Учебники / Auditory Trauma, Protection, and Repair Fay 2008

development, in murine mesenchymal bone marrow stem cells, increases the expression of hair cell markers in vitro (Jeon et al. 2006), raising the question of whether autologous grafts of modified bone marrow stem cells are capable of replacing lost hair cells in vivo.

Embryonic stem cells are the most powerful stem cell type because these cells can give rise to all cell types, even a complete animal, a feature that is widely used to generate knockout mice. Stepwise coaxing of murine embryonic stem cells into cells with features of inner ear progenitors has shown that it is possible to use these embryonic stem cell–derived progenitors to generate hair cell marker–positive cells in vitro and in vivo, after grafting, into embryonic chicken otocysts (Li et al. 2003b). Human embryonic stem cells have been widely proposed as a source for replacement cell types. The generation of human hair cells from embryonic stem cells will certainly be an important milestone toward future therapeutic applications.

Despite the active research in this area, the functional replacement of lost hair cells with stem cell–derived cells still faces many challenges and it is difficult to predict the future development of specific avenues for treatment (Table 11.1). Nevertheless, the field of regenerative medicine and stem cell therapy is rapidly evolving and it is certain that insights gained from other organ systems will be applied to the inner ear whenever feasible. Ultimately, a perfect experiment should lead to substantial and sustained functional improvement of hearing in an animal model, which would be the only acceptable basis for development of future human therapy.

5. The Future

5.1 Multiple Starting Points

Ten years ago, the main focus of cochlear hair cell regeneration research was to identify the growth factors that were capable of inducing hair cell regeneration in the damaged organ of Corti. Since then, the repertoire of tools and technology has increased considerably. For example, researchers are now able to manipulate gene expression and to convert existing cells into hair cells via viral infection of the damaged organ of Corti with an expression vector for Atoh1. It is now common knowledge that knocking out cell cycle inhibitor genes, which are normally expressed in the mature organ of Corti, leads to mitotic cell production. A logic amalgamation of this particular application would be to combine a short suppression of cell cycle inhibitors with a subsequent and transient expression of Atoh1 via local infection with a gene therapy virus or other vehicles, transfection reagents, or even nanoparticles.

Likewise, highly efficient but transient transfection of bone marrow or other stem cell–derived cells with an Atoh1 expression vector before grafting may increase the chance of proper integration and differentiation of replacement hair cells in the damaged organ of Corti. Progenitor cells that can be grafted autologously or cells that do not generate an immune response are probably

334 S. Heller and Y. Raphael

good choices, but whether, for example, bone marrow–derived stem cells are indeed capable of engendering massive cochlear hair cell replacement needs to be determined.

Inner ear progenitors, derived from embryonic stem cells, may be able to serve as a unique tool to test growth factors or drug candidates for their ability to stimulate hair cell differentiation. Compounds identified in such a stem cell– based assay could be tested for efficacy to regenerate damaged human hair cells. Human embryonic stem cells are probably the most promising cell type that has not been explored in detail for its capacity to generate hair cells. It is already obvious that existing human embryonic stem cell lines need slightly different protocols than mouse embryonic stem cells to be converted into inner ear progenitors (Rivolta et al. 2006). Nevertheless, it is only a matter of time until the first stem cell–derived human hair cells will be generated either from embryonic stem cells or other stem cells (e.g., adult inner ear stem cells).

5.2 Science Fiction

It is understandable that the various types of hearing loss will require different therapeutic initiation points. For example, it will not be sufficient to stimulate hair cell regeneration in a patient with an underlying genetic defect that causes hair cell loss either directly or indirectly. Potential treatment scenarios for these cases could be the introduction of the wild-type version of the mutated gene in combination with stimulants of hair cell regeneration or stem cell–based transplantation therapy with cells that do not carry the mutation. Complex conditions such as connexin mutations may be treatable with a combination of gene therapy to restore the defective gap junction apparatus in the supporting cells with hair cell regeneration using stem cells.

