfate in the inner ear perilymph following middle ear application in Guinea pigs. Background Cisplatin chemotherapy is often associated with a dose-dependent high frequency sensorineural hearing loss. Sodium thiosulfate has been shown to reduce cisplatin-induced ototoxicity when given intravenously, but this may limit the tumoricidal effects of the chemotherapy. Recent animal studies looking at middle ear application of sodium thiosulfate have shown prevention of outer hair cell and hearing loss, but the perilymph pharmacokinetics have not yet been established. Methods Twenty Guinea pig ears were split into two groups and administered sodium thiosulfate to the middle ear at either a concentration of 250 mg/mL or 50 mg/mL for 30 min. Perilymph samples were then obtained serially through the round window over 6 h. Sodium thiosulfate concentrations were obtained using high-pressure liquid chromatography. Results The 250 mg/mL group had a maximum perilymph concentration of 7.27 mg/mL (±0.83) that decreased to 0.94 mg/mL (±0.03) over 6 h. The 50 mg/mL group had an initial concentration of 1.63 mg/mL (±0.17) and was undetectable after 1 h. The half-life of sodium thiosulfate within perilymph was 0.74 h. Conclusions and Relevance: The results of this study show that sodium thiosulfate is capable of diffusing through round window and into the inner ear perilymph. Peak levels decline over several hours after exposure. This has a potential application as a localized therapy in the prevention of cisplatin induced ototoxicity.
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Dai J, Long W, Liang Z, Wen L, Yang F, Chen G. A novel vehicle for local protein delivery to the inner ear: injectable and biodegradable thermosensitive hydrogel loaded with PLGA nanoparticles. Drug Dev Ind Pharm 2017; 44:89-98. [PMID: 28851247 DOI: 10.1080/03639045.2017.1373803] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Delivery of biomacromolecular drugs into the inner ear is challenging, mainly because of their inherent instability as well as physiological and anatomical barriers. Therefore, protein-friendly, hydrogel-based delivery systems following local administration are being developed for inner ear therapy. Herein, biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing interferon α-2 b (IFN α-2 b) were loaded in chitosan/glycerophosphate (CS/GP)-based thermosensitive hydrogel for IFN delivery by intratympanic injection. The injectable hydrogel possessed a physiological pH and formed semi-solid gel at 37 °C, with good swelling and deswelling properties. The CS/GP hydrogel could slowly degrade as visualized by scanning electron microscopy (SEM). The presence of NPs in CS/GP gel largely influenced in vitro drug release. In the guinea pig cochlea, a 1.5- to 3-fold increase in the drug exposure time of NPs-CS/GP was found than those of the solution, NPs and IFN-loaded hydrogel. Most importantly, a prolonged residence time was attained without obvious histological changes in the inner ear. This biodegradable, injectable, and thermosensitive NPs-CS/GP system may allow longer delivery of protein drugs to the inner ear, thus may be a potential novel vehicle for inner ear therapy.
