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Szabo E, Hess-Dunning A. Irreversible, Self-Aligned Microfluidic Packaging for Chronic Implant Applications. JOURNAL OF MICROMECHANICS AND MICROENGINEERING : STRUCTURES, DEVICES, AND SYSTEMS 2021; 31:1-10. [PMID: 35431469 PMCID: PMC9009276 DOI: 10.1088/1361-6439/ac1994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Packaging is an often overlooked component in microfluidic devices for biomedical implant applications. Robust and reliable connectors to interface microscale and macroscale features are especially critical for chronic implant applications. Existing microfluidic packaging methods are incompatible with emerging polymeric materials designed to enhance device integration with the surrounding tissue. A microfluidic connector scheme was developed to promote compatibility with novel materials and implant applications. The connectors and an adhesive wax were printed on a scaffold via additive manufacturing processes. The low-temperature packaging process entailed bonding the connector to a polymer nanocomposite-based intracortical microfluidic probe using an adhesive wax. The robustness of the packaging was assessed by measuring the tensile and shear bond strengths of the connector-adhesive wax-polymer film interface. After soak testing for 4 weeks, the bond strength continued to exceed the force required to infuse fluids through the microfluidic channel. Further, the shear bond strength exceeded typical probe insertion forces by at least 10-fold. These results support the use of the connector and thermal bonding method as a viable option for chronic implant applications.
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Affiliation(s)
- Emily Szabo
- Case Western Reserve University, Cleveland, OH 44106, USA
| | - Allison Hess-Dunning
- Case Western Reserve University, Cleveland, OH 44106, USA
- Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
- Advanced Platform Technology Center, Cleveland, OH 44106, USA
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Forouzandeh F, Alfadhel A, Arevalo A, Borkholder DA. A review of peristaltic micropumps. SENSORS AND ACTUATORS. A, PHYSICAL 2021; 326:112602. [PMID: 35386682 PMCID: PMC8979372 DOI: 10.1016/j.sna.2021.112602] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
This report presents a review of progress on peristaltic micropumps since their emergence, which have been widely used in many research fields from biology to aeronautics. This paper summarizes different techniques that have been used to mimic this elegant physiological transport mechanism that is commonly found in nature. The analysis provides definitions of peristaltic micropumps and their different features, distinguishing them from other mechanical micropumps. Important parameters in peristalsis are presented, such as the operating frequency, stroke volume, and various actuation sequences, along with introducing design rules and analysis for optimizing actuation sequences. Actuation methods such as piezoelectric, motor, pneumatic, electrostatic, and thermal are discussed with their advantages and disadvantages for application in peristaltic micropumps. This review evaluates research efforts over the past 30 years with comparison of key features and outputs, and suggestions for future development. The analysis provides a starting point for researchers designing peristaltic micropumps for a broad range of applications.
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Affiliation(s)
- Farzad Forouzandeh
- Corresponding author at: Microsystem Engineering, Kate Gleason College of Engineering, Rochester Institute of Technology, 168 Lomb Memorial Drive, Rochester, NY 14623, USA.
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Forouzandeh F, Ahamed NN, Zhu X, Bazard P, Goyal K, Walton JP, Frisina RD, Borkholder DA. A Wirelessly Controlled Scalable 3D-Printed Microsystem for Drug Delivery. Pharmaceuticals (Basel) 2021; 14:538. [PMID: 34199855 PMCID: PMC8227156 DOI: 10.3390/ph14060538] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 05/27/2021] [Accepted: 05/31/2021] [Indexed: 11/23/2022] Open
Abstract
Here we present a 3D-printed, wirelessly controlled microsystem for drug delivery, comprising a refillable microreservoir and a phase-change peristaltic micropump. The micropump structure was inkjet-printed on the back of a printed circuit board around a catheter microtubing. The enclosure of the microsystem was fabricated using stereolithography 3D printing, with an embedded microreservoir structure and integrated micropump. In one configuration, the microsystem was optimized for murine inner ear drug delivery with an overall size of 19 × 13 × 3 mm3. Benchtop results confirmed the performance of the device for reliable drug delivery. The suitability of the device for long-term subcutaneous implantation was confirmed with favorable results of implantation of a microsystem in a mouse for six months. The drug delivery was evaluated in vivo by implanting four different microsystems in four mice, while the outlet microtubing was implanted into the round window membrane niche for infusion of a known ototoxic compound (sodium salicylate) at 50 nL/min for 20 min. Real-time shifts in distortion product otoacoustic emission thresholds and amplitudes were measured during the infusion, demonstrating similar results with syringe pump infusion. Although demonstrated for one application, this low-cost design and fabrication methodology is scalable for use in larger animals and humans for different clinical applications/delivery sites.