Hair cell loss in the aging cochlea is a societal challenge. As long as the physiological effects of aging on the cochlea are not fully understood, no longterm regenerative solution for lost hair cells will be readily forthcoming unless a way is found to replenish lost hair cells constantly or to generate highly robust replacement hair cells. It is not inconceivable, however, that transgenic activation of antiapoptotic mechanisms will provide future “designer hair cells” with natural resistance to daily insults. Only time will tell whether the thoughts and speculations introduced in this paragraph are valid solutions for the treatment of hearing loss. Research and proof-of-principle experiments should be done using a variety of approaches to provide adequate choices for designs that may be selected for clinical trials aimed to cure hearing loss.

Acknowledgment. The research of Dr. Raphael has been supported by The R. Jamison and Betty Williams Professorship; Berte and Alan Hirschfield; the CHD, DRF, NOHR, and RNID; and several NIH NIDCD grants. The research of Dr. Heller has been supported by the DRF, the March of Dimes, NOHR, the McKnight Foundation, and several NIH-NIDCD grants. We thank Chris Gralapp for help with Fig. 11.1.

References

Adler HJ, Raphael Y (1996) New hair cells arise from supporting cell conversion in the acoustically damaged chick inner ear [published erratum appears in Neurosci Lett 205:17–20.

Adler HJ, Poje CP, Saunders JC (1993) Recovery of auditory function and structure in the chick after two intense pure tone exposures. Hear Res 71:214–224.

Avraham KB, Raphael Y (2003) Prospects for gene therapy in hearing loss. J Basic Clin Physiol Pharmacol 14:77–83.

Barald KF, Kelley MW (2004) From placode to polarization: new tunes in inner ear development. Development 131:4119–4130.

Bermingham NA, Hassan BA, Price SD, Vollrath MA, Ben-Arie N, Eatock RA, Bellen HJ, Lysakowski A, Zoghbi HY (1999) Math1: an essential gene for the generation of inner ear hair cells. Science 284:1837–1841.

Bermingham-McDonogh O, Stone JS, Reh TA, Rubel EW (2001) FGFR3 expression during development and regeneration of the chick inner ear sensory epithelia. Dev Biol 238:247–259.

Chen P, Segil N (1999) p27(Kip1) links cell proliferation to morphogenesis in the developing organ of Corti. Development 126:1581–1590.

Chen P, Johnson JE, Zoghbi HY, Segil N (2002) The role of Math1 in inner ear development: uncoupling the establishment of the sensory primordium from hair cell fate determination. Development 129: 2495–2505.

Chen P, Zindy F, Abdala C, Liu F, Li X, Roussel MF, Segil N (2003) Progressive hearing loss in mice lacking the cyclin-dependent kinase inhibitor Ink4d. Nat Cell Biol 5:422–426.

Chen X, Frisina RD, Bowers WJ, Frisina DR, Federoff HJ (2001) HSV amplicon-mediated neurotrophin-3 expression protects murine spiral ganglion neurons from cisplatininduced damage. Mol Ther 3:958–963.

Corwin JT (1981) Postembryonic production and aging in inner ear hair cells in sharks. J Comp Neurol 201:541–553.

Corwin JT (1983) Postembryonic growth of the macula neglecta auditory detector in the ray, Raja clavata: continual increases in hair cell number, neural convergence, and physiological sensitivity. J Comp Neurol 217:345–356.

Corwin JT (1985) Perpetual production of hair cells and maturational changes in hair cell ultrastructure accompany postembryonic growth in an amphibian ear. Proc Natl Acad Sci USA 82:3911–3915.

Corwin JT, Cotanche DA (1988) Regeneration of sensory hair cells after acoustic trauma. Science 240:1772–1774.

Cotanche DA, Lee KH, Stone JS, Picard DA (1994) Hair cell regeneration in the bird cochlea following noise damage or ototoxic drug damage. Anat Embryol 189:1–18.

Cotanche DA, Messana EP, Ofsie MS (1995) Migration of hyaline cells into the chick basilar papilla during severe noise damage. Hear Res 91:148–159.

Crumling MA, Raphael Y (2006) Manipulating gene expression in the mature inner ear. Brain Res 1091:265–269.

Dooling RJ, Ryals BM, Manabe K (1997) Recovery of hearing and vocal behavior after hair-cell regeneration. Proc Natl Acad Sci USA 94:14206–14210.