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Affiliation(s)
- Juan Dai
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China.,b Guangdong Provincial Key Laboratory of Advanced Drug Delivery , Guangdong Pharmaceutical University , Guangzhou , China
| | - Wei Long
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China.,b Guangdong Provincial Key Laboratory of Advanced Drug Delivery , Guangdong Pharmaceutical University , Guangzhou , China
| | - Zhongping Liang
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China.,b Guangdong Provincial Key Laboratory of Advanced Drug Delivery , Guangdong Pharmaceutical University , Guangzhou , China
| | - Lu Wen
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China
| | - Fan Yang
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China.,b Guangdong Provincial Key Laboratory of Advanced Drug Delivery , Guangdong Pharmaceutical University , Guangzhou , China
| | - Gang Chen
- a School of Pharmacy , Guangdong Pharmaceutical University , Guangzhou , China.,b Guangdong Provincial Key Laboratory of Advanced Drug Delivery , Guangdong Pharmaceutical University , Guangzhou , China
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Schmitt HA, Pich A, Schröder A, Scheper V, Lilli G, Reuter G, Lenarz T. Proteome Analysis of Human Perilymph Using an Intraoperative Sampling Method. J Proteome Res 2017; 16:1911-1923. [DOI: 10.1021/acs.jproteome.6b00986] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Heike A. Schmitt
- Department
of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence of the German Research Foundation (DFG; “Deutsche
Forschungsgemeinschaft”) “Hearing4all”, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Andreas Pich
- Core
Facility Proteomics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Anke Schröder
- Core
Facility Proteomics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Verena Scheper
- Department
of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence of the German Research Foundation (DFG; “Deutsche
Forschungsgemeinschaft”) “Hearing4all”, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Giorgio Lilli
- Department
of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence of the German Research Foundation (DFG; “Deutsche
Forschungsgemeinschaft”) “Hearing4all”, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Günter Reuter
- Department
of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence of the German Research Foundation (DFG; “Deutsche
Forschungsgemeinschaft”) “Hearing4all”, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Thomas Lenarz
- Department
of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Cluster
of Excellence of the German Research Foundation (DFG; “Deutsche
Forschungsgemeinschaft”) “Hearing4all”, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Internal Jugular Vein Compression: A Novel Approach to Mitigate Blast Induced Hearing Injury. Otol Neurotol 2017; 38:591-598. [DOI: 10.1097/mao.0000000000001332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wangemann P, Marcus DC. Ion and Fluid Homeostasis in the Cochlea. UNDERSTANDING THE COCHLEA 2017. [DOI: 10.1007/978-3-319-52073-5_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Hyaluronic acid liposomal gel sustains delivery of a corticoid to the inner ear. J Control Release 2016; 226:248-57. [DOI: 10.1016/j.jconrel.2016.02.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 02/03/2016] [Accepted: 02/05/2016] [Indexed: 12/15/2022]
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Micro-CT analysis of the anatomical characteristics of the stapedial annular ligament. Anat Sci Int 2016; 92:262-266. [DOI: 10.1007/s12565-016-0331-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 02/01/2016] [Indexed: 12/26/2022]
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Liu Y, Jolly C, Braun S, Stark T, Scherer E, Plontke SK, Kiefer J. In vitro and in vivo pharmacokinetic study of a dexamethasone-releasing silicone for cochlear implants. Eur Arch Otorhinolaryngol 2015; 273:1745-53. [PMID: 26319276 DOI: 10.1007/s00405-015-3760-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 08/21/2015] [Indexed: 01/12/2023]
Abstract
Cochlear implants have been widely used for patients with profound hearing loss and partial deafness. Residual low-frequency hearing, however, may deteriorate due to insertion trauma and tissue response around the electrode array. The present study investigated in vitro and in vivo release of dexamethasone from silicone used for cochlear implant electrode carriers. The in vitro experiment involved an apparatus simulating the inner ear fluid environment in humans. Release from two sizes of silicone films (200 µm × 1 mm × 10 mm and 500 µm × 1 mm × 10 mm), each loaded with 2 % dexamethasone, and was measured for 24 weeks. In the in vivo experiment, silicone rods loaded with 2 or 10 % dexamethasone, respectively, were implanted into the scala tympani of guinea pigs. Perilymph concentrations were measured during the first week after implantation. The results showed that dexamethasone was released from the silicone in a sustained manner. After a burst release, perilymph concentration was similar for silicone incorporated with 2 and 10 % dexamethasone, respectively. The similar pharmacokinetic profile was found in the in vitro experiment. The period of sustained drug delivery was maintained for 20 weeks in vitro and for 1 week in vivo. The results of the present study suggest that drugs like dexamethasone are released in a controlled manner from silicon electrode carriers of cochlear implants. Further studies will identify optimal release profiles for the use with cochlear implants to improve their safety and long-term performance.
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Affiliation(s)
- Ya Liu
- Department of Otolaryngology, Head and Neck Surgery, Beijing Naval General Hospital, Beijing, 100048, People's Republic of China
| | - Claude Jolly
- Electrode Research Section, MED-EL Medical Electronics, Innsbruck, Austria
| | | | - Thomas Stark
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Elias Scherer
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Jan Kiefer
- HNO-Zentrum, Neupfarrplatz 12/II, 93047, Regensburg, Germany.
