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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] [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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2
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Luo Y, Chen A, Xu M, Chen D, Tang J, Ma D, Zhang H. Preparation, characterization, and in vitro/ vivo evaluation of dexamethasone/poly(ε-caprolactone)-based electrode coatings for cochlear implants. Drug Deliv 2021; 28:1673-1684. [PMID: 34347538 PMCID: PMC8344245 DOI: 10.1080/10717544.2021.1960927] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
With dexamethasone as the model drug and polycaprolactone (PCL) as the carrier material, a drug delivery coating for cochlear electrodes was prepared, to control cochlear fibrosis caused by cochlear implantation. A dexamethasone/poly (ε-caprolactone)-based electrode coating was prepared using the impregnation coating method. Preparation parameters were optimized, yielding 1 impregnation instance, impregnation time of 10 s, and PCL concentration of 10%. The coating was characterized in vitro using scanning electron microscopy, a universal machine, high-performance liquid chromatography, and CCK-8. The surface was porous and uniformly thick (average thickness, 48.67 µm)—with good flexibility, long-term slow drug release, and optimal drug concentration—and was biologically safe. The experimental results show that PCL is an ideal controlled-release material for dexamethasone as a drug carrier coating for cochlear implants.
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Affiliation(s)
- Yanjing Luo
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Muqing Xu
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Dongxiu Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Jie Tang
- Hearing Research Center, Southern Medical University, Guangzhou, China.,Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Dong Ma
- Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, China
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
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3
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Perez E, Viziano A, Al-Zaghal Z, Telischi FF, Sangaletti R, Jiang W, Dietrich WD, King C, Hoffer ME, Rajguru SM. Anatomical Correlates and Surgical Considerations for Localized Therapeutic Hypothermia Application in Cochlear Implantation Surgery. Otol Neurotol 2020; 40:1167-1177. [PMID: 31318786 PMCID: PMC6750193 DOI: 10.1097/mao.0000000000002373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Application of localized, mild therapeutic hypothermia during cochlear implantation (CI) surgery is feasible for residual hearing preservation.
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Affiliation(s)
| | - Andrea Viziano
- Department of Otolaryngology.,Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
| | | | | | | | - Weitao Jiang
- Department of Biomedical Engineering, University of Miami, Miami, Florida
| | - William Dalton Dietrich
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Miami, Florida
| | | | | | - Suhrud M Rajguru
- Department of Otolaryngology.,Department of Biomedical Engineering, University of Miami, Miami, Florida
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4
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Simoni E, Gentilin E, Candito M, Borile G, Romanato F, Chicca M, Nordio S, Aspidistria M, Martini A, Cazzador D, Astolfi L. Immune Response After Cochlear Implantation. Front Neurol 2020; 11:341. [PMID: 32477241 PMCID: PMC7240074 DOI: 10.3389/fneur.2020.00341] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/07/2020] [Indexed: 12/20/2022] Open
Abstract
A cochlear implant (CI) is an electronic device that enables hearing recovery in patients with severe to profound hearing loss. Although CIs are a successful treatment for profound hearing impairment, their effectivity may be improved by reducing damages associated with insertion of electrodes in the cochlea, thus preserving residual hearing ability. Inner ear trauma leads to inflammatory reactions altering cochlear homeostasis and reducing post-operative audiological performances and electroacoustic stimulation. Strategies to preserve residual hearing ability led to the development of medicated devices to minimize CI-induced cochlear injury. Dexamethasone-eluting electrodes recently showed positive outcomes. In previous studies by our research group, intratympanic release of dexamethasone for 14 days was able to preserve residual hearing from CI insertion trauma in a Guinea pig model. Long-term effects of dexamethasone-eluting electrodes were therefore evaluated in the same animal model. Seven Guinea pigs were bilaterally implanted with medicated rods and four were implanted with non-eluting ones. Hearing threshold audiograms were acquired prior to implantation and up to 60 days by recording compound action potentials. For each sample, we examined the amount of bone and fibrous connective tissue grown within the scala tympani in the basal turn of the cochlea, the cochleostomy healing, the neuronal density, and the correlation between electrophysiological parameters and histological results. Detection of tumor necrosis factor alpha, interleukin-6, and foreign body giant cells showed that long-term electrode implantation was not associated with an ongoing inflammation. Growth of bone and fibrous connective tissue around rods induced by CI was reduced in the scala tympani by dexamethasone release. For cochleostomy sealing, dexamethasone-treated animals showed less bone tissue growth than negative. Dexamethasone did not affect cell density in the spiral ganglion. Overall, these results support the use of dexamethasone as anti-inflammatory additive for eluting electrodes able to protect the cochlea from CI insertion trauma.