Fekete DM (2000) Making sense of making hair cells. Trends Neurosci 23:386.

Fekete DM, Wu DK (2002) Revisiting cell fate specification in the inner ear. Curr Opin Neurobiol 12:35–42.

336 S. Heller and Y. Raphael

Forge A, Li L, Corwin JT, Nevill G (1993) Ultrastructural evidence for hair cell regeneration in the mammalian inner ear. Science 259:1616–1619.

Fritzsch B, Pauley S, Beisel KW (2006) Cells, molecules and morphogenesis: the making of the vertebrate ear. Brain Res 1091:151–171.

Girod DA, Duckert LG, Rubel EW (1989) Possible precursors of regenerated hair cells in the avian cochlea following acoustic trauma. Hear Res 42:175–194.

Hashino E, Salvi RJ (1993) Changing spatial patterns of DNA replication in the noisedamaged chick cochlea. J Cell Sci 105:23–31.

Hawkins JE Jr, Preston RE (1975) Vestibular ototoxicity. In: Naunton RF (ed) The Vestibular System. New York: Academic Press, pp. 321–349.

Hawkins RD, Bashiardes S, Helms CA, Hu L, Saccone NL, Warchol ME, Lovett M (2003) Gene expression differences in quiescent versus regenerating hair cells of avian sensory epithelia: implications for human hearing and balance disorders. Hum Mol Genet 12:1261–1272.

Hawkins RD, Helms CA, Winston JB, Warchol ME, Lovett M (2006) Applying genomics to the avian inner ear: development of subtractive cDNA resources for exploring sensory function and hair cell regeneration. Genomics 87:801–808.

Ishimoto S, Kawamoto K, Kanzaki S, Raphael Y (2002) Gene transfer into supporting cells of the organ of Corti. Hear Res 173:187–197.

Izumikawa M, Minoda R, Kawamoto K, Abrashkin KA, Swiderski DL, Dolan DF, Brough DE, Raphael Y (2005) Auditory hair cell replacement and hearing improvement by Atoh1 gene therapy in deaf mammals. Nat Med 11:271–276.

Jeon SJ, Oshima K, Heller S, Edge AS (2006) Bone marrow mesenchymal stem cells are progenitors in vitro for inner ear hair cells. Mol Cell Neurosci.

Kanzaki S, Beyer LA, Swiderski DL, Izumikawa M, Stover¨ T, Kawamoto K, Raphael Y (2006) p27(Kip1) deficiency causes organ of Corti pathology and hearing loss. Hear Res 214:28–36.

Kawamoto K, Yagi M, Stover¨ T, Kanzaki S, Raphael Y (2003a) Hearing and hair cells are protected by adenoviral gene therapy with TGF-beta1 and GDNF. Mol Ther 7:484–492.

Kawamoto K, Ishimoto S, Minoda R, Brough DE, Raphael Y (2003b) Math1 gene transfer generates new cochlear hair cells in mature guinea pigs in vivo. J Neurosci 23:4395–4400.

Kelley MW (2003) Cell adhesion molecules during inner ear and hair cell development, including notch and its ligands. Curr Top Dev Biol 57:321–356.

Kondo T, Johnson SA, Yoder MC, Romand R, Hashino E (2005) Sonic hedgehog and retinoic acid synergistically promote sensory fate specification from bone marrowderived pluripotent stem cells. Proc Natl Acad Sci USA 102:4789–4794.

Li H, Liu H, Heller S (2003a) Pluripotent stem cells from the adult mouse inner ear. Nat Med 9:1293–1299.

Li H, Roblin G, Liu H, Heller S (2003b) Generation of hair cells by stepwise differentiation of embryonic stem cells. Proc Natl Acad Sci USA 100:13495–13500.

Lindeman HH (1969) Regional differences in sensitivity of the vestibular sensory epithelia to ototoxic antibiotics. Acta Otolaryngol 67:177–189.

Lohmann DR, Gallie BL (2004) Retinoblastoma: revisiting the model prototype of inherited cancer. Am J Med Genet C Semin Med Genet 129:23–28.