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Recent advances in local drug delivery to the inner ear. Int J Pharm 2015; 494:83-101. [PMID: 26260230 DOI: 10.1016/j.ijpharm.2015.08.015] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 07/31/2015] [Accepted: 08/05/2015] [Indexed: 12/14/2022]
Abstract
Inner ear diseases are not adequately treated by systemic drug administration mainly because of the blood-perilymph barrier that reduces exchanges between plasma and inner ear fluids. Local drug delivery methods including intratympanic and intracochlear administrations are currently developed to treat inner ear disorders more efficiently. Intratympanic administration is minimally invasive but relies on diffusion through middle ear barriers for drug entry into the cochlea, whereas intracochlear administration offers direct access to the colchlea but is rather invasive. A wide range of drug delivery systems or devices were evaluated in research and clinic over the last decade for inner ear applications. In this review, different strategies including medical devices, hydrogels and nanoparticulate systems for intratympanic administration, and cochlear implant coating or advanced medical devices for intracoclear administration were explored with special attention to in vivo studies. This review highlights the promising systems for future clinical applications as well as the current hurdles that remain to be overcome for efficient inner ear therapy.
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Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid. J Assoc Res Otolaryngol 2015; 16:357-71. [PMID: 25801074 DOI: 10.1007/s10162-015-0512-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/13/2015] [Indexed: 02/07/2023] Open
Abstract
Understanding how drugs are distributed in perilymph following local applications is important as local drug therapies are increasingly used to treat disorders of the inner ear. The potential contribution of cerebrospinal fluid (CSF) entry to perilymph homeostasis has been controversial for over half a century, largely due to artifactual contamination of collected perilymph samples with CSF. Measures of perilymph flow and of drug distribution following round window niche applications have both suggested a slow, apically directed flow occurs along scala tympani (ST) in the normal, sealed cochlea. In the present study, we have used fluorescein isothiocyanate-dextran as a marker to study perilymph kinetics in guinea pigs. Dextran is lost from perilymph more slowly than other substances so far quantified. Dextran solutions were injected from pipettes sealed into the lateral semicircular canal (SCC), the cochlear apex, or the basal turn of ST. After varying delays, sequential perilymph samples were taken from the cochlear apex or lateral SCC, allowing dextran distribution along the perilymphatic spaces to be quantified. Variability was low and findings were consistent with the injection procedure driving volume flow towards the cochlear aqueduct, and with volume flow during perilymph sampling driven by CSF entry at the aqueduct. The decline of dextran with time in the period between injection and sampling was consistent with both a slow volume influx of CSF (~30 nL/min) entering the basal turn of ST at the cochlear aqueduct and a CSF-perilymph exchange driven by pressure-driven fluid oscillation across the cochlear aqueduct. Sample data also allowed contributions of other processes, such as communications with adjacent compartments, to be quantified. The study demonstrates that drug kinetics in the basal turn of ST is complex and is influenced by a considerable number of interacting processes.
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Adjudin protects rodent cochlear hair cells against gentamicin ototoxicity via the SIRT3-ROS pathway. Sci Rep 2015; 5:8181. [PMID: 25640330 PMCID: PMC4313083 DOI: 10.1038/srep08181] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 12/18/2014] [Indexed: 12/15/2022] Open
Abstract
Hearing loss resulting from hair cell degeneration is a common disease that affects millions of people worldwide. Strategies to overcome the apparent irreversible hair cell loss in mammals become paramount for hearing protection. Here we reported that, by using a well-established gentamicin-induced hair cell loss model in vitro, adjudin, a multi-functional small molecule drug, protected cochlear hair cells from gentamicin damage. Immunohistochemistry, Western blotting and quantitative RT-PCR analyses revealed that adjudin exerted its otoprotective effects by up-regulating the level of Sirt3, a member of Sirtuin family protein located in mitochondria, which regulates reactive oxygen species (ROS) production in cochlear cells and inhibits the production of ROS and apoptotic cells induced by gentamicin. Sirt3 silencing experiments confirmed that Sirt3-ROS signaling axis mediated hair cell protection against gentamicin by adjudin, at least in part. Furthermore, adjudin's otoprotection effects were also observed in an in vivo gentamicin-injured animal model. Taken together, these findings identify adjudin as a novel otoprotective small molecule via elevating Sirt3 levels and Sirt3 may be of therapeutic value in hair cell protection from ototoxic insults.