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Affiliation(s)
- Edi Simoni
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Erica Gentilin
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Mariarita Candito
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Giulia Borile
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Filippo Romanato
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Milvia Chicca
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Sara Nordio
- Fondazione Ospedale San Camillo IRCCS, Venice, Italy
| | - Marta Aspidistria
- Department of Statistical Sciences, University of Padua, Padova, Italy
| | - Alessandro Martini
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Diego Cazzador
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Laura Astolfi
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
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5
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Lithium niobate nanoparticles as biofunctional interface material for inner ear devices. Biointerphases 2020; 15:031004. [PMID: 32434336 DOI: 10.1116/6.0000067] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Sensorineural hearing loss (SNHL) affects the inner ear compartment and can be caused by different factors. Usually, the lack, death, or malfunction of sensory cells deputed to transduction of mechanic-into-electric signals leads to SNHL. To date, the therapeutic option for patients impaired by severe or profound SNHL is the cochlear implant (CI), a high-tech electronic device replacing the entire cochlear function. Piezoelectric materials have catalyzed attention to stimulate the auditory neurons by simply mimicking the function of the cochlear sensory epithelium. In this study, the authors investigated lithium niobate (LiNbO3) as a potential candidate material for next generation CIs. LiNbO3 nanoparticles resulted otocompatible with inner ear cells in vitro, had a pronounced immunomodulatory activity, enhanced human beta-defensin in epithelial cells, and showed direct antibacterial activity against P. aeruginosa. Moreover, LiNbO3 nanoparticles were incorporated into poly(vinylidene fluoride-trifluoro ethylene) fibers via electrospinning, which enhanced the piezoelectric response. Finally, the resulting fibrous composite structures support human neural-like cell growth in vitro, thus showing promising features to be used in new inner ear devices.
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Liebau A, Schilp S, Mugridge K, Schön I, Kather M, Kammerer B, Tillein J, Braun S, Plontke SK. Long-Term in vivo Release Profile of Dexamethasone-Loaded Silicone Rods Implanted Into the Cochlea of Guinea Pigs. Front Neurol 2020; 10:1377. [PMID: 32038458 PMCID: PMC6987378 DOI: 10.3389/fneur.2019.01377] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/13/2019] [Indexed: 11/29/2022] Open
Abstract
Glucocorticoids are used intra-operatively in cochlear implant surgeries to reduce the inflammatory reaction caused by insertion trauma and the foreign body response against the electrode carrier after cochlear implantation. To prevent higher systemic concentrations of glucocorticoids that might cause undesirable systemic side effects, the drug should be applied locally. Since rapid clearance of glucocorticoids occurs in the inner ear fluid spaces, sustained application is supposedly more effective in suppressing foreign body and tissue reactions and in preserving neuronal structures. Embedding of the glucocorticoid dexamethasone into the cochlear implant electrode carrier and its continuous release may solve this problem. The aim of the present study was to examine how dexamethasone concentrations in the electrode carrier influence drug levels in the perilymph at different time points. Silicone rods were implanted through a cochleostomy into the basal turn of the scala tympani of guinea pigs. The silicone rods were loaded homogeneously with 0.1, 1, and 10% concentrations of dexamethasone. After implantation, dexamethasone concentrations in perilymph and cochlear tissue were measured at several time points over a period of up to 7 weeks. The kinetic was concentration-dependent and showed an initial burst release in the 10%- and the 1%-dexamethasone-loaded electrode carrier dummies. The 10%-loaded electrode carrier resulted in a more elevated and longer lasting burst release than the 1%-loaded carrier. Following this initial burst release phase, sustained dexamethasone levels of about 60 and 100 ng/ml were observed in the perilymph for the 1 and 10% loaded rods, respectively, during the remainder of the observation time. The 0.1% loaded carrier dummy achieved very low perilymph drug levels of about 0.5 ng/ml. The cochlear tissue drug concentration shows a similar dynamic to the perilymph drug concentration, but only reaches about 0.005–0.05% of the perilymph drug concentration. Dexamethasone can be released from silicone electrode carrier dummies in a controlled and sustained way over a period of several weeks, leading to constant drug concentrations in the scala tympani perilymph. No accumulation of dexamethasone was observed in the cochlear tissue. In consideration of experimental studies using similar drug depots and investigating physiological effects, an effective dose range between 50 and 100 ng/ml after burst release is suggested for the CI insertion trauma model.