Lopez I, Honrubia V, Lee SC, Li G, Beykirch K (1998) Hair cell recovery in the chinchilla crista ampullaris after gentamicin treatment: a quantitative approach. Otolaryngol Head Neck Surg 119:255–262.

Lowenheim¨ H, Furness DN, Kil J, Zinn C, Gultig K, Fero ML, Frost D, Gummer AW, Roberts JM, Rubel EW, Hackney CM, Zenner HP (1999) Gene disruption of p27(Kip1) allows cell proliferation in the postnatal and adult organ of corti. Proc Natl Acad Sci USA 96:4084–4088.

Malgrange B, Belachew S, Thiry M, Nguyen L, Rogister B, Alvarez ML, Rigo JM, Van De Water TR, Moonen G, Lefebvre PP (2002) Proliferative generation of mammalian auditory hair cells in culture. Mech Dev 112:79–88.

Marean GC, Cunningham D, Burt JM, Beecher MD, Rubel EW (1995) Regenerated hair cells in the European starling: are they more resistant to kanamycin ototoxicity than original hair cells? Hear Res 82:267–276.

Matsui JI, Gale JE, Warchol ME (2004) Critical signaling events during the aminoglycoside-induced death of sensory hair cells in vitro. J Neurobiol 61:250–266.

McKay R (1997) Stem cells in the central nervous system. Science 276:66–71. Meiteles LZ, Raphael Y (1994) Scar formation in the vestibular sensory epithelium after

aminoglycoside toxicity. Hear Res 79:26–38.

Montcouquiol M, Kelley MW (2003) Planar and vertical signals control cellular differentiation and patterning in the mammalian cochlea. J Neurosci 23:9469–9478.

Naito Y, Nakamura T, Nakagawa T, Iguchi F, Endo T, Fujino K, Kim TS, Hiratsuka Y, Tamura T, Kanemaru S, Shimizu Y, Ito J (2004) Transplantation of bone marrow stromal cells into the cochlea of chinchillas. NeuroReport 15:1–4.

Niemiec AJ, Raphael Y, Moody DB (1994) Return of auditory function following structural regeneration after acoustic trauma: behavioral measures from quail. Hear Res 79:1–16.

Oshima, K, Corrales, CE, Grimm, C, Senn, P, Martinez Monedero, R, Geleoc, GS, Edge, A, Holt, JC, and Heller, S (2007). Differential distribution of stem cells in the auditory and vestibular organs of the inner ear. J Assoc Res Otolaryngol 8: 18–31.

Patel NP, Mhatre AN, Lalwani AK (2004) Biological therapy for the inner ear. Expert Opin Biol Ther 4:1811–1819.

Raphael Y (1992) Evidence for supporting cell mitosis in response to acoustic trauma in the avian inner ear. J Neurocytol 21:663–671.

Raphael Y (1993) Reorganization of the chick basilar papilla after acoustic trauma. J Comp Neurol 330:521–532.

Raphael Y, Adler HJ, Wang Y, Finger PA (1994) Cell cycle of transdifferentiating supporting cells in the basilar papilla. Hear Res 80:53–63.

Rask-Andersen H, Bostrom M, Gerdin B, Kinnefors A, Nyberg G, Engstrand T, Miller JM, Lindholm D (2005) Regeneration of human auditory nerve. In vitro/in video demonstration of neural progenitor cells in adult human and guinea pig spiral ganglion. Hear Res 203:180–191.

Rivolta M, Li H, Heller S (2006) Generation of inner ear cell types from embryonic stem cells. In: Turksen K (ed) Embryonic Stem Cell Protocols, Volume II: Differentiation, Models. Totowa, NJ: Humana Press, pp. 71–92.

Roberson DW, Kreig CS, Rubel EW (1996) Light microscopic evidence that direct transdifferentiation gives rise to new hair cells in regenerating avian auditory epithelium. Audit Neurosci 2:195–205.

Ryals BM, Rubel EW (1988) Hair cell regeneration after acoustic trauma in adult Coturnix quail. Science 240:1774–1776.