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Abstract
Safety pharmacology satisfies a key requirement in the process of drug development. Safety pharmacology studies are required to assess the impact of a new chemical entity (NCE) or biotechnology-derived product for human use on vital systems, such as those subserving auditory function. Safety pharmacology studies accordingly are defined as those studies that investigate the potential undesirable effects of a substance on auditory functions in relation to exposure in and above the therapeutic range. Auditory safety studies should be designed with the primary objective of determining how administration of a compound influences normal hearing. If an effect on hearing is identified, then it is necessary to determine through histopathology the underlying mechanism for the observed hearing loss. Since the auditory system contains a heterogeneous mixture of structural and cellular components that are organized in a very complex and integrated manner, it is necessary to clearly identify the underlying primary mechanism or target of the new chemical entity that produced the hearing loss. This chapter will highlight major components of auditory function with regard to potential opportunities for drug interaction. Aspects of designing ototoxicity studies will be discussed with an emphasis on standards deemed necessary by the US Food and Drug Administration. Additionally, classes of ototoxic compounds and their proposed mechanisms of action are described in depth.
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Isosorbide concentration in perilymph of the Guinea pig after oral administration versus that after round window perfusion. Clin Exp Otorhinolaryngol 2014; 7:281-5. [PMID: 25436047 PMCID: PMC4240485 DOI: 10.3342/ceo.2014.7.4.281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/24/2014] [Accepted: 04/21/2014] [Indexed: 11/08/2022] Open
Abstract
Objectives The aims of this study were to investigate the feasibility of isosorbide delivery into perilymph through the round window membrane (RWM), and to compare the intracochlear isosorbide concentration in perilymph after oral administration (PO) versus that after round window perfusion (RWP). Methods Sixteen male guinea pigs (32 ears) were used. Isosorbide, an osmotic diuretic, was administered via RWP or PO. First, to investigate the optimal perfusion time, perilymph sampling of scala tympani from the RWM was performed after RWP for 15, 30, or 60 minutes. Second, to compare the drug concentration after RWP versus that after PO, perilymph was aspirated at 3 and 6 hours after administration. Intracochlear concentration of isosorbide was analyzed by high-performance liquid chromatography coupled to refractive index detection. Results Isosorbide passed through the RWM into perilymph after RWP. After RWP for 15, 30, and 60 minutes, mean isosorbide concentrations in perilymph were 116.27±44.65, 245.48±112.84, and 279.78±186.32 mM, respectively. The intracochlear concentration after RWP for 30 minutes was higher than that after RWP for 15 minutes (P=0.043). At 3 and 6 hours after PO, isosorbide concentrations in perilymph were 28.88±4.69 and 12.67±2.28 mM, respectively. In contrast, the corresponding concentrations after RWP were 117.91±17.70 and 75.03±14.82 mM at 3 and 6 hours, respectively. Isosorbide concentrations in perilymph following RWP were significantly higher than those following PO at both 3 and 6 hours (P=0.025 and P=0.034, respectively). Conclusion Isosorbide can rapidly pass through the RWM after RWP in guinea pigs, and 30 minutes of perfusion is considered to be appropriate. In addition, over a 6-hour period, RWP can deliver higher concentrations of isosorbide into perilymph than those achieved with PO.