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Affiliation(s)
- Arne Liebau
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle, Germany
| | | | | | - Ilona Schön
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Michel Kather
- Center for Biological Systems Analysis ZBSA, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,Hermann Staudinger Graduate School, University of Freiburg, Freiburg, Germany
| | - Bernd Kammerer
- Center for Biological Systems Analysis ZBSA, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | | | | | - Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle, Germany
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Simoni E, Valente F, Boge L, Eriksson M, Gentilin E, Candito M, Cazzador D, Astolfi L. Biocompatibility of glycerol monooleate nanoparticles as tested on inner ear cells. Int J Pharm 2019; 572:118788. [DOI: 10.1016/j.ijpharm.2019.118788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/13/2022]
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8
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Lehner E, Gündel D, Liebau A, Plontke S, Mäder K. Intracochlear PLGA based implants for dexamethasone release: Challenges and solutions. INTERNATIONAL JOURNAL OF PHARMACEUTICS-X 2019; 1:100015. [PMID: 31517280 PMCID: PMC6733303 DOI: 10.1016/j.ijpx.2019.100015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 11/19/2022]
Abstract
The effective treatment of diseases of the inner ear is currently an unmet medical need. Local controlled drug delivery to the cochlea is challenging due to the hidden location, small volume and high sensitivity of this organ. A local intracochlear delivery of drugs would avoid the problems of intratympanic (extracochlear) drug application, but is more invasive. The requirements for such a delivery system include a small size and appropriate flexibility. The delivery device must be rigid enough for surgical handling but also flexible to avoid traumatizing cochlear structures. We developed biodegradable dexamethasone loaded PLGA extrudates for the controlled intracochlear release. In order to achieve the desired flexibility, Polyethylene glycol (PEG) was used as a plasticizer. In addition to the drug release, the extrudates were characterized in vitro by differential scanning calorimetry (DSC) and texture analysis. Simulation of the pharmacokinetics of the inner ear support the expectation that a constant perilymph drug level is obtained after few hours and retained over several weeks. Ex vivo implantation of the extrudates into a guinea pig cochlea indicate that PEG containing extrudates have the desired balance between mechanical strength and flexibility for direct implantation into the cochlea. The location of the implant was visualized by computer tomography. In summary, we postulate that intracochlear administration of drug releasing biodegradable implants is a new and promising approach to achieve local drug delivery to the cochlea for an extended time.
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Affiliation(s)
- E. Lehner
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany
| | - D. Gündel
- Department of Nuclear Medicine, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany
| | - A. Liebau
- Department of Otorhinolaryngology-Head and Neck Surgery, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany
| | - S. Plontke
- Department of Otorhinolaryngology-Head and Neck Surgery, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany
| | - K. Mäder
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany
- Corresponding author.
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9
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Zhang X, Geven MA, Wang X, Qin L, Grijpma DW, Peijs T, Eglin D, Guillaume O, Gautrot JE. A drug eluting poly(trimethylene carbonate)/poly(lactic acid)-reinforced nanocomposite for the functional delivery of osteogenic molecules. Int J Nanomedicine 2018; 13:5701-5718. [PMID: 30288042 PMCID: PMC6161751 DOI: 10.2147/ijn.s163219] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Background Poly(trimethylene carbonate) (PTMC) has wide biomedical applications in the field of tissue engineering, due to its biocompatibility and biodegradability features. Its common manufacturing involves photofabrication, such as stereolithography (SLA), which allows the fabrication of complex and controlled structures. Despite the great potential of SLA-fabricated scaffolds, very few examples of PTMC-based drug delivery systems fabricated using photo-fabrication can be found ascribed to light-triggered therapeutics instability, degradation, side reaction, binding to the macromers, etc. These concerns severely restrict the development of SLA-fabricated PTMC structures for drug delivery purposes. Methods In this context, we propose here, as a proof of concept, to load a drug model (dexamethasone) into electrospun fibers of poly(lactic acid), and then to integrate these bioactive fibers into the photo-crosslinkable resin of PTMC to produce hybrid films. The hybrid films' properties and drug release profile were characterized; its biological activity was investigated via bone marrow mesenchymal stem cells culture and differentiation assays. Results The polymer/polymer hybrids exhibit improved properties compared with PTMC-only films, in terms of mechanical performance and drug protection from UV denaturation. We further validated that the dexamethasone preserved its biological activity even after photoreaction within the PTMC/poly(lactic acid) hybrid structures by investigating bone marrow mesenchymal stem cells proliferation and osteogenic differentiation. Conclusion This study demonstrates the potential of polymer-polymer scaffolds to simultaneously reinforce the mechanical properties of soft matrices and to load sensitive drugs in scaffolds that can be fabricated via additive manufacturing.
