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Sekiya T, Holley MC. Cell Transplantation to Restore Lost Auditory Nerve Function is a Realistic Clinical Opportunity. Cell Transplant 2021; 30:9636897211035076. [PMID: 34498511 PMCID: PMC8438274 DOI: 10.1177/09636897211035076] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hearing is one of our most important means of communication. Disabling hearing loss (DHL) is a long-standing, unmet problem in medicine, and in many elderly people, it leads to social isolation, depression, and even dementia. Traditionally, major efforts to cure DHL have focused on hair cells (HCs). However, the auditory nerve is also important because it transmits electrical signals generated by HCs to the brainstem. Its function is critical for the success of cochlear implants as well as for future therapies for HC regeneration. Over the past two decades, cell transplantation has emerged as a promising therapeutic option for restoring lost auditory nerve function, and two independent studies on animal models show that cell transplantation can lead to functional recovery. In this article, we consider the approaches most likely to achieve success in the clinic. We conclude that the structure and biochemical integrity of the auditory nerve is critical and that it is important to preserve the remaining neural scaffold, and in particular the glial scar, for the functional integration of donor cells. To exploit the natural, autologous cell scaffold and to minimize the deleterious effects of surgery, donor cells can be placed relatively easily on the surface of the nerve endoscopically. In this context, the selection of donor cells is a critical issue. Nevertheless, there is now a very realistic possibility for clinical application of cell transplantation for several different types of hearing loss.
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Affiliation(s)
- Tetsuji Sekiya
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
- Department of Neurological Surgery, Hikone Chuo Hospital, Hikone, Japan
- Tetsuji Sekiya, Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, 606-8507 Kyoto, Japan,.
| | - Matthew C. Holley
- Department of Biomedical Science, University of Sheffield, Firth Court, Sheffield, England
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Ma Y, Wise AK, Shepherd RK, Richardson RT. New molecular therapies for the treatment of hearing loss. Pharmacol Ther 2019; 200:190-209. [PMID: 31075354 DOI: 10.1016/j.pharmthera.2019.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
An estimated 466 million people suffer from hearing loss worldwide. Sensorineural hearing loss is characterized by degeneration of key structures of the sensory pathway in the cochlea such as the sensory hair cells, the primary auditory neurons and their synaptic connection to the hair cells - the ribbon synapse. Various strategies to protect or regenerate these sensory cells and structures are the subject of intensive research. Yet despite recent advances in our understandings of the capacity of the cochlea for repair and regeneration there are currently no pharmacological or biological interventions for hearing loss. Current research focusses on localized cochlear drug, gene and cell-based therapies. One of the more promising drug-based therapies is based on neurotrophic factors for the repair of the ribbon synapse after noise exposure, as well as preventing loss of primary auditory neurons and regrowth of the auditory neuron fibers after severe hearing loss. Drug therapy delivery technologies are being employed to address the specific needs of neurotrophin and other therapies for hearing loss that include the need for high doses, long-term delivery, localised or cell-specific targeting and techniques for their safe and efficacious delivery to the cochlea. Novel biomaterials are enabling high payloads of drugs to be administered to the cochlea with subsequent slow-release properties that are proving to be beneficial for treating hearing loss. In parallel, new gene therapy technologies are addressing the need for cell specificity and high efficacy for the treatment of both genetic and acquired hearing loss with promising reports of hearing recovery. Some biomaterials and cell therapies are being used in conjunction with the cochlear implant ensuring therapeutic benefit to the primary neurons during electrical stimulation. This review will introduce the auditory system, hearing loss and the potential for repair and regeneration in the cochlea. Drug delivery to the cochlea will then be reviewed, with a focus on new biomaterials, gene therapy technologies, cell therapy and the use of the cochlear implant as a vehicle for drug delivery. With the current pre-clinical research effort into therapies for hearing loss, including clinical trials for gene therapy, the future for the treatment for hearing loss is looking bright.
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Affiliation(s)
- Yutian Ma
- Bionics Institute, East Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Australia; University of Melbourne, Department of Chemical Engineering, Parkville, Victoria, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Robert K Shepherd
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia.
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Zhang ZJ, Guan HX, Yang K, Xiao BK, Liao H, Jiang Y, Zhou T, Hua QQ. Dose-dependent effects of ouabain on spiral ganglion neurons and Schwann cells in mouse cochlea. Acta Otolaryngol 2017; 137:1017-1023. [PMID: 28503992 DOI: 10.1080/00016489.2017.1324217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE This study aimed in fully investigating the toxicities of ouabain to mouse cochlea and the related cellular environment, and providing an optimal animal model system for cell transplantation in the treatment of auditory neuropathy (AN) and sensorineural hearing loss (SNHL). METHODS Different dosages of ouabain were applied to mouse round window. The auditory brainstem responses and distortion product otoacoustic emissions were used to evaluate the cochlear function. The immunohistochemical staining and cochlea surface preparation were performed to detect the spiral ganglion neurons (SGNs), Schwann cells and hair cells. RESULTS Ouabain at the dosages of 0.5 mM, 1 mM and 3 mM selectively and permanently destroyed SGNs and their functions, while leaving the hair cells relatively intact. Ouabain at 3 mM resulted in the most severe SGNs loss and induced significant loss of Schwann cells started as early as 7 days and with further damages at 14 and 30 days after ouabain exposure. CONCLUSIONS The application of ouabain to mouse round window induces damages of SGNs and Schwann cells in a dose- and time-dependent manner, this study established a reliable and accurate animal model system of AN and SNHL.