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Systemic lipopolysaccharide compromises the blood-labyrinth barrier and increases entry of serum fluorescein into the perilymph. J Assoc Res Otolaryngol 2014; 15:707-19. [PMID: 24952083 DOI: 10.1007/s10162-014-0476-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 06/03/2014] [Indexed: 12/20/2022] Open
Abstract
The blood vessels that supply the inner ear form a barrier between the blood and the inner ear fluids to control the exchange of solutes, protein, and water. This barrier, called the blood-labyrinth barrier (BLB) is analogous to the blood-brain barrier (BBB), which plays a critical role in limiting the entry of inflammatory and infectious agents into the central nervous system. We have developed an in vivo method to assess the functional integrity of the BLB by injecting sodium fluorescein into the systemic circulation of mice and measuring the amount of fluorescein that enters perilymph in live animals. In these experiments, perilymph was collected from control and experimental mice in sequential samples taken from the posterior semicircular canal approximately 30 min after systemic fluorescein administration. Perilymph fluorescein concentrations in control mice were compared with perilymph fluorescein concentrations after lipopolysaccharide (LPS) treatment (1 mg/kg IP daily for 2 days). The concentration of perilymphatic fluorescein, normalized to serum fluorescein, was significantly higher in LPS-treated mice compared to controls. In order to assess the contributions of perilymph and endolymph in our inner ear fluid samples, sodium ion concentration of the inner ear fluid was measured using ion-selective electrodes. The sampled fluid from the posterior semicircular canal demonstrated an average sodium concentration of 145 mM, consistent with perilymph. These experiments establish a novel technique to assess the functional integrity of the BLB using quantitative methods and to provide a comparison of the BLB to the BBB.
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Ráth G, Katona G, Bakó P, Török L, Révész P, Tóth E, Gerlinger I. Application of ionomer cement onto the stapedial footplate: Impact on the perilymphatic aluminum level. Laryngoscope 2014; 124:541-4. [DOI: 10.1002/lary.24289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/12/2013] [Accepted: 06/12/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Gábor Ráth
- Department of Pediatric Otorhinolaryngology; Pécs University, Pécs; Budapest Hungary
| | - Gábor Katona
- Department of Pediatric Otorhinolaryngology and Bronchology; Heim Pál Hospital; Budapest Hungary
| | - Péter Bakó
- Department of Otorhinolaryngology & Head and Neck Surgery; Pécs University, Pécs; Budapest Hungary
| | - László Török
- Department of Otorhinolaryngology & Head and Neck Surgery; Pécs University, Pécs; Budapest Hungary
| | - Péter Révész
- Department of Otorhinolaryngology & Head and Neck Surgery; Pécs University, Pécs; Budapest Hungary
| | - Edit Tóth
- Klebelsberg Institution Maintenance Center; Hungary; Budapest Hungary
| | - Imre Gerlinger
- Department of Otorhinolaryngology & Head and Neck Surgery; Pécs University, Pécs; Budapest Hungary
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Astolfi L, Guaran V, Marchetti N, Olivetto E, Simoni E, Cavazzini A, Jolly C, Martini A. Cochlear implants and drug delivery:In vitroevaluation of dexamethasone release. J Biomed Mater Res B Appl Biomater 2013; 102:267-73. [DOI: 10.1002/jbm.b.33004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/30/2013] [Accepted: 07/01/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Laura Astolfi
- Department of Neuroscience, Bioacoustics Research Laboratory; University of Padua; 35129 Padua Italy
| | - Valeria Guaran
- Department of Neuroscience, Bioacoustics Research Laboratory; University of Padua; 35129 Padua Italy
| | - Nicola Marchetti
- Department of Chemistry and Pharmaceutical Sciences; University of Ferrara; 44121 Ferrara Italy
| | - Elena Olivetto
- Department of Neuroscience, Bioacoustics Research Laboratory; University of Padua; 35129 Padua Italy
| | - Edi Simoni
- Department of Neuroscience, Bioacoustics Research Laboratory; University of Padua; 35129 Padua Italy
| | - Alberto Cavazzini
- Department of Chemistry and Pharmaceutical Sciences; University of Ferrara; 44121 Ferrara Italy
| | - Claude Jolly
- MED-EL Hearing Implants; Innsbruck A6020 Austria
| | - Alessandro Martini
- Department of Neurosciences, ENT and Otosurgery Unit; University of Padua; 35129 Padua Italy
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Hellberg V, Wallin I, Ehrsson H, Laurell G. Cochlear pharmacokinetics of cisplatin: an in vivo study in the guinea pig. Laryngoscope 2013; 123:3172-7. [PMID: 23754209 DOI: 10.1002/lary.24235] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 05/14/2013] [Accepted: 05/14/2013] [Indexed: 12/20/2022]
Abstract
OBJECTIVES/HYPOTHESIS Cisplatin produces toxic lesions to outer hair cells (OHCs) in the cochlear base but not in the apex. The objective of this study was to compare the pharmacokinetic profile of cisplatin in scala tympani (ST) perilymph in the cochlear base and apex, respectively. STUDY DESIGN In vivo animal study. METHODS Forty-seven guinea pigs were given an intravenous bolus injection of an ototoxic dose of cisplatin. Ten to 240 minutes after cisplatin was given, blood, cerebrospinal fluid (CSF), and ST perilymph were aspirated within the same target time. ST perilymph was aspirated from the basal turn and from the apex of the cochlea by two different sampling techniques. Liquid chromatography with postcolumn derivatization was used for quantitative determination of the parent drug. RESULTS Ten minutes after administration, the concentration of cisplatin in ST perilymph was 4-fold higher in the basal turn of the cochlea than in the apex. At 30 minutes, the drug concentrations did not differ. At 60 minutes, the level of cisplatin in ST perilymph and blood UF was equivalent. The perilymph-blood ratio increased thereafter with time. CONCLUSION The pharmacokinetic findings of an early high concentration of cisplatin in the base of the cochlea and delayed elimination of cisplatin from ST perilymph compared to blood might correlate to the cisplatin-induced loss of OHCs in the base of the cochlea.