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Affiliation(s)
- Xi Zhang
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, UK, .,Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, UK,
| | - Mike A Geven
- Department of Biomaterials Science and Technology, University of Twente, Enschede, the Netherlands
| | - Xinluan Wang
- Translational Medicine R&D Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 5018057, China
| | - Ling Qin
- Translational Medicine R&D Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 5018057, China
| | - Dirk W Grijpma
- Department of Biomaterials Science and Technology, University of Twente, Enschede, the Netherlands
| | - Ton Peijs
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, UK,
| | - David Eglin
- AO Research Institute Davos, Davos, Switzerland,
| | | | - Julien E Gautrot
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, UK, .,Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, UK,
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10
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Valente F, Astolfi L, Simoni E, Danti S, Franceschini V, Chicca M, Martini A. Nanoparticle drug delivery systems for inner ear therapy: An overview. J Drug Deliv Sci Technol 2017. [DOI: 10.1016/j.jddst.2017.03.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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Murillo-Cuesta S, Vallecillo N, Cediel R, Celaya AM, Lassaletta L, Varela-Nieto I, Contreras J. A Comparative Study of Drug Delivery Methods Targeted to the Mouse Inner Ear: Bullostomy Versus Transtympanic Injection. J Vis Exp 2017. [PMID: 28362376 PMCID: PMC5407703 DOI: 10.3791/54951] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We present two minimally invasive microsurgical techniques in rodents for specific drug delivery into the middle ear so that it may reach the inner ear. The first procedure consists of perforation of the tympanic bulla, termed bullostomy; the second one is a transtympanic injection. Both emulate human clinical intratympanic procedures. Chitosan-glycerophosphate (CGP) and Ringer´s Lactate buffer (RL) were used as biocompatible vehicles for local drug delivery. CGP is a nontoxic biodegradable polymer widely used in pharmaceutical applications. It is a viscous liquid at RT but it congeals to a semi solid phase at body temperature. RL is an isotonic solution used for intravenous administrations in humans. A small volume of this vehicle is precisely placed on the Round Window (RW) niche by means of a bullostomy. A transtympanic injection fills the middle ear and allows less control but broader access to the inner ear. The safety profiles of both techniques were studied and compared by using functional and morphological tests. Hearing was evaluated by registering the Auditory Brainstem Response (ABR) before and several times after microsurgery. The cytoarchitecture and preservation level of cochlear structures were studied by conventional histological techniques in paraformaldehyde-fixed and decalcified cochlear samples. In parallel, unfixed cochlear samples were taken and immediately frozen to analyze gene expression profiles of inflammatory markers by quantitative Reverse Transcriptase Polymerase Chain Reaction (qRT-PCR). Both procedures are suitable as drug delivery methods into the mouse middle ear, although transtympanic injection proved to be less invasive compared to bullostomy.