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Affiliation(s)
- Zhi-Jian Zhang
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Hong-Xia Guan
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Kun Yang
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Bo-Kui Xiao
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Hua Liao
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yang Jiang
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Tao Zhou
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Qing-Quan Hua
- Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
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Warnecke A, Mellott AJ, Römer A, Lenarz T, Staecker H. Advances in translational inner ear stem cell research. Hear Res 2017; 353:76-86. [PMID: 28571616 DOI: 10.1016/j.heares.2017.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 05/01/2017] [Accepted: 05/23/2017] [Indexed: 12/16/2022]
Abstract
Stem cell research is expanding our understanding of developmental biology as well as promising the development of new therapies for a range of different diseases. Within hearing research, the use of stem cells has focused mainly on cell replacement. Stem cells however have a broad range of other potential applications that are just beginning to be explored in the ear. Mesenchymal stem cells are an adult derived stem cell population that have been shown to produce growth factors, modulate the immune system and can differentiate into a wide variety of tissue types. Potential advantages of mesenchymal/adult stem cells are that they have no ethical constraints on their use. However, appropriate regulatory oversight seems necessary in order to protect patients from side effects. Disadvantages may be the lack of efficacy in many preclinical studies. But if proven safe and efficacious, they are easily translatable to clinical trials. The current review will focus on the potential application on mesenchymal stem cells for the treatment of inner ear disorders.
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Affiliation(s)
- Athanasia Warnecke
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl Neuberg-Str. 1, 30625, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation, Germany
| | - Adam J Mellott
- Department of Plastic Surgery, University of Kansas School of Medicine, Kansas City, KS, USA
| | - Ariane Römer
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl Neuberg-Str. 1, 30625, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl Neuberg-Str. 1, 30625, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation, Germany
| | - Hinrich Staecker
- Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, KS, USA.
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Dehkordi MB, Madjd Z, Chaleshtori MH, Meshkani R, Nikfarjam L, Kajbafzadeh AM. A Simple, Rapid, and Efficient Method for Isolating Mesenchymal Stem Cells from the Entire Umbilical Cord. Cell Transplant 2016; 25:1287-1297. [DOI: 10.3727/096368915x582769] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Several reports have been published on the isolation, culture, and identification of mesenchymal stem cells (MSCs) from different anatomical regions of the umbilical cord (UC). UC is suitable for standardizing methods of MSC isolation because it is a uniform source with high MSC numbers. Although the UC is considered a medical waste after childbirth, ethical issues for its use must be considered. An increased demand for MSCs in regenerative medicine has made scientists prioritize the development of MSC isolation methods. Several research groups are attempting to provide a large number of high-quality MSCs. In this study, we present a modulated explant/enzyme method (MEEM) to isolate the maximum number of MSCs from the entire UC. This method was established for the isolation of MSCs from different anatomical regions of the UC altogether. We could retrieve 6 to 10 million MSCs during 8 to 10 days of primary culture. After three passages, we could obtain 8–10 × 108 cells in 28–30 days. MSCs isolated by this method express CD73, CD90, CD105, and CD44, but they do not express hematopoietic markers CD34 and CD45 or the endothelial marker CD31. The genes SOX2, OCT4, and NANOG are expressed in isolated MSCs. The capacity of these MSCs to differentiate into adipocytes and osteocytes highlights their application in regenerative medicine. This method is simple, reproducible, and cost efficient. Moreover, this method is suitable for the production of a large number of high-quality MSCs from an UC in less than a month, to be used for cell therapy in an 80-kg person.
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Affiliation(s)
- Mehdi Banitalebi Dehkordi
- Cellular and Molecular Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran (IRI)
| | - Zahra Madjd
- Oncopathology Research Center and Dep Pathology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran (IRI)
| | | | - Reza Meshkani
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran (IRI)
| | - Laleh Nikfarjam
- Pediatric Urology Research Center, Section of Tissue Engineering and Stem Cells Therapy, Children's Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran (IRI)
| | - Abdol-Mohammad Kajbafzadeh
- Pediatric Urology Research Center, Section of Tissue Engineering and Stem Cells Therapy, Children's Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran (IRI)
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Jang S, Cho HH, Kim SH, Lee KH, Cho YB, Park JS, Jeong HS. Transplantation of human adipose tissue-derived stem cells for repair of injured spiral ganglion neurons in deaf guinea pigs. Neural Regen Res 2016; 11:994-1000. [PMID: 27482231 PMCID: PMC4962600 DOI: 10.4103/1673-5374.184503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2015] [Indexed: 12/30/2022] Open
Abstract
Excessive noise, ototoxic drugs, infections, autoimmune diseases, and aging can cause loss of spiral ganglion neurons, leading to permanent sensorineural hearing loss in mammals. Stem cells have been confirmed to be able to differentiate into spiral ganglion neurons. Little has been reported on adipose tissue-derived stem cells (ADSCs) for repair of injured spiral ganglion neurons. In this study, we hypothesized that transplantation of neural induced-human ADSCs (NI-hADSCs) can repair the injured spiral ganglion neurons in guinea pigs with neomycin-induced sensorineural hearing loss. NI-hADSCs were induced with culture medium containing basic fibroblast growth factor and forskolin and then injected to the injured cochleae. Guinea pigs that received injection of Hanks' balanced salt solution into the cochleae were used as controls. Hematoxylin-eosin staining showed that at 8 weeks after cell transplantation, the number of surviving spiral ganglion neurons in the cell transplantation group was significantly increased than that in the control group. Also at 8 weeks after cell transplantation, immunohistochemical staining showed that a greater number of NI-hADSCs in the spiral ganglions were detected in the cell transplantation group than in the control group, and these NI-hADSCs expressed neuronal markers neurofilament protein and microtubule-associated protein 2. Within 8 weeks after cell transplantation, the guinea pigs in the cell transplantation group had a gradually decreased auditory brainstem response threshold, while those in the control group had almost no response to 80 dB of clicks or pure tone burst. These findings suggest that a large amount of NI-hADSCs migrated to the spiral ganglions, survived for a period of time, repaired the injured spiral ganglion cells, and thereby contributed to the recovery of sensorineural hearing loss in guinea pigs.