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Affiliation(s)
- Farzad Forouzandeh
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (K.G.)
| | - Nuzhet N. Ahamed
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (K.G.)
| | - Xiaoxia Zhu
- Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA; (X.Z.); (P.B.); (J.P.W.); (R.D.F.)
| | - Parveen Bazard
- Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA; (X.Z.); (P.B.); (J.P.W.); (R.D.F.)
| | - Krittika Goyal
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (K.G.)
| | - Joseph P. Walton
- Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA; (X.Z.); (P.B.); (J.P.W.); (R.D.F.)
- Department of Chemical, Biological & Materials Engineering, University of South Florida, Tampa, FL 33620, USA
- Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA
| | - Robert D. Frisina
- Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA; (X.Z.); (P.B.); (J.P.W.); (R.D.F.)
- Department of Chemical, Biological & Materials Engineering, University of South Florida, Tampa, FL 33620, USA
- Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33620, USA
| | - David A. Borkholder
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (K.G.)
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Forouzandeh F, Ahamed NN, Hsu MC, Walton JP, Frisina RD, Borkholder DA. A 3D-Printed Modular Microreservoir for Drug Delivery. MICROMACHINES 2020; 11:mi11070648. [PMID: 32629848 PMCID: PMC7407798 DOI: 10.3390/mi11070648] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/23/2020] [Accepted: 06/27/2020] [Indexed: 11/16/2022]
Abstract
Reservoir-based drug delivery microsystems have enabled novel and effective drug delivery concepts in recent decades. These systems typically comprise integrated storing and pumping components. Here we present a stand-alone, modular, thin, scalable, and refillable microreservoir platform as a storing component of these microsystems for implantable and transdermal drug delivery. Three microreservoir capacities (1, 10, and 100 µL) were fabricated with 3 mm overall thickness using stereolithography 3D-printing technology, enabling the fabrication of the device structure comprising a storing area and a refill port. A thin, preformed dome-shaped storing membrane was created by the deposition of parylene-C over a polyethylene glycol sacrificial layer, creating a force-free membrane that causes zero forward flow and insignificant backward flow (2% of total volume) due to membrane force. A septum pre-compression concept was introduced that enabled the realization of a 1-mm-thick septa capable of ~65000 leak-free refill punctures under 100 kPa backpressure. The force-free storing membrane enables using normally-open micropumps for drug delivery, and potentially improves the efficiency and precision of normally-closed micropumps. The ultra-thin septum reduces the thickness of refillable drug delivery devices, and is capable of thousands of leak-free refills. This modular and scalable device can be used for drug delivery in different laboratory animals and humans, as a sampling device, and for lab-on-a-chip and point-of-care diagnostics applications.
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Affiliation(s)
- Farzad Forouzandeh
- Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (M.-C.H.)
| | - Nuzhet N. Ahamed
- Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (M.-C.H.)
| | - Meng-Chun Hsu
- Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (M.-C.H.)
| | - Joseph P. Walton
- Department of Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33612, USA; (J.P.W.); (R.D.F.)
- Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Robert D. Frisina
- Department of Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33612, USA; (J.P.W.); (R.D.F.)
- Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33612, USA
- Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - David A. Borkholder
- Microsystems Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA; (F.F.); (N.N.A.); (M.-C.H.)
- Correspondence: ; Tel.: +1-585-475-6067
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Forouzandeh F, Zhu X, Alfadhel A, Ding B, Walton JP, Cormier D, Frisina RD, Borkholder DA. A nanoliter resolution implantable micropump for murine inner ear drug delivery. J Control Release 2019; 298:27-37. [PMID: 30690105 DOI: 10.1016/j.jconrel.2019.01.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/19/2018] [Accepted: 01/24/2019] [Indexed: 10/27/2022]
Abstract
Advances in protective and restorative biotherapies have created new opportunities to use site-directed, programmable drug delivery systems to treat auditory and vestibular disorders. Successful therapy development that leverages the transgenic, knock-in, and knock-out variants of mouse models of human disease requires advanced microsystems specifically designed to function with nanoliter precision and with system volumes suitable for implantation. Here we present results for a novel biocompatible, implantable, scalable, and wirelessly controlled peristaltic micropump. The micropump configuration included commercially available catheter microtubing (250 μm OD, 125 μm ID) that provided a biocompatible leak-free flow path while avoiding complicated microfluidic interconnects. Peristaltic pumping was achieved by sequentially compressing the microtubing via expansion and contraction of a thermal phase-change material located in three chambers integrated adjacent to the microtubing. Direct-write micro-scale printing technology was used to build the mechanical components of the micropump around the microtubing directly on the back of a printed circuit board assembly (PCBA). The custom PCBA was fabricated using standard commercial processes providing microprocessor control of actuation and Bluetooth wireless communication through an Android application. The results of in vitro characterization indicated that nanoliter resolution control over the desired flow rates of 10-100 nL/min was obtained by changing the actuation frequency. Applying 10× greater than physiological backpressures and ± 3 °C ambient temperature variation did not significantly affect flow rates. Three different micropumps were tested on six mice for in vivo implantation of the catheter microtubing into the round window membrane niche for infusion of a known ototoxic compound (sodium salicylate) at 50 nL/min for 20 min. Real-time shifts in distortion product otoacoustic emission thresholds and amplitudes were measured during the infusion. There were systematic increases in distortion product threshold shifts during the 20-min perfusions; the mean shift was 15 dB for the most basal region. A biocompatibility study was performed to evaluate material suitability for chronic subcutaneous implantation and clinical translational development. The results indicated that the micropump components successfully passed key biocompatibility tests. A micropump prototype was implanted for one month without development of inflammation or infection. Although tested here on the small murine cochlea, this low-cost design and fabrication methodology is scalable for use in larger animals and for clinical applications in children and adults by appropriate scaling of the microtubing diameter and actuator volume.
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Affiliation(s)
- Farzad Forouzandeh
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Xiaoxia Zhu
- Department of Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - Ahmed Alfadhel
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Bo Ding
- Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - Joseph P Walton
- Department of Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - Denis Cormier
- Department of Industrial and Systems Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Robert D Frisina
- Department of Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Department of Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Department of Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - David A Borkholder
- Department of Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USA.
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Frisina RD, Budzevich M, Zhu X, Martinez GV, Walton JP, Borkholder DA. Animal model studies yield translational solutions for cochlear drug delivery. Hear Res 2018; 368:67-74. [PMID: 29793764 PMCID: PMC6165691 DOI: 10.1016/j.heares.2018.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/17/2018] [Accepted: 05/03/2018] [Indexed: 11/18/2022]
Abstract
The field of hearing and deafness research is about to enter an era where new cochlear drug delivery methodologies will become more innovative and plentiful. The present report provides a representative review of previous studies where efficacious results have been obtained with animal models, primarily rodents, for protection against acute hearing loss such as acoustic trauma due to noise overexposure, antibiotic use and cancer chemotherapies. These approaches were initiated using systemic injections or oral administrations of otoprotectants. Now, exciting new options for local drug delivery, which opens up the possibilities for utilization of novel otoprotective drugs or compounds that might not be suitable for systemic use, or might interfere with the efficacious actions of chemotherapeutic agents or antibiotics, are being developed. These include interesting use of nanoparticles (with or without magnetic field supplementation), hydrogels, cochlear micropumps, and new transtympanic injectable compounds, sometimes in combination with cochlear implants.