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Affiliation(s)
- Silvia Murillo-Cuesta
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII); Instituto de Investigación Sanitaria La Paz (IdiPAZ);
| | - Néstor Vallecillo
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM
| | - Rafael Cediel
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII); Facultad de Veterinaria, Universidad Complutense de Madrid
| | - Adelaida M Celaya
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII)
| | - Luis Lassaletta
- Instituto de Investigación Sanitaria La Paz (IdiPAZ); Departmento de Otorrino laringología, Hospital Universitario La Paz
| | - Isabel Varela-Nieto
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII); Instituto de Investigación Sanitaria La Paz (IdiPAZ)
| | - Julio Contreras
- Instituto de Investigaciones Biomédicas (IIBm) Alberto Sols CSIC-UAM; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII); Facultad de Veterinaria, Universidad Complutense de Madrid
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12
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Multifunctional hydrogel coatings on the surface of neural cuff electrode for improving electrode-nerve tissue interfaces. Acta Biomater 2016; 39:25-33. [PMID: 27163406 DOI: 10.1016/j.actbio.2016.05.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/18/2016] [Accepted: 05/03/2016] [Indexed: 01/12/2023]
Abstract
UNLABELLED Recently, implantable neural electrodes have been developed for recording and stimulation of the nervous system. However, when the electrode is implanted onto the nerve trunk, the rigid polyimide has a risk of damaging the nerve and can also cause inflammation due to a mechanical mismatch between the stiff polyimide and the soft biological tissue. These processes can interrupt the transmission of nerve signaling. In this paper, we have developed a nerve electrode coated with PEG hydrogel that contains poly(lactic-co-glycolic) acid (PLGA) microspheres (MS) loaded with anti-inflammatory cyclosporin A (CsA). Micro-wells were introduced onto the electrode in order to increase their surface area. This allows for loading a high-dose of the drug. Additionally, chemically treating the surface with aminopropylmethacrylamide can improve the adhesive interface between the electrode and the hydrogel. The surface of the micro-well cuff electrode (MCE) coated with polyethylene glycol (PEG) hydrogel and drug loaded PLGA microspheres (MS) were characterized by SEM and optical microscopy. Additionally, the conductive polymers, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT/PSS), were formed on the hydrogel layer for improving the nerve signal quality, and then characterized for their electrochemical properties. The loading efficiencies and release profiles were investigated by High Performance Liquid Chromatography (HPLC). The drug loaded electrode resulted in a sustained release of CsA. Moreover, the surface coated electrode with PEG hydrogel and CsA loaded MP showed a significantly decreased fibrous tissue deposition and increased axonal density in animal tests. We expect that the developed nerve electrode will minimize the tissue damage during regeneration of the nervous system. STATEMENT OF SIGNIFICANCE The nerve electrodes are used for interfacing with the central nervous system (CNS) or with the peripheral nervous system (PNS). The interface electrodes should facilitate a closed interconnection with the nerve tissue and provide for selective stimulation and recording from multiple, independent, neurons of the neural system. In this case, an extraneural electrodes such as cuff and perineural electrodes are widely investigated because they can completely cover the nerve trunk and provide for a wide interface area. In this study, we have designed and prepared a functionalized nerve cuff electrode coated with PEG hydrogel containing Poly lactic-co-glycol acid (PLGA) microspheres (MS) loaded with cyclosporine A (CsA). To our knowledge, our findings suggest that surface coating a soft-hydrogel along with an anti-inflammatory drug loaded MS can be a useful strategy for improving the long-term biocompatibility of electrodes.
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Gu P, Jiang Y, Gao X, Huang S, Yuan Y, Wang G, Li B, Xi X, Dai P. Effects of cochlear implant surgical technique on post-operative electrode impedance. Acta Otolaryngol 2016; 136:677-81. [PMID: 27049336 DOI: 10.3109/00016489.2016.1143967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSIONS The mCI surgical technique led to reduced impedance and minimized disturbance of the microenvironment inside the cochlea. Atraumatic surgical techniques and inflammation-reduction strategies may preserve the cochlear architecture and prevent fibrotic development. OBJECTIVES To assess the advantages of a modified minimal access technique in cochlear implantation as well as to investigate the effects of intra-operative application of inflammation reduction strategies on the intra-cochlear impedance. METHODS One hundred patients received a 31.5 mm long Med-El standard electrode array fully inserted into the cochlea and did not have surgical complications post-operation. Patients were divided into two groups according to the surgical technique that was used for implantation: 50 were in the modified minimal access cochlear implant (mCI) surgery group and 50 were in the traditional CI surgery group. Intra-cochlear impedance values were measured at initial activation (4 weeks post-operatively). Electrode impedance values were compared between the surgery groups. RESULTS Electrode impedance values were significantly lower in the mCI group than in the CI surgery group at initial activation (5.01 kOhm vs 6.10 kOhm, respectively, F = 13.761, p = 0.000). The differences between the two groups were most prominent for the electrodes located at the basal region of the cochlea.