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Affiliation(s)
- Sujeong Jang
- Department of Physiology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Hyong-Ho Cho
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Song-Hee Kim
- Department of Physiology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Kyung-Hwa Lee
- Department of Pathology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Yong-Bum Cho
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Jong-Seong Park
- Department of Physiology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Han-Seong Jeong
- Department of Physiology, Chonnam National University Medical School, Gwangju, Republic of Korea
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Efficacy of Human Adipose Tissue-Derived Stem Cells on Neonatal Bilirubin Encephalopathy in Rats. Neurotox Res 2016; 29:514-24. [PMID: 26818600 DOI: 10.1007/s12640-016-9599-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/04/2015] [Accepted: 12/28/2015] [Indexed: 10/22/2022]
Abstract
Kernicterus is a neurological syndrome associated with indirect bilirubin accumulation and damages to the basal ganglia, cerebellum and brain stem nuclei particularly the cochlear nucleus. To mimic haemolysis in a rat model such that it was similar to what is observed in a preterm human, we injected phenylhydrazine in 7-day-old rats to induce haemolysis and then infused sulfisoxazole into the same rats at day 9 to block bilirubin binding sites in the albumin. We have investigated the effectiveness of human adiposity-derived stem cells as a therapeutic paradigm for perinatal neuronal repair in a kernicterus animal model. The level of total bilirubin, indirect bilirubin, brain bilirubin and brain iron was significantly increased in the modelling group. There was a significant decreased in all severity levels of the auditory brainstem response test in the two modelling group. Akinesia, bradykinesia and slip were significantly declined in the experience group. Apoptosis in basal ganglia and cerebellum were significantly decreased in the stem cell-treated group in comparison to the vehicle group. All severity levels of the auditory brainstem response tests were significantly decreased in 2-month-old rats. Transplantation results in the substantial alleviation of walking impairment, apoptosis and auditory dysfunction. This study provides important information for the development of therapeutic strategies using human adiposity-derived stem cells in prenatal brain damage to reduce potential sensori motor deficit.
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Tona Y, Inaoka T, Ito J, Kawano S, Nakagawa T. Development of an electrode for the artificial cochlear sensory epithelium. Hear Res 2015; 330:106-12. [PMID: 26299844 DOI: 10.1016/j.heares.2015.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 08/11/2015] [Accepted: 08/17/2015] [Indexed: 11/28/2022]
Abstract
An artificial cochlear sensory epithelium has been developed on the basis of a new concept that the piezoelectric membrane, which converts mechanical distortion into electricity, can mimic the function of the inner hair cell and basilar membrane of the mammalian cochlea. Our previous research demonstrated that the piezoelectric membrane generated electrical outputs in response to the sound stimulation after implantation into the guinea pig cochlea, whereas electrodes for the stimulation of spiral ganglion neurons have not been fabricated, and a method to fix the device in the cochlea is also required to show proof-of-concept. In the present study, to achieve proof-of-concept of hearing recovery by implantation of the artificial cochlear sensory epithelium, we fabricated new electrodes that stick into the cochlear modiolus, which also play a role in the fixation of the device in the cochlea. The efficacy of new electrodes for fixation of the device in the cochlea and for the stimulation of spiral ganglion neurons was estimated in guinea pigs. Four weeks after implantation, we confirmed that the devices were in place. Histological analysis of the implanted cochleae revealed inconspicuous fibrosis and scar formation compared with the sham-operated specimens (n = 5 for each). The terminal deoxynucleotidyl transferase dUTP nick end labeling method was used to assess cell death due to surgical procedures in the cochleae that were harvested after 1 day (n = 6) and 7 days (n = 6) of implantation; there was no significant increase in apoptotic cell death in the implanted cochleae compared with sham-operated cochleae. In seven animals, serial measurements of electrically evoked auditory brainstem responses were obtained, with the electrode positioned in the scala tympani and with the electrode inserted into the cochlear modiolus. With the insertion of electrodes into the cochlear modiolus, significant reduction was achieved in the thresholds of electrically evoked auditory brainstem responses compared with those placed in the scala tympani (p = 0.028). These findings indicated that the new electrodes efficiently fixed the device in the cochlea and were able to stimulate spiral ganglion neurons.
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Affiliation(s)
- Yosuke Tona
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Takatoshi Inaoka
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan; Inaoka ENT Clinic, 2-1-14-201, Neyaminami, Neyagawa 572-0855, Japan.
| | - Juichi Ito
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Satoyuki Kawano
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
| | - Takayuki Nakagawa
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
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Hu Z, Ulfendahl M. The potential of stem cells for the restoration of auditory function in humans. Regen Med 2014; 8:309-18. [PMID: 23627825 DOI: 10.2217/rme.13.32] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hearing loss is one of the most common disabilities, affecting approximately 10% of the population. Hair cells and spiral ganglion neurons are usually damaged in most cases of hearing loss. Currently, there is virtually no biological approach to replace damaged hearing cells. Recent developments in stem cell technology provide new opportunities for the treatment of deafness. Two major strategies have been investigated: differentiation of endogenous stem cells into new hair cells; and introduction of exogenous cells into the inner ear to substitute injured hearing neurons. Although there is still a learning curve in stem cell-based replacement, the probability exists to utilize personalized stem cells to eventually provide a novel intervention for patients with deafness in future clinical research trials.
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Affiliation(s)
- Zhengqing Hu
- Department of Otolaryngology-HNS, Wayne State University, MI, USA.
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Needham K, Minter RL, Shepherd RK, Nayagam BA. Challenges for stem cells to functionally repair the damaged auditory nerve. Expert Opin Biol Ther 2013; 13:85-101. [PMID: 23094991 PMCID: PMC3543850 DOI: 10.1517/14712598.2013.728583] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION In the auditory system, a specialized subset of sensory neurons are responsible for correctly relaying precise pitch and temporal cues to the brain. In individuals with severe-to-profound sensorineural hearing impairment these sensory auditory neurons can be directly stimulated by a cochlear implant, which restores sound input to the brainstem after the loss of hair cells. This neural prosthesis therefore depends on a residual population of functional neurons in order to function effectively. AREAS COVERED In severe cases of sensorineural hearing loss where the numbers of auditory neurons are significantly depleted, the benefits derived from a cochlear implant may be minimal. One way in which to restore function to the auditory nerve is to replace these lost neurons using differentiated stem cells, thus re-establishing the neural circuit required for cochlear implant function. Such a therapy relies on producing an appropriate population of electrophysiologically functional neurons from stem cells, and on these cells integrating and reconnecting in an appropriate manner in the deaf cochlea. EXPERT OPINION Here we review progress in the field to date, including some of the key functional features that stem cell-derived neurons would need to possess and how these might be enhanced using electrical stimulation from a cochlear implant.