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Affiliation(s)
- R D Frisina
- Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA.
| | - M Budzevich
- Small Animal Imaging Lab, Moffitt Cancer Center, Tampa, FL, USA
| | - X Zhu
- Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Medical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - G V Martinez
- Small Animal Imaging Lab, Moffitt Cancer Center, Tampa, FL, USA
| | - J P Walton
- Dept. Communication Sciences & Disorders, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA; Dept. Chemical & Biomedical Engineering, Global Center for Hearing & Speech Research, University of South Florida, Tampa, FL, USA
| | - D A Borkholder
- Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USA
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Frisina RD, Ding B, Zhu X, Walton JP. Age-related hearing loss: prevention of threshold declines, cell loss and apoptosis in spiral ganglion neurons. Aging (Albany NY) 2017; 8:2081-2099. [PMID: 27667674 PMCID: PMC5076453 DOI: 10.18632/aging.101045] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/08/2016] [Indexed: 12/18/2022]
Abstract
Age-related hearing loss (ARHL) -presbycusis - is the most prevalent neurodegenerative disease and number one communication disorder of our aged population; and affects hundreds of millions of people worldwide. Its prevalence is close to that of cardiovascular disease and arthritis, and can be a precursor to dementia. The auditory perceptual dysfunction is well understood, but knowledge of the biological bases of ARHL is still somewhat lacking. Surprisingly, there are no FDA-approved drugs for treatment. Based on our previous studies of human subjects, where we discovered relations between serum aldosterone levels and the severity of ARHL, we treated middle age mice with aldosterone, which normally declines with age in all mammals. We found that hearing thresholds and suprathreshold responses significantly improved in the aldosterone-treated mice compared to the non-treatment group. In terms of cellular and molecular mechanisms underlying this therapeutic effect, additional experiments revealed that spiral ganglion cell survival was significantly improved, mineralocorticoid receptors were upregulated via post-translational protein modifications, and age-related intrinsic and extrinsic apoptotic pathways were blocked by the aldosterone therapy. Taken together, these novel findings pave the way for translational drug development towards the first medication to prevent the progression of ARHL.
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Affiliation(s)
- Robert D Frisina
- Department Communication Sciences and Disorders, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA.,Department Chemical and Biomedical Engineering, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA
| | - Bo Ding
- Department Communication Sciences and Disorders, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA
| | - Xiaoxia Zhu
- Department Chemical and Biomedical Engineering, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA
| | - Joseph P Walton
- Department Communication Sciences and Disorders, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA.,Department Chemical and Biomedical Engineering, Global Center for Hearing and Speech Research, University of South Florida, Tampa FL, 33612, USA
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Johnson DG, Borkholder DA. Towards an Implantable, Low Flow Micropump That Uses No Power in the Blocked-Flow State. MICROMACHINES 2016; 7:E99. [PMID: 30404274 PMCID: PMC6189832 DOI: 10.3390/mi7060099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/26/2016] [Accepted: 05/20/2016] [Indexed: 11/25/2022]
Abstract
Low flow rate micropumps play an increasingly important role in drug therapy research. Infusions to small biological structures and lab-on-a-chip applications require ultra-low flow rates and will benefit from the ability to expend no power in the blocked-flow state. Here we present a planar micropump based on gallium phase-change actuation that leverages expansion during solidification to occlude the flow channel in the off-power state. The presented four chamber peristaltic micropump was fabricated with a combination of Micro Electro Mechanical System (MEMS) techniques and additive manufacturing direct write technologies. The device is 7 mm × 13 mm × 1 mm (<100 mm³) with the flow channel and exterior coated with biocompatible Parylene-C, critical for implantable applications. Controllable pump rates from 18 to 104 nL/min were demonstrated, with 11.1 ± 0.35 nL pumped per actuation at an efficiency of 11 mJ/nL. The normally-closed state of the gallium actuator prevents flow and diffusion between the pump and the biological system or lab-on-a-chip, without consuming power. This is especially important for implanted applications with periodic drug delivery regimens.
