Hair Cell Regeneration Update
Editor: Hair cell regeneration and the related stem cell research
offer what is probably the best hope for hearing restoration in the next
few years. A reader who follows these developments just sent me four
stories, each of which discusses promising medical discoveries. Two of
the stories are late-breaking news and two are from earlier this summer.
Here are a couple of paragraphs from each story and a link to the full
article.
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Article 1: New Inner Ear Stem Cells Discovered - http://tinyurl.com/mag6
BOSTON, Sept. 3 (AScribe Newswire) -- Hearing loss and vestibular
disorders often have debilitating effects on affected individuals,
ranging in severity from modest difficulty with speech comprehension to
profound deafness, tinnitus or dizziness. Hearing loss is the most
prevalent chronic disease of the elderly, affecting more than one third
of people over 65 years of age. In most cases, hearing loss is caused by
degeneration of the inner ear's sensory receptor cells or "hair
cells."
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, has discovered a new population of stem cells that
reside in the inner ear of adult mice. Huawei Li, Ph.D., a postdoctoral
associate of the laboratory, found that these cells give rise to new
hair cells in the culture dish, as well as after transplantation into
embryonic inner ears of laboratory animals. The combination of these two
discoveries could eventually lead to new hope for some people who suffer
from hearing loss.
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Article 2: Chicken Embryo Research Tunes Into Inner Ear - http://www.sciencedaily.com/releases/2003/09/030903074509.htm
WEST LAFAYETTE, Ind. - Purdue University biologists have learned how
to control the development of stem cells in the inner ears of embryonic
chickens, a discovery which could potentially improve the ability to
treat human diseases that cause deafness and vertigo.
By introducing new genes into the cell nuclei, researchers instructed
the embryonic cells to develop into different adult cells than they
would have ordinarily. Instead of forming the tiny hairs that the inner
ear uses to detect sound waves, the stem cells matured into tissue with
different kind of hairs - the sort used to keep balance. This ability to
guide the choice of cell types could expand researchers' knowledge of
the inner ear and its disorders.
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Article 3: Gene therapy grows new auditory hair cells in mammals -
http://www.eurekalert.org/pub_releases/2003-05/uomh-gtg052703.php
ANN ARBOR, MI - University of Michigan scientists have used gene
therapy to grow new auditory hair cells in adult guinea pigs - a
discovery that could lead to new treatments for human deafness and
age-related hearing loss.
Healthy hair cells are vital to the ability to hear, but aging,
infection, certain medications and exposure to loud noises can damage or
destroy hair cells causing sensorineural hearing loss - a condition
affecting over 30 million Americans. Since the discovery, in the late
1980s, that birds can spontaneously regenerate damaged hair cells,
scientists have been trying to find a way to induce the replacement of
lost hair cells in mammals.
U-M scientists have now accomplished this goal by inserting a gene
called Math1 into non-sensory epithelial cells lining the inner ear.
Results from the study will be published in the June 1 issue of the
Journal of Neuroscience.
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Article 4: GenVec Announces Early Research Efforts for Inner Ear
Disorders -
http://www.corporate-ir.net/ireye/ir_site.zhtml?ticker=GNVC
&script=410&layout=-6&item_id=418882
GAITHERSBURG, Md., Jun 4, 2003 /PRNewswire-FirstCall via COMTEX/ --
GenVec, Inc. (Nasdaq: GNVC), a biopharmaceutical company, today
announced promising early data on its research into possible treatments
for hearing loss and balance disorders. Proof-of-principle studies
conducted at Dr. Yehoash Raphael's laboratory at the University of
Michigan using the atonal homolog, MATH-1, and GenVec's proprietary
technology showed the generation of new hair cells in mature mammalian
inner ears, which could have the potential for treating hearing loss.
GenVec also has a research collaboration with Dr. Hinrich Staecker at
the University of Maryland, which is focused on balance disorders.
The human ear is responsible for hearing and balance. There are many
different medical conditions that result in hearing loss and problems
with balance. The most common reason is the absence of functional hair
cells in the inner ear. A hair cell has tiny "hair like"
projections that contain receptors that receive signals of sound and
motion. These signals are transmitted through nerves to the brain and
help a person hear and maintain balance. Regeneration of new hair cells
offers a possible new approach in the treatment of hearing loss and
balance dysfunction.