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Astolfi L, Simoni E, Giarbini N, Giordano P, Pannella M, Hatzopoulos S, Martini A. Cochlear implant and inflammation reaction: Safety study of a new steroid-eluting electrode. Hear Res 2016; 336:44-52. [PMID: 27109196 DOI: 10.1016/j.heares.2016.04.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 03/30/2016] [Accepted: 04/18/2016] [Indexed: 12/20/2022]
Abstract
Dexamethasone is a common anti-inflammatory agent added to cochlear implants to reduce hearing loss due to electrode insertion trauma. We evaluated the safety of eluting silicone rods containing 10% dexamethasone in a Guinea pig model. Animals were implanted with a dexamethasone eluting silicone electrode (DER) or with a non-eluting electrode (NER). The control group only underwent a cochleostomy (CS). Prior to implantation and during the two weeks following implantation, the hearing status of the animals was assessed by means of Compound Action Potentials (CAPs) with an electrode placed near the round window. Two weeks after implantation, the mean click threshold shifts were 1 dB ± 10 dB in the DER group, 10 dB ± 10 dB in the NER group and -4 dB ± 10 dB in the control group. After two weeks the bullae of each animal were extracted to verify the presence of macrophages, the percent of tissue growth in the scala tympani and the tissue sealing around cochleostomy. Silicone electrodes samples were also explanted and examined for bacterial infection. Neither bacterial infection nor enhanced number of macrophages were observed. A limited, but not significant, tissue growth was found in the scala tympani between the experimental and the control group. The data suggest that, in the Guinea pig model, the use of DER is apparently safe as an anti-inflammatory slow-release additive to the cochlear implant.
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Affiliation(s)
- L Astolfi
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy.
| | - E Simoni
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy.
| | - N Giarbini
- ENT - Head and Neck Surgery Department, F. Tappeiner Hospital, Via Rossini 5, 39012, Merano, BZ, Italy.
| | - P Giordano
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy.
| | - M Pannella
- Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, 91120, Jerusalem, Israel.
| | - S Hatzopoulos
- ENT & Audiology Department, University Hospital of Ferrara, Via Aldo Moro 8, 44124, Cona, Ferrara, Italy.
| | - A Martini
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Via G. Orus, 2/B, 35129, Padua, Italy; ENT Surgery - Department of Neurosciences, University of Padua, Via Giustiniani 2, 35129, Padua, Italy.
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Beiter AL, Nel E. The history of Cochlear™ Nucleus ® sound processor upgrades: 30 years and counting. J Otol 2015; 10:108-114. [PMID: 29937792 PMCID: PMC6002568 DOI: 10.1016/j.joto.2015.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 10/08/2015] [Accepted: 10/13/2015] [Indexed: 11/29/2022] Open
Abstract
To review developments in sound processors over the past 30 years that have resulted in significant improvements in outcomes for Nucleus® recipients.
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Affiliation(s)
- Anne L Beiter
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia
| | - Esti Nel
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia
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16
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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: 104] [Impact Index Per Article: 11.6] [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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Astolfi L, Simoni E, Martini A. OC-k3 cells, anin vitromodel for cochlear implant biocompatibility. HEARING BALANCE AND COMMUNICATION 2015. [DOI: 10.3109/21695717.2015.1063232] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Liu Y, Jolly C, Braun S, Janssen T, Scherer E, Steinhoff J, Ebenhoch H, Lohner A, Stark T, Kiefer J. Effects of a dexamethasone-releasing implant on cochleae: A functional, morphological and pharmacokinetic study. Hear Res 2015; 327:89-101. [PMID: 25987502 DOI: 10.1016/j.heares.2015.04.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 01/12/2023]
Abstract
AIM This study evaluated the impact of a dexamethasone-releasing silicone implant on hearing function preservation, cochlear morphology and perilymph pharmacokinetics after cochlear implantation. METHODS Guinea pigs were implanted unilaterally with silicone rods containing either 2% dexamethasone (DEXA group, n = 18) or no dexamethasone (control group, n = 17). Auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) were measured preoperatively and over 6 months postoperatively. Cochlear histology using standard hematoxylin and eosin (H&E) staining and tumor necrosis factor (TNF)-alpha staining was performed 1 month postoperatively. Twenty-two guinea pigs were involved in the pharmacokinetic study, and real-time drug concentrations in perilymph were investigated using high-performance liquid chromatography (HPLC). The Mann-Whitney U test (1-tailed) was used for statistical analyses. RESULTS ABR and DPOAE testing demonstrated decreased hearing function immediately postoperatively followed by a progressive hearing loss within the first day postoperatively. There was almost no observable hearing improvement in the control group from 1 week to 6 months postoperatively, but hearing levels in the DEXA group improved gradually from 1 week to 12 weeks. Hearing loss in the DEXA and control group was 5.0 ± 3.4 dB and 21.7 ± 5.3 dB, respectively at a 16-kHz stimulus frequency 6 months postoperatively. The difference in threshold shifts was present throughout all measured frequencies, and it was significant at 4-24 kHz. The morphological study revealed new fibrosis formation in the scala tympani, which encapsulated the implanted electrode. TNF-alpha positive staining in the cochleae of the DEXA group was less evident than the control group. The pharmacokinetic study revealed a peak perilymph concentration 30 min postoperatively and sustained dexamethasone release at least 1 week postoperatively. CONCLUSION Cochlear implants that incorporate dexamethasone can release drug chronically in the inner ear and induce significant long-term recovery and preservation of auditory function after implantation.