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Affiliation(s)
- Dean G Johnson
- Rochester Institute of Technology, Microsystems Engineering, Rochester, NY 14623, USA.
| | - David A Borkholder
- Rochester Institute of Technology, Microsystems Engineering, Rochester, NY 14623, USA.
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Frisina RD, Frisina DR. Physiological and neurobiological bases of age-related hearing loss: biotherapeutic implications. Am J Audiol 2015; 22:299-302. [PMID: 24018570 DOI: 10.1044/1059-0889(2013/13-0003)] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
PURPOSE The aim of this study was to highlight growing evidence of interactions between hormones and the structure and function of the auditory system. METHOD Recent studies implicating sex hormones and other natural hormones in the modulation of hearing status in age-related hearing loss were reviewed. RESULTS Progesterone, a sex hormone, has been shown to have negative effects on the hearing of older women and aging mice, whereas, in contrast, estrogen was found in some cases to have a positive influence. Aldosterone, used in studies of animal models of autoimmune hearing loss, slowed the progression of hearing loss. Follow-up studies in humans revealed that auditory measures varied as serum aldosterone levels shifted within the normal range, in otherwise healthy older subjects. This was true for simple as well as complex auditory tasks (i.e., sound spatial processing), suggesting benefits of aldosterone to postperipheral auditory processing as well. In addition, evidence suggests that this functional hearing improvement occurred in association with anatomical improvements to the stria vascularis--an important site of anatomical change in presbycusis. CONCLUSIONS Audiology is now at the point where the search for biomedical interventions to modulate or prevent age-related hearing loss can move forward. Such interventions would require multidisciplinary collaborative initiatives by researchers in such areas as drug development, anatomy, auditory physiological and perceptual testing, and drug microdelivery systems.
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Pararas EEL, Borkholder DA, Borenstein JT. Microsystems technologies for drug delivery to the inner ear. Adv Drug Deliv Rev 2012; 64:1650-60. [PMID: 22386561 DOI: 10.1016/j.addr.2012.02.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 02/06/2012] [Accepted: 02/15/2012] [Indexed: 12/20/2022]
Abstract
The inner ear represents one of the most technologically challenging targets for local drug delivery, but its clinical significance is rapidly increasing. The prevalence of sensorineural hearing loss and other auditory diseases, along with balance disorders and tinnitus, has spurred broad efforts to develop therapeutic compounds and regenerative approaches to treat these conditions, necessitating advances in systems capable of targeted and sustained drug delivery. The delicate nature of hearing structures combined with the relative inaccessibility of the cochlea by means of conventional delivery routes together necessitate significant advancements in both the precision and miniaturization of delivery systems, and the nature of the molecular and cellular targets for these therapies suggests that multiple compounds may need to be delivered in a time-sequenced fashion over an extended duration. Here we address the various approaches being developed for inner ear drug delivery, including micropump-based devices, reciprocating systems, and cochlear prosthesis-mediated delivery, concluding with an analysis of emerging challenges and opportunities for the first generation of technologies suitable for human clinical use. These developments represent exciting advances that have the potential to repair and regenerate hearing structures in millions of patients for whom no currently available medical treatments exist, a situation that requires them to function with electronic hearing augmentation devices or to live with severely impaired auditory function. These advances also have the potential for broader clinical applications that share similar requirements and challenges with the inner ear, such as drug delivery to the central nervous system.
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Affiliation(s)
- Erin E Leary Pararas
- Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, MA 02139, USA
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