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Affiliation(s)
- Karina Needham
- University of Melbourne, Department of Otolaryngology, East Melbourne, Australia.
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Gunewardene N, Dottori M, Nayagam BA. The convergence of cochlear implantation with induced pluripotent stem cell therapy. Stem Cell Rev Rep 2012; 8:741-54. [PMID: 21956409 DOI: 10.1007/s12015-011-9320-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
According to 2010 estimates from The National Institute on Deafness and other Communication Disorders, approximately 17% (36 million) American adults have reported some degree of hearing loss. Currently, the only clinical treatment available for those with severe-to-profound hearing loss is a cochlear implant, which is designed to electrically stimulate the auditory nerve in the absence of hair cells. Whilst the cochlear implant has been revolutionary in terms of providing hearing to the severe-to-profoundly deaf, there are variations in cochlear implant performance which may be related to the degree of degeneration of auditory neurons following hearing loss. Hence, numerous experimental studies have focused on enhancing the efficacy of cochlear implants by using neurotrophins to preserve the auditory neurons, and more recently, attempting to replace these dying cells with new neurons derived from stem cells. As a result, several groups are now investigating the potential for both embryonic and adult stem cells to replace the degenerating sensory elements in the deaf cochlea. Recent advances in our knowledge of stem cells and the development of induced pluripotency by Takahashi and Yamanaka in 2006, have opened a new realm of science focused on the use of induced pluripotent stem (iPS) cells for therapeutic purposes. This review will provide a broad overview of the potential benefits and challenges of using iPS cells in combination with a cochlear implant for the treatment of hearing loss, including differentiation of iPS cells into an auditory neural lineage and clinically relevant transplantation approaches.
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Affiliation(s)
- Niliksha Gunewardene
- Department of Otolaryngology, University of Melbourne, Melbourne, Victoria, Australia
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Nayagam BA, Edge AS, Needham K, Hyakumura T, Leung J, Nayagam DAX, Dottori M. An in vitro model of developmental synaptogenesis using cocultures of human neural progenitors and cochlear explants. Stem Cells Dev 2012; 22:901-12. [PMID: 23078657 DOI: 10.1089/scd.2012.0082] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In mammals, the sensory hair cells and auditory neurons do not spontaneously regenerate and their loss results in permanent hearing impairment. Stem cell therapy is one emerging strategy that is being investigated to overcome the loss of sensory cells after hearing loss. To successfully replace auditory neurons, stem cell-derived neurons must be electrically active, capable of organized outgrowth of processes, and of making functional connections with appropriate tissues. We have developed an in vitro assay to test these parameters using cocultures of developing cochlear explants together with neural progenitors derived from human embryonic stem cells (hESCs). We found that these neural progenitors are electrically active and extend their neurites toward the sensory hair cells in cochlear explants. Importantly, this neurite extension was found to be significantly greater when neural progenitors were predifferentiated toward a neural crest-like lineage. When grown in coculture with hair cells only (denervated cochlear explants), stem cell-derived processes were capable of locating and growing along the hair cell rows in an en passant-like manner. Many presynaptic terminals (synapsin 1-positive) were observed between hair cells and stem cell-derived processes in vitro. These results suggest that differentiated hESC-derived neural progenitors may be useful for developing therapies directed at auditory nerve replacement, including complementing emerging hair cell regeneration therapies.
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Affiliation(s)
- Bryony A Nayagam
- Department of Otolaryngology, The University of Melbourne, Melbourne, Parkville, Australia.
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Eshraghi AA, Nazarian R, Telischi FF, Rajguru SM, Truy E, Gupta C. The cochlear implant: historical aspects and future prospects. Anat Rec (Hoboken) 2012; 295:1967-80. [PMID: 23044644 DOI: 10.1002/ar.22580] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 02/06/2023]
Abstract
The cochlear implant (CI) is the first effective treatment for deafness and severe losses in hearing. As such, the CI is now widely regarded as one of the great advances in modern medicine. This article reviews the key events and discoveries that led up to the current CI systems, and we review and present some among the many possibilities for further improvements in device design and performance. The past achievements include: (1) development of reliable devices that can be used over the lifetime of a patient; (2) development of arrays of implanted electrodes that can stimulate more than one site in the cochlea; and (3) progressive and large improvements in sound processing strategies for CIs. In addition, cooperation between research organizations and companies greatly accelerated the widespread availability and use of safe and effective devices. Possibilities for the future include: (1) use of otoprotective drugs; (2) further improvements in electrode designs and placements; (3) further improvements in sound processing strategies; (4) use of stem cells to replace lost sensory hair cells and neural structures in the cochlea; (5) gene therapy; (6) further reductions in the trauma caused by insertions of electrodes and other manipulations during implant surgeries; and (7) optical rather electrical stimulation of the auditory nerve. Each of these possibilities is the subject of active research. Although great progress has been made to date in the development of the CI, including the first substantial restoration of a human sense, much more progress seems likely and certainly would not be a surprise.
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Affiliation(s)
- Adrien A Eshraghi
- Department of Otolaryngology, University of Miami Ear Institute, University of Miami Miller School of Medicine, Miami, Florida 33136-1015, USA.