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Affiliation(s)
- Victoria Hellberg
- Department of Clinical Science, Intervention, and Technology, Karolinska Institutet, Stockholm, Sweden
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Gentamicin administration on the stapes footplate causes greater hearing loss and vestibulotoxicity than round window administration in guinea pigs. Hear Res 2013; 304:159-66. [PMID: 23899413 DOI: 10.1016/j.heares.2013.07.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 07/11/2013] [Accepted: 07/18/2013] [Indexed: 11/21/2022]
Abstract
Clinically, gentamicin has been used extensively to treat the debilitating symptoms of Mèniére's disease and is well known for its vestibulotoxic properties. Until recently, it was widely accepted that the round window membrane (RWM) was the primary entry route into the inner ear following intratympanic drug administration. In the current study, gentamicin was delivered to either the RWM or the stapes footplate of guinea pigs (GPs) to assess the associated hearing loss and histopathology associated with each procedure. Vestibulotoxicity of the utricular macula, saccular macula, and crista ampullaris in the posterior semicircular canal were assessed quantitatively with density counts of hair cells, supporting cells, and stereocilia in histological sections. Cochleotoxicity was assessed quantitatively by changes in threshold of auditory brainstem responses (ABR), along with hair cell and spiral ganglion cell counts in the basal and second turns of the cochlea. Animals receiving gentamicin applied to the stapes footplate exhibited markedly higher levels of hearing loss between 8 and 32 kHz, a greater reduction of outer hair cells in the basal turn of the cochlea and fewer normal type I cells in the utricle in the vestibule than those receiving gentamicin on the RWM or saline controls. This suggests that gentamicin more readily enters the ear when applied to the stapes footplate compared with RWM application. These data provide a potential explanation for why gentamicin preferentially ablates vestibular function while preserving hearing following transtympanic administration in humans.
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Dexamethasone levels and base-to-apex concentration gradients in the scala tympani perilymph after intracochlear delivery in the guinea pig. Otol Neurotol 2012; 33:660-5. [PMID: 22588238 DOI: 10.1097/mao.0b013e318254501b] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS To determine whether intracochlearly applied dexamethasone will lead to better control of drug levels, higher peak concentrations, and lower base-to-apex concentration gradients in the scala tympani (ST) of the guinea pig than after intratympanic (round window [RW]) application. BACKGROUND Local application of drugs to the RW results in substantial variation of intracochlear drug levels and significant base-to-apex concentration gradients in ST. METHODS Two microliters of dexamethasone-phosphate (10 mg/ml) were injected into ST either through the RW membrane, which was covered with 1% sodium hyaluronate gel or through a cochleostomy with a fluid tight seal of the micropipette. Perilymph was sequentially sampled from the apex at a single time point for each animal, at 20, 80, or 200 min after the injection ended. Results were mathematically interpreted by means of an established computer model and compared with previous experiments performed by our group with the same experimental techniques but using intratympanic applications. RESULTS Single intracochlear injections of 20 minutes resulted in approximately 10 times higher peak concentrations (on average) than 2 to 3 hours of intratympanic application to the RW niche. Intracochlear drug levels were less variable and could be measured for over 220 minutes. Concentration gradients along the scala tympani were less pronounced. The remaining variability in intracochlear drug levels was attributable to perilymph and drug leak from the injection site. CONCLUSION With significantly higher, less variable drug levels and smaller base-to-apex concentration gradients, intracochlear applications have advantages to intratympanic injections. For further development of this technique, it is of importance to control leaks of perilymph and drug from the injection site and to evaluate its clinical feasibility and associated risks.