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Affiliation(s)
- Ya Liu
- Department of Otolaryngology-Head and Neck Surgery, Beijing Naval General Hospital, Beijing 100048, PR China
| | - Claude Jolly
- Electrode Research Section, MED-EL Medical Electronics, Innsbruck, Austria
| | | | - Thomas Janssen
- 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
| | - Jochen Steinhoff
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Harald Ebenhoch
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Andrea Lohner
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Thomas Stark
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jan Kiefer
- HNO-Zentrum Neupfarrplatz, 12/II, 93047 Regensburg, Germany.
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Ayoob AM, Borenstein JT. The role of intracochlear drug delivery devices in the management of inner ear disease. Expert Opin Drug Deliv 2014; 12:465-79. [PMID: 25347140 DOI: 10.1517/17425247.2015.974548] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Diseases of the inner ear include those of the auditory and vestibular systems, and frequently result in disabling hearing loss or vertigo. Despite a rapidly expanding pipeline of potential cochlear therapeutics, the inner ear remains a challenging organ for targeted drug delivery, and new technologies are required to deliver these therapies in a safe and efficacious manner. In addition to traditional approaches for direct inner ear drug delivery, novel microfluidics-based systems are under development, promising improved control over pharmacokinetics over longer periods of delivery, ultimately with application towards hair cell regeneration in humans. AREAS COVERED Advances in the development of intracochlear drug delivery systems are reviewed, including passive systems, active microfluidic technologies and cochlear prosthesis-mediated delivery. This article provides a description of novel delivery systems and their potential future clinical applications in treating inner ear disease. EXPERT OPINION Recent progresses in microfluidics and miniaturization technologies are enabling the development of wearable and ultimately implantable drug delivery microsystems. Progress in this field is being spurred by the convergence of advances in molecular biology, microfluidic flow control systems and models for drug transport in the inner ear. These advances will herald a new generation of devices, with near-term applications in preclinical models, and ultimately with human clinical use for a range of diseases of the inner ear.
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Wrzeszcz A, Steffens M, Balster S, Warnecke A, Dittrich B, Lenarz T, Reuter G. Hydrogel coated and dexamethasone releasing cochlear implants: quantification of fibrosis in guinea pigs and evaluation of insertion forces in a human cochlea model. J Biomed Mater Res B Appl Biomater 2014; 103:169-78. [PMID: 24811046 DOI: 10.1002/jbm.b.33187] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 04/05/2014] [Indexed: 12/18/2022]
Abstract
The insertion of cochlear implants (CIs) often causes fibrous tissue growth around the electrode, which leads to attenuation of function of CIs. Inhibition of fibrosis in vivo using dexamethasone (Dex) released from the implant base material (polydimethylsiloxane [PDMS]) coated with a protein repelling hydrogel (star-shaped polyethylene glycol prepolymer, sPEG) was, therefore, the aim of the study. PDMS filaments with Dex or sPEG were implanted into guinea pigs. The hearing status after implantation did not differ significantly in the treated groups. Using confocal laser scanning microscopy in transparent whole mount preparations, Dex, Dex/sPEG, as well as sPEG showed a tendency toward reduced formation of connective tissue around the implant. To apply such coatings for glass fibers for optical stimulation of the inner ear, insertion forces were measured into a human scala tympani model using fibers with sPEG coating. The results show that the hydrogel did not reduce insertion forces compared to the uncoated samples. However, PDMS-embedded fibers provide comparable insertion forces and depth to those measured with conventional CI electrodes, demonstrating the suitability of laser fibers for a minimal traumatic cochlear implantation.
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Affiliation(s)
- Antonina Wrzeszcz
- Department of Otolaryngology, Hannover Medical School, Hannover, 30625, Germany
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