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Potential roles of stem cells in the management of sensorineural hearing loss. The Journal of Laryngology & Otology 2012; 126:653-7. [PMID: 22624825 DOI: 10.1017/s0022215112000850] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND In the management of sensorineural hearing loss, effective therapy for degenerated hair cells, third order neurons, ganglions, dendrites and synaptic areas of the vestibulo-cochleo-cerebral pathway remains an enigma. Transplantation of stem and progenitor cells appears to be an emerging potential solution, and is the focus of this review. AIM To review recent developments in the management of sensorineural hearing loss in the field of stem cell research. MATERIALS AND METHOD A systematic review of the English language literature included all experimental and non-experimental studies with a Jadad score of three or more, published between 2000 and 2010 and included in the following databases: Cochrane Library Ear, Nose and Throat Disorders; Medline; Google Scholar; Hinari; and the Online Library of Toronto University. RESULTS Of the 455 and 29 600 articles identified from Medline and Google Scholar, respectively, 48 met the inclusion criteria. These were independently reviewed and jointly analysed. CONCLUSION Although there is not yet any evidence from successful human studies, stem cell and 'alternative stem cell' technology seems to represent the future of sensorineural hearing loss management.
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Nayagam BA, Minter RL. A comparison of in vitro treatments for directing stem cells toward a sensory neural fate. Am J Otolaryngol 2012; 33:37-46. [PMID: 21439680 DOI: 10.1016/j.amjoto.2010.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 12/20/2010] [Indexed: 10/18/2022]
Abstract
PURPOSE Low numbers of primary auditory neurons (ANs) may compromise the clinical performance of a cochlear implant. The focus of this research is to determine whether stem cells can be used to replace the ANs lost following deafness. To successfully replace these neurons, stem cells must be capable of directed differentiation into a sensory neural lineage in vitro and, subsequently, of survival and integration into the deafened cochlea. MATERIALS AND METHODS In this study, we compared three in vitro treatments for directing the differentiation of mouse embryonic stem cells toward a sensory neural fate using neurotrophins, conditioned media from early post-natal cochlear epithelium, or media containing BMP4. RESULTS In all treatments, stem cells were first exposed to retinoic acid, which was sufficient to induce Brn3a-positive patterning in 8-day differentiated embryoid bodies. After a further 8 days of differentiation in adherent culture conditions, BMP4 media-treated cultures produced higher proportions of cells expressing sensory neural markers in comparison to both the conditioned media and neurotrophin treatments, including significantly greater numbers of cells expressing peripherin (P ≤ .001), tyrosine receptor kinase B (P ≤ .001), and β-III tubulin (P ≤ .001). CONCLUSIONS This study illustrated that combined treatment with retinoic acid and BMP4 was most effective at directing differentiation of mouse stem cells into sensory-like neurons in vitro. This finding further supports the role of bone morphogenetic proteins in the differentiation of sensory neurons from neural progenitors, and provides a basis for allotransplantation studies for auditory neuron replacement in the deaf mouse cochlea.
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Parker MA. Biotechnology in the treatment of sensorineural hearing loss: foundations and future of hair cell regeneration. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2011; 54:1709-1731. [PMID: 21386039 PMCID: PMC3163053 DOI: 10.1044/1092-4388(2011/10-0149)] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
PURPOSE To provide an overview of the methodologies involved in the field of hair cell regeneration. First, the author provides a tutorial on the biotechnological foundations of this field to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, the author presents a review of stem cell and gene therapy and provides a critical appraisal of their application to hair cell regeneration. The methodologies used in these approaches are highlighted. METHOD The author conducted a narrative review of the fields of cellular, molecular, and developmental biology, tissue engineering, and stem cell and gene therapy using the PubMed database. RESULTS The use of biotechnological approaches to the treatment of hearing loss--approaches such as stem cell and gene therapy-has led to new methods of regenerating cochlear hair cells in mammals. CONCLUSIONS Incredible strides have been made in assembling important pieces of the puzzle that comprise hair cell regeneration. However, mammalian hair cell regeneration using stem cell and gene therapy are years--if not decades--away from being clinically feasible. If the goals of the biological approaches are met, these therapies may represent future treatments for hearing loss.
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Kopecky B, Fritzsch B. Regeneration of Hair Cells: Making Sense of All the Noise. Pharmaceuticals (Basel) 2011; 4:848-879. [PMID: 21966254 PMCID: PMC3180915 DOI: 10.3390/ph4060848] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 06/04/2011] [Accepted: 06/08/2011] [Indexed: 12/17/2022] Open
Abstract
Hearing loss affects hundreds of millions of people worldwide by dampening or cutting off their auditory connection to the world. Current treatments for sensorineural hearing loss (SNHL) with cochlear implants are not perfect, leaving regenerative medicine as the logical avenue to a perfect cure. Multiple routes to regeneration of damaged hair cells have been proposed and are actively pursued. Each route not only requires a keen understanding of the molecular basis of ear development but also faces the practical limitations of stem cell regulation in the delicate inner ear where topology of cell distribution is essential. Improvements in our molecular understanding of the minimal essential genes necessary for hair cell formation and recent advances in stem cell manipulation, such as seen with inducible pluripotent stem cells (iPSCs) and epidermal neural crest stem cells (EPI-NCSCs), have opened new possibilities to advance research in translational stem cell therapies for individuals with hearing loss. Despite this, more detailed network maps of gene expression are needed, including an appreciation for the roles of microRNAs (miRs), key regulators of transcriptional gene networks. To harness the true potential of stem cells for hair cell regeneration, basic science and clinical medicine must work together to expedite the transition from bench to bedside by elucidating the full mechanisms of inner ear hair cell development, including a focus on the role of miRs, and adapting this knowledge safely and efficiently to stem cell technologies.