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Perilymph pharmacokinetics of markers and dexamethasone applied and sampled at the lateral semi-circular canal. J Assoc Res Otolaryngol 2012; 13:771-83. [PMID: 22968908 DOI: 10.1007/s10162-012-0347-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/13/2012] [Indexed: 10/27/2022] Open
Abstract
Perilymph pharmacokinetics was investigated by a novel approach, in which solutions containing drug or marker were injected from a pipette sealed into the perilymphatic space of the lateral semi-circular canal (LSCC). The cochlear aqueduct provides the outlet for fluid flow so this procedure allows almost the entire perilymph to be exchanged. After wait times of up to 4 h the injection pipette was removed and multiple, sequential samples of perilymph were collected from the LSCC. Fluid efflux at this site results from cerebrospinal fluid (CSF) entry into the basal turn of scala tympani (ST) so the samples allow drug levels from different locations in the ear to be defined. This method allows the rate of elimination of substances from the inner ear to be determined more reliably than with other delivery methods in which drug may only be applied to part of the ear. Results were compared for the markers trimethylphenylammonium (TMPA) and fluorescein and for the drug dexamethasone (Dex). For each substance, the concentration in fluid samples showed a progressive decrease as the delay time between injection and sampling was increased. This is consistent with the elimination of substance from the ear with time. The decline with time was slowest for fluorescein, was fastest for Dex, with TMPA at an intermediate rate. Simulations of the experiments showed that elimination occurred more rapidly from scala tympani (ST) than from scala vestibuli (SV). Calculated elimination half-times from ST averaged 54.1, 24.5 and 22.5 min for fluorescein, TMPA and Dex respectively and from SV 1730, 229 and 111 min respectively. The elimination of Dex from ST occurred considerably faster than previously appreciated. These pharmacokinetic parameters provide an important foundation for understanding of drug treatments of the inner ear.
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Xia L, Yin S, Wang J. Inner ear gene transfection in neonatal mice using adeno-associated viral vector: a comparison of two approaches. PLoS One 2012; 7:e43218. [PMID: 22912830 PMCID: PMC3422324 DOI: 10.1371/journal.pone.0043218] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/18/2012] [Indexed: 01/06/2023] Open
Abstract
Local gene transfection is a promising technique for the prevention and/or correction of inner ear diseases, particularly those resulting from genetic defects. Adeno-associated virus (AAV) is an ideal viral vector for inner ear gene transfection because of its safety, stability, long-lasting expression, and its high tropism for many different cell types. Recently, a new generation of AAV vectors with a tyrosine mutation (mut-AAV) has demonstrated significant improvement in transfection efficiency. A method for inner ear gene transfection via the intact round window membrane (RWM) has been developed in our laboratory. This method has not been tested in neonatal mice, an important species for the study of inherited hearing loss. Following a preliminary study to optimize the experimental protocol in order to reduce mortality, the present study investigated inner ear gene transfection in mice at postnatal day 7. We compared transfection efficiency, the safety of the scala tympani injection via RWM puncture, and the trans-RWM diffusion following partial digestion with an enzyme technique. The results revealed that approximately 47% of inner hair cells (IHCs) and 17% of outer hair cells (OHCs) were transfected via the trans-RWM approach. Transfection efficiency via RWM puncture (58% and 19% for IHCs and OHCs, respectively) was slightly higher, but the difference was not significant.