Sage C, Huang M, Karimi K, Gutierrez G, Vollrath MA, Zhang DS, Garcia-Anoveros J, Hinds PW, Corwin JT, Corey DP, Chen ZY (2005) Proliferation of functional hair cells in vivo in the absence of the retinoblastoma protein. Science 307:1114–1118.

338 S. Heller and Y. Raphael

Sen A, Kallos MS, Behie LA (2002) Passaging protocols for mammalian neural stem cells in suspension bioreactors. Biotechnol Prog 18:337–345.

Sherr CJ, Roberts JM (1999) CDK inhibitors: positive and negative regulators of G1-phase progression. Genes Dev 13:1501–1512.

Shou J, Zheng JL, Gao WQ (2003) Robust generation of new hair cells in the mature mammalian inner ear by adenoviral expression of Hath1. Mol Cell Neurosci 23: 169–179.

Staecker H, Gabaizadeh R, Federoff H, Van De Water TR (1998) Brain-derived neurotrophic factor gene therapy prevents spiral ganglion degeneration after hair cell loss. Otolaryngol Head Neck Surg 119:7–13.

Stone JS, Cotanche DA (1994) Identification of the timing of S phase and the patterns of cell proliferation during hair cell regeneration in the chick cochlea. J Comp Neurol 341:50–67.

Stone JS, Shang JL, Tomarev S (2004) cProx1 immunoreactivity distinguishes progenitor cells and predicts hair cell fate during avian hair cell regeneration. Dev Dyn 230: 597–614.

Stover¨ T, Yagi M, Raphael Y (1999) Cochlear gene transfer: round window versus cochleostomy inoculation. Hear Res 136:124–130.

Svendsen CN, ter Borg MG, Armstrong RJ, Rosser AE, Chandran S, Ostenfeld T, Caldwell MA (1998) A new method for the rapid and long term growth of human neural precursor cells. J Neurosci Methods 85:141–152.

Tateya I, Nakagawa T, Iguchi F, Kim TS, Endo T, Yamada S, Kageyama R, Naito Y, Ito J (2003) Fate of neural stem cells grafted into injured inner ears of mice. NeuroReport 14:1677–1681.

Torres M, Giraldez F (1998) The development of the vertebrate inner ear. Mech Dev 71:5–21.

Tsue TT, Oesterle EC, Rubel EW (1994) Hair cell regeneration in the inner ear. Otolaryngol Head Neck Surg 111:281–301.

Tucci DL, Rubel EW (1990) Physiologic status of regenerated hair cells in the avian inner ear following aminoglycoside ototoxicity. Otolaryngol Head Neck Surg 103:443–450.

Warchol ME (2002) Cell density and N-cadherin interactions regulate cell proliferation in the sensory epithelia of the inner ear. J Neurosci 22:2607–2616.

Warchol ME, Lambert PR, Goldstein BJ, Forge A, Corwin JT (1993) Regenerative proliferation in inner ear sensory epithelia from adult guinea pigs and humans. Science 259:1619–1622.

Wilkins HR, Presson JC, Popper AN, Ryals BM, Dooling RJ (2001) Hair cell death in a hearing-deficient canary. J Assoc Res Otolaryngol 2:79–86.

Witte MC, Montcouquiol M, Corwin JT (2001) Regeneration in avian hair cell epithelia: identification of intracellular signals required for S-phase entry. Eur J Neurosci 14: 829–838.

Woods C, Montcouquiol M, Kelley MW (2004) Math1 regulates development of the sensory epithelium in the mammalian cochlea. Nat Neurosci 7:1310–1318.

Yagi M, Magal E, Sheng Z, Ang KA, Raphael Y (1999) Hair cell protection from aminoglycoside ototoxicity by adenovirus-mediated overexpression of glial cell linederived neurotrophic factor. Hum Gene Ther 10:813–823.

Zheng JL, Gao WQ (2000) Overexpression of Math1 induces robust production of extra hair cells in postnatal rat inner ears. Nat Neurosci 3:580–586.

Zine A (2003) Molecular mechanisms that regulate auditory hair-cell differentiation in the mammalian cochlea. Mol Neurobiol 27:223–238.