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Affiliation(s)
- Benjamin Kopecky
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
- Medical Scientist Training Program, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
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Cho YB, Cho HH, Jang S, Jeong HS, Park JS. Transplantation of neural differentiated human mesenchymal stem cells into the cochlea of an auditory-neuropathy guinea pig model. J Korean Med Sci 2011; 26:492-8. [PMID: 21468255 PMCID: PMC3069567 DOI: 10.3346/jkms.2011.26.4.492] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 02/08/2011] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to determine the effects of transplanted neural differentiated human mesenchymal stem cells (hMSCs) in a guinea pig model of auditory neuropathy. In this study, hMSCs were pretreated with a neural-induction protocol and transplanted into the scala tympani of the guinea pig cochlea 7 days after ouabain injury. A control model was made by injection of Hanks balanced salt solution alone into the scala tympani of the guinea pig cochlea 7 days after ouabain injury. We established the auditory neuropathy guinea pig model using 1 mM ouabain application to the round window niche. After application of ouabain to the round window niche, degeneration of most spiral ganglion neurons (SGNs) without the loss of hair cells within the organ of Corti and increasing the auditory brain responses (ABR) threshold were found. After transplantation of neural differentiated hMSCs, the number of SGNs was increased, and some of the SGNs expressed immunoreactivity with human nuclear antibody under confocal laser scanning microscopy. ABR results showed mild hearing recovery after transplantation. Based on an auditory neuropathy animal model, these findings suggest that it may be possible to replace degenerated SGNs by grafting stem cells into the scala tympani.
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Affiliation(s)
- Yong-Bum Cho
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju, Korea
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Hyong-Ho Cho
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju, Korea
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Sujeong Jang
- Department of Physiology, Chonnam National University Medical School, Gwangju, Korea
- Brain Korea 21 Project, Center for Biomedical Human Resources at Chonnam National University, Gwangju, Korea
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Han-Seong Jeong
- Department of Physiology, Chonnam National University Medical School, Gwangju, Korea
- Brain Korea 21 Project, Center for Biomedical Human Resources at Chonnam National University, Gwangju, Korea
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Jong-Seong Park
- Department of Physiology, Chonnam National University Medical School, Gwangju, Korea
- Brain Korea 21 Project, Center for Biomedical Human Resources at Chonnam National University, Gwangju, Korea
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
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Zhang L, Jiang H, Hu Z. Concentration-dependent effect of nerve growth factor on cell fate determination of neural progenitors. Stem Cells Dev 2011; 20:1723-31. [PMID: 21219132 DOI: 10.1089/scd.2010.0370] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Stem cell-based spiral ganglion neuron (SGN) replacement therapy has been proposed to be a promising strategy to restore hearing either via replacing degenerated neurons or by improving the efficacy of cochlear implants which rely on functional neurons. However, lack of suitable donor cells and low survival rate of implanted cells are the major obstacles to successful implementation of therapeutic transplantation. The present study investigated the potential of mouse inner ear statoacoustic ganglion (SAG)-derived neural progenitors (NPs) to differentiate toward SGN-like glutamatergic cells and the influence to cell survival and differentiation when nerve growth factor (NGF) was supplied. We found that SAG-NPs could form neurospheres, proliferate, and differentiate into cells expressing neuronal protein neurofilament and β-III tubulin. NGF affected the cell fate of SAG-NP in a concentration-dependent manner in vitro. Low concentration of NGF (2-5 ng/mL) promoted cell proliferation. Medium concentration of NGF (20-40 ng/mL) stimulated cells to differentiate into bi-polar SGN-like cells expressing glutamatergic proteins. High concentration of NGF (100 ng/mL) could rescue cells from induced apoptosis. In the in vivo study, NGF (100 ng/mL) dramatically enhanced SAG-NP survival rate after implantation into adult mammalian inner ear. This finding raises the possibility to further induce these NPs to differentiate into SGN-like neurons in future in vivo study. In conclusion, given the capability of proliferation and differentiation into SGN-like cells with the supplement of NGF in vitro, SAG-NPs can serve as donor cells in stem cell-based SGN replacement therapy. NGF improved the survival of SAG-NPs not only in vitro but also in vivo.
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Affiliation(s)
- Lei Zhang
- Department of Otolaryngology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Complex distribution patterns of voltage-gated calcium channel α-subunits in the spiral ganglion. Hear Res 2011; 278:52-68. [PMID: 21281707 DOI: 10.1016/j.heares.2011.01.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 01/21/2011] [Accepted: 01/21/2011] [Indexed: 01/10/2023]
Abstract
As with other elements of the peripheral auditory system, spiral ganglion neurons display specializations that vary as a function of location along the tonotopic axis. Previous work has shown that voltage-gated K(+) channels and synaptic proteins show graded changes in their density that confers rapid responsiveness to neurons in the high frequency, basal region of the cochlea and slower, more maintained responsiveness to neurons in the low frequency, apical region of the cochlea. In order to understand how voltage-gated calcium channels (VGCCs) may contribute to these diverse phenotypes, we identified the VGCC α-subunits expressed in the ganglion, investigated aspects of Ca(2+)-dependent neuronal firing patterns, and mapped the intracellular and intercellular distributions of seven VGCC α-subunits in the spiral ganglion in vitro. Initial experiments with qRT-PCR showed that eight of the ten known VGCC α-subunits were expressed in the ganglion and electrophysiological analysis revealed firing patterns that were consistent with the presence of both LVA and HVA Ca(2+) channels. Moreover, we were able to study seven of the α-subunits with immunocytochemistry, and we found that all were present in spiral ganglion neurons, three of which were neuron-specific (Ca(V)1.3, Ca(V)2.2, and Ca(V)3.3). Further characterization of neuron-specific α-subunits showed that Ca(V)1.3 and Ca(V)3.3 were tonotopically-distributed, whereas Ca(V)2.2 was uniformly distributed in apical and basal neurons. Multiple VGCC α-subunits were also immunolocalized to Schwann cells, having distinct intracellular localizations, and, significantly, appearing to distinguish putative compact (Ca(V)2.3, Ca(V)3.1) from loose (Ca(V)1.2) myelin. Electrophysiological evaluation of spiral ganglion neurons in the presence of TEA revealed Ca(2+) plateau potentials with slopes that varied proportionately with the cochlear region from which neurons were isolated. Because afterhyperpolarizations were minimal or absent under these conditions, we hypothesize that differential density and/or kinetics of one or more of the VGCC α-subunits could account for observed tonotopic differences. These experiments have set the stage for defining the clear multiplicity of functional control in neurons and Schwann cells of the spiral ganglion.