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Affiliation(s)
- Li Xia
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
| | - Shankai Yin
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
- * E-mail: (SY); (JW)
| | - Jian Wang
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
- School of Human Communication Disorder, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (SY); (JW)
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Liu J, Yu P, Lin Y, Zhou N, Li T, Ma F, Mao L. In vivo electrochemical monitoring of the change of cochlear perilymph ascorbate during salicylate-induced tinnitus. Anal Chem 2012; 84:5433-8. [PMID: 22703231 DOI: 10.1021/ac301087v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
As one of the most important neurochemicals in biological systems, ascorbate plays vital roles in many physiological and pathological processes. In order to understand the roles of ascorbate in the pathological process of tinnitus, this study demonstrates an in vivo method for real time monitoring of the changes of ascorbate level in the cochlear perilymph of guinea pigs during the acute period of tinnitus induced by local microinfusion of salicylate with carbon fiber microelectrodes (CFMEs) modified with multiwalled carbon nanotubes (MWNTs). To accomplish in vivo electrochemical monitoring of ascorbate in the microenvironment of the cochlear perilymph, the MWNT-modified CFME is used as working electrode, a microsized Ag/AgCl is used as reference electrode, and Pt wire is used as counter electrode. Three electrodes are combined together around a capillary to form integrated capillary-electrodes. The integrated capillary-electrode is carefully implanted into the cochlear perilymph of guinea pigs and used both for externally microinfusing of salicylate into the cochlear perilymph and for real time monitoring of the change of ascorbate levels. The in vivo voltammetric method based on the integrated capillary-electrodes possesses a high selectivity and a good linearity for ascorbate determination in the cochlear perilymph of guinea pigs. With such a method, the basal level of cochlear perilymph ascorbate is determined to be 45.0 ± 5.1 μM (n = 6). The microinfusion of 10 mM salicylate (1 μL/min, 5 min) into the cochlear decreases the ascorbate level to 28 ± 10% of the basal level (n = 6) with a statistical significance (P < 0.05), implying that the decrease in ascorbate level in the cochlear may be associated with salicylate-induced tinnitus. This study essentially offers a new method for in vivo monitoring of the cochlear perilymph ascorbate following the salicylate-induced tinnitus and can thus be useful for investigation on chemical essences involved in tinnitus.
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Affiliation(s)
- Junxiu Liu
- Department of Otorhinolaryngology, Peking University Third Hospital, Beijing 100083, P. R. China
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50
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Le Prell CG, Dolan DF, Bennett DC, Boxer PA. Nutrient plasma levels achieved during treatment that reduces noise-induced hearing loss. Transl Res 2011; 158:54-70. [PMID: 21708356 PMCID: PMC3125531 DOI: 10.1016/j.trsl.2011.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 02/04/2011] [Accepted: 02/07/2011] [Indexed: 10/18/2022]
Abstract
Hearing loss encompasses both temporary and permanent deficits. If temporary threshold shift (TTS) and permanent threshold shift (PTS) share common pathological mechanisms, then agents that reduce PTS also should reduce TTS. Several antioxidant agents have reduced PTS in rodent models; however, reductions in TTS have been inconsistent. This study first determined whether dietary antioxidants (beta-carotene and vitamins C and E) delivered in combination with magnesium (Mg) reliably increase plasma concentrations of the active agents. Then, additional manipulations tested the hypothesis that these nutrients reduce acute TTS insult in the first 24 h after loud sound as well as longer lasting changes in hearing measured up to 7 days postnoise. Saline or nutrients were administered to guinea pigs prior to and after noise exposure. Sound-evoked electrophysiological responses were measured before noise, with tests repeated 1-h postnoise, as well as 1-day, 3-days, 5-days, and 7-days postnoise. All subjects showed significant functional recovery; subjects treated with nutrients recovered more rapidly and had better hearing outcomes at early postnoise times as well as the final test time. Thus, this combination of nutrients, which produced significant increases in plasma concentrations of vitamins C and E and Mg, effectively reduced hearing loss at multiple postnoise times. These data suggest that free radical formation contributes to TTS as well as PTS insults and suggest a potential opportunity to prevent TTS in human populations.
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Affiliation(s)
- Colleen G Le Prell
- Department of Speech, Language, and Hearing Sciences, University of Florida, Gainesville, FL 32610, USA.
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