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10/28/2003 Archived Entry: "LISTEN UP AGAIN! cochlear hair cells can be generated by stepwise differentiation of embryonic stem (ES) cells"

The Scientist reports some very exciting findings: In the October 27 PNAS, Huawei Li and colleagues from Harvard Medical School show that cochlear hair cells can be generated by stepwise differentiation of embryonic stem (ES) cells (PNAS, DOI:10.1073/pnas.2334503100, October 27, 2003). ... some earlier references to Ear Nose Throat J. 1998 Apr;77(4):276, 280, 282-5 Mammalian auditory hair cell regeneration/repair and protection: a review and future directions. by Feghali JG, Lefebvre PP, Staecker H, Kopke R, Frenz DA, Malgrange B, Liu W, Moonen G, Ruben RJ, Van de Water TR. of the Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York, USA. (ABSTRACT: regeneration/repair and protection of auditory hair cells and auditory neurons is an exciting, rapidly evolving field. Simultaneous developments in the fields of otobiology and surgical otology have led to new and exciting possibilities in inner ear medicine and surgery; specifically, the treatment or prevention of a variety of types of hearing losses in the foreseeable future. .... It has been generally accepted that hearing loss resulting from hair cell damage is irreversible because the human ear has been considered to be incapable of regenerating or repairing these sensory elements following severe injury. An organ of Corti explant study has shown that it is possible to initiate the regeneration/repair of mammalian hair cells. In this study, ototoxin-damaged organ of Corti explants from juvenile rats were treated with a combination of retinoic acid (10-8M) and fetal calf serum (10%). TGF-alpha has been identified as a growth factor capable of evoking auditory hair cell regeneration/repair in ototoxin-damaged organ of Corti explants. ... Administration of growth factors to the inner ears of animals is now possible with the use of implanted catheters and miniature infusion pumps. These advances suggest that localized application of drugs to the human inner ear may be feasible.")

For some reason the PNAS reference doen't work (maybe its published in another journal like Nature or maybe its coming out later), but looking at Harvard's site; one finds the following statements "Stefan Heller and postdoctoral fellow Huawei Li were surprised at how easily pluripotent cells can be isolated from the mouse inner ear. These stem cells not only yield hair-like hair cells that may prove useful in restoring deafness, but when transplanted into chick embryos, can give rise to cells in all three germ layers." .... there's more .... "Regeneration of similar hair cells has been observed, however, in another part of the mammalian inner ear, a section of the vestibular organ called the utricle. This, plus the finding some 15 years ago that the avian equivalent of the organ of Corti can recover from total hair cell loss, suggests that promoting hair cell proliferation in the human inner ear may prove a viable treatment for hearing loss.". THIS IS TRULY AWESOME

In the meantime Massachusetts Eye and Ear Infirmary has an October 27 2003 Press Release on the matter that states: Generation of inner ear cells from stem cells may lead to new approaches to hearing loss and deafness: (Boston, Mass.) - ... A research team led by Stefan Heller, Ph.D., a principal investigator at the Massachusetts Eye and Ear Infirmary's Eaton-Peabody Laboratory and assistant professor, Department of Otology and Laryngology, Harvard Medical School, recently discovered a new population of stem cells that reside in the inner ear of adult mice. Heller's lab has taken this work one step further in a study outlined in the Proceedings of the National Academy of Sciences early edition that will publish online the week of Oct. 27-Oct. 31. .... Heller's laboratory has found a way to coax mouse embryonic stem cells to develop into inner ear precursor cells that ultimately have the ability to differentiate into the inner ear's sensory cells, hair cells. ... "Pilot cell transplantation experiments revealed that these embryonic stem cell-derived progenitors can integrate into developing vestibular and cochlear hair cell layers and that the transplanted cells express genes specific for hair cells," Heller said. "Using embryonic stem cells as the source for inner ear cell types has the advantage that we can generate large numbers of these cells. Larger numbers of material for research will expedite the development of cell transplantation techniques."..... "I think that these findings now open the door for novel approaches in the search for methods to replace lost hair cells, which is a major cause of deafness." ... We'll keep track and follow up.