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Dror AA, Avraham KB. Hearing Impairment: A Panoply of Genes and Functions. Neuron 2010; 68:293-308. [DOI: 10.1016/j.neuron.2010.10.011] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2010] [Indexed: 12/13/2022]
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Ogita H, Nakagawa T, Sakamoto T, Inaoka T, Ito J. Transplantation of bone marrow-derived neurospheres into guinea pig cochlea. Laryngoscope 2010; 120:576-81. [DOI: 10.1002/lary.20776] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Hearing Loss and a Cell-Based Replacement Therapy. Otol Neurotol 2010. [DOI: 10.1097/mao.0b013e3181b76b89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
This study examined the potential of induced pluripotent stem (iPS) cells for use as a source of transplants for the restoration of auditory spiral ganglion neurons. We monitored neurite outgrowth from iPS cell-derived neural progenitors toward cochlear hair cells ex vivo, and followed their survival and fates after transplantation into mouse cochleae in vivo. Neurons derived from iPS cells projected neurites toward cochlear hair cells. The settlement of iPS cell-derived neurons was observed 1 week after transplantation into the cochlea. Some transplants expressed vesicular glutamate transporter 1, which is a marker for glutamatergic neurons. These findings indicate that iPS cells can be used as a source of transplants for the regeneration of spiral ganglion neurons.
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Abstract
HYPOTHESIS Cell replacement therapy in the inner ear will contribute to the functional recovery of hearing loss. BACKGROUND Cell replacement therapy is a potentially powerful approach to replace degenerated or severely damaged spiral ganglion neurons. This study aimed at stimulating the neurite outgrowth of the implanted neurons and enhancing the potential therapeutic of inner ear cell implants. METHODS Chronic electrical stimulation (CES) and exogenous neurotrophic growth factor (NGF) were applied to 46 guinea pigs transplanted with embryonic dorsal root ganglion (DRG) neurons 4 days postdeafening. The animals were evaluated with the electrically evoked auditory brainstem responses (EABRs) at experimental Days 7, 11, 17, 24, and 31. The animals were euthanized at Day 31, and the inner ears were dissected for immunohistochemistry investigation. RESULTS Implanted DRG cells, identified by enhanced green fluorescent protein fluorescence and a neuronal marker, were found close to Rosenthal canal in the adult inner ear for up to 4 weeks after transplantation. Extensive neurite projections clearly, greater than in nontreated animals, were observed to penetrate the bony modiolus and reach the spiral ganglion region in animals supplied with CES and/or NGF. There was, however, no significant difference in the thresholds of EABRs between DRG-transplanted animals supplied with CES and/or NGF and DRG-transplanted animals without CES or NGF supplement. CONCLUSION The results suggest that CES and/or NGF can stimulate neurite outgrowth from implanted neurons, although based on EABR measurement, these interventions did not induce functional connections to the central auditory pathway. Additional time or novel approaches may enhance functional responsiveness of implanted cells in the adult cochlea.
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Glavaski-Joksimovic A, Thonabulsombat C, Wendt M, Eriksson M, Ma H, Olivius P. Morphological differentiation of tau–green fluorescent protein embryonic stem cells into neurons after co-culture with auditory brain stem slices. Neuroscience 2009; 162:472-81. [DOI: 10.1016/j.neuroscience.2009.04.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2009] [Revised: 04/12/2009] [Accepted: 04/28/2009] [Indexed: 01/29/2023]
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Improve clinical outcomes for cochlear implant recipients by mimicing the viable cochlear environment to induce neural stem cells to differentiate into auditory neurons. Otol Neurotol 2009; 31:178-9; author reply 179-80. [PMID: 19574941 DOI: 10.1097/mao.0b013e3181b0fd76] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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28
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Sekiya T, Canlon B, Viberg A, Matsumoto M, Kojima K, Ono K, Yoshida A, Kikkawa YS, Nakagawa T, Ito J. Selective vulnerability of adult cochlear nucleus neurons to de-afferentation by mechanical compression. Exp Neurol 2009; 218:117-23. [PMID: 19393647 DOI: 10.1016/j.expneurol.2009.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 04/15/2009] [Indexed: 12/22/2022]
Abstract
It is well established that the cochlear nucleus (CN) of developing species is susceptible to loss of synaptic connections from the auditory periphery. Less information is known about how de-afferentation affects the adult auditory system. We investigated the effects of de-afferentation to the adult CN by mechanical compression. This experimental model is quantifiable and highly reproducible. Five weeks after mechanical compression to the axons of the auditory neurons, the total number of neurons in the CN was evaluated using un-biased stereological methods. A region-specific degeneration of neurons in the dorsal cochlear nucleus (DCN) and posteroventral cochlear nucleus (PVCN) by 50% was found. Degeneration of neurons in the anteroventral cochlear nucleus (AVCN) was not found. An imbalance between excitatory and inhibitory synaptic transmission after de-afferentation may have played a crucial role in the development of neuronal cell demise in the CN. The occurrence of a region-specific loss of adult CN neurons illustrates the importance of evaluating all regions of the CN to investigate the effects of de-afferentation. Thus, this experimental model may be promising to obtain not only the basic knowledge on auditory nerve/CN degeneration but also the information relevant to the application of cochlear or auditory brainstem implants.
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Affiliation(s)
- Tetsuji Sekiya
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Sakyou-ku, Kyoto 606-8507, Japan.
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Richardson RT, Wise AK, Andrew JK, O'Leary SJ. Novel drug delivery systems for inner ear protection and regeneration after hearing loss. Expert Opin Drug Deliv 2009; 5:1059-76. [PMID: 18817513 DOI: 10.1517/17425247.5.10.1059] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND A cochlear implant, the only current treatment for restoring auditory perception after severe or profound sensorineural hearing loss (SNHL), works by electrically stimulating spiral ganglion neurons (SGNs). However, gradual degeneration of SGNs associated with SNHL can compromise the efficacy of the device. OBJECTIVE To review novel drug delivery systems for preserving and/or regenerating sensory cells in the cochlea after SNHL. METHODS The effectiveness of traditional cochlear drug delivery systems is compared to newer techniques such as cell, polymer and gene transfer technologies. Special requirements for local drug delivery to the cochlea are discussed, such as protecting residual hearing and site-specific drug delivery for cell preservation and regeneration. RESULTS/CONCLUSIONS Drug delivery systems with the potential for immediate clinical translation, as well as those that will contribute to the future of hearing preservation or cochlear cellular regeneration, are identified.
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Affiliation(s)
- Rachael T Richardson
- Bionic Ear Institute, 384 Albert Street, East Melbourne, Victoria 3002, Australia.
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Backhouse S, Coleman B, Shepherd R. Surgical access to the mammalian cochlea for cell-based therapies. Exp Neurol 2008; 214:193-200. [PMID: 18773894 PMCID: PMC2630853 DOI: 10.1016/j.expneurol.2008.08.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 12/17/2022]
Abstract
Cochlear implants are dependent on functionally viable spiral ganglion neurons (SGNs) - the primary auditory neurons of the inner ear. Cell-based therapies are being used experimentally in an attempt to rescue SGNs from deafness-induced degeneration or to generate new neurons. The success of these therapies will be dependent on the development of surgical techniques designed to ensure precise cell placement while minimizing surgical trauma, adverse tissue reaction and cell dispersal. Using 24 normal adult guinea pigs we assessed three surgical procedures for cell delivery into the cochlea: (i) a cochleostomy into the scala tympani (ST); (ii) direct access to Rosenthal's canal - the site of the SGN soma - via a localized fracture of the osseous spiral lamina (RC); and (iii) direct access to the auditory nerve via a translabyrinthine surgical approach (TL). Half the cohort had surgery alone while the other half had surgery combined with the delivery of biocompatible microspheres designed to model implanted cells. Following a four week survival period the inflammatory response and SGN survival were measured for each cohort and the location of microspheres were determined. We observed a wide variability across the three surgical approaches examined, including the extent of the inflammatory tissue response (TL>>RC> or =ST) and the survival of SGNs (ST>RC>>TL). Importantly, microspheres were effectively retained at the implant site after all three surgical approaches. Direct access to Rosenthal's canal offered the most promising surgical approach to the SGNs, although the technique must be further refined to reduce the localized trauma associated with the procedure.
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Affiliation(s)
- Steven Backhouse
- The Bionic Ear Institute, 384 Albert Street, East Melbourne, Victoria 3002, Australia
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Hendricks JL, Chikar JA, Crumling MA, Raphael Y, Martin DC. Localized cell and drug delivery for auditory prostheses. Hear Res 2008; 242:117-31. [PMID: 18573323 DOI: 10.1016/j.heares.2008.06.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 05/09/2008] [Accepted: 06/02/2008] [Indexed: 12/20/2022]
Abstract
Localized cell and drug delivery to the cochlea and central auditory pathway can improve the safety and performance of implanted auditory prostheses (APs). While generally successful, these devices have a number of limitations and adverse effects including limited tonal and dynamic ranges, channel interactions, unwanted stimulation of non-auditory nerves, immune rejection, and infections including meningitis. Many of these limitations are associated with the tissue reactions to implanted auditory prosthetic devices and the gradual degeneration of the auditory system following deafness. Strategies to reduce the insertion trauma, degeneration of target neurons, fibrous and bony tissue encapsulation, and immune activation can improve the viability of tissue required for AP function as well as improve the resolution of stimulation for reduced channel interaction and improved place-pitch and level discrimination. Many pharmaceutical compounds have been identified that promote the viability of auditory tissue and prevent inflammation and infection. Cell delivery and gene therapy have provided promising results for treating hearing loss and reversing degeneration. Currently, many clinical and experimental methods can produce extremely localized and sustained drug delivery to address AP limitations. These methods provide better control over drug concentrations while eliminating the adverse effects of systemic delivery. Many of these drug delivery techniques can be integrated into modern auditory prosthetic devices to optimize the tissue response to the implanted device and reduce the risk of infection or rejection. Together, these methods and pharmaceutical agents can be used to optimize the tissue-device interface for improved AP safety and effectiveness.
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Affiliation(s)
- Jeffrey L Hendricks
- Department of Biomedical Engineering, The University of Michigan, 1107 Gerstacker Building, 2200 Bonisteel Boulevard, Ann Arbor, MI 48109-2099, USA.
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Lang H, Schulte BA, Goddard JC, Hedrick M, Schulte JB, Wei L, Schmiedt RA. Transplantation of mouse embryonic stem cells into the cochlea of an auditory-neuropathy animal model: effects of timing after injury. J Assoc Res Otolaryngol 2008; 9:225-40. [PMID: 18449604 DOI: 10.1007/s10162-008-0119-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Accepted: 03/06/2008] [Indexed: 12/18/2022] Open
Abstract
Application of ouabain to the round window membrane of the gerbil selectively induces the death of most spiral ganglion neurons and thus provides an excellent model for investigating the survival and differentiation of embryonic stem cells (ESCs) introduced into the inner ear. In this study, mouse ESCs were pretreated with a neural-induction protocol and transplanted into Rosenthal's canal (RC), perilymph, or endolymph of Mongolian gerbils either 1-3 days (early post-injury transplant group) or 7 days or longer (late post-injury transplant group) after ouabain injury. Overall, ESC survival in RC and perilymphatic spaces was significantly greater in the early post-injury microenvironment as compared to the later post-injury condition. Viable clusters of ESCs within RC and perilymphatic spaces appeared to be associated with neovascularization in the early post-injury group. A small number of ESCs transplanted within RC stained for mature neuronal or glial cell markers. ESCs introduced into perilymph survived in several locations, but most differentiated into glia-like cells. ESCs transplanted into endolymph survived poorly if at all. These experiments demonstrate that there is an optimal time window for engraftment and survival of ESCs that occurs in the early post-injury period.
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Affiliation(s)
- Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, 165 Ashley Avenue, P.O. Box 250908, Charleston, SC 29425, USA.
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