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January 2001
As most of our readers probably know, most hearing loss is caused by
deterioration of the hair cells in the cochlea. The hair cells move in
response to acoustic energy entering the ear, and stimulate the auditory
nerve with information regarding the characteristics of the incoming
sound. Drugs, heredity, or loud noises can damage or destroy the hair
cells, resulting in hearing loss.
We have known for some time that some animals (including many birds)
can spontaneously regenerate damaged hair cells, but regeneration has
never been observed in mammals - until now. The August 26, 2000 Issue of
the British medical Journal Lancet reported successful regeneration of
hair cells in a postnatal rat cochlea by introducing a particular gene
(Math1) to the cochlea. Researcher Wei-Qiang Gao (Genentech, San
Francisco, CA,USA) points out, "It wasn't just a few hair cells--we
had several hundred, so it's robust production".
The next step in the investigation is to determine whether similar
techniques can regenerate hair cells in mature rats. Success in these
experiments would bode well for eventual hair cell regeneration in
humans.
Another possibility to replace damaged hair cells is transplantation.
Matthew Holley (University of Bristol, UK) and his colleagues have
developed an "ear in a test tube", in which they have
successfully grown mouse hair cells. Future advances may allow growth
and transplantation of human hair cells.
~~~~~~~~~~~~~~~~
August 2001
The House Ear Institute has been actively involved in the research on
hair cell regeneration. They are pursuing two complementary strategies
in hopes of understanding the regeneration process and how to induce it
in humans. Here's a link to an article describing their recent work.
http://www.hei.org/research/projects/cmb/haircellchall.htm
~~~~~~~~~~~~~~~~
October 2003
Editor: Here's more breaking news on hair cell regeneration. Sound
Pharmaceuticals has been issued a European patent for its hair cell
regeneration treatment. Note that this development is only part of the
required solution, and it doesn't mean that a treatment will be widely
available next week. But I think it is a big step towards viable hair
cell regeneration. Here's the press release.
~~~~~~~~~~~~~~~~~~~
Sound Pharmaceuticals, Inc. (SPI) announced that its patent
"Method for the treatment of diseases or disorders of the inner
ear" has issued in Europe, effective Oct. 1, 2003.
SPI has developed a novel strategy to stimulate auditory hair cell
regeneration using proprietary cell cycle inhibition technology.
Typically, auditory hair cells in mammals are not replaced when injured
or lost. This results in permanent and often progressive sensorineural
hearing a disease that affects over 30 million in the US. In non-mammals
like birds, hair cell regeneration occurs through the spontaneous
proliferation of the adjacent supporting cell. These newly proliferating
supporting cells can go on to become replacement hair cells. However in
mammals, auditory supporting cells do not proliferate or regenerate into
hair cells even in the presence of growth factors.
SPI identified that p27Kip1, a cyclin dependent kinase inhibitor,
prevents supporting cells from proliferating after embryogenesis.
Compounds developed by SPI to inhibit p27Kip1 have been shown to
stimulate supporting cell proliferation after drug or noise induced hair
cell loss. "We are the only group that has demonstrated the ability
to stimulate proliferative regeneration in the cochlea of mammals"
says Dr. Jonathan Kil, President & CEO. "It is anticipated that
this revolutionary technology will be critical in developing treatments
to restore hearing in humans."
Sound Pharmaceuticals, Inc. is a drug development company focused on
treating hearing loss. To date, Sound Pharmaceuticals' drug discovery
program has identified targets for the prevention of hearing loss and
for the improvement of hearing in individuals with hearing loss. For
more information please visit http://www.soundpharmaceuticals.com
~~~~~~~~~~~~~~~~~~~
October 2004
Editor: For people interested in hearing loss "cures", hair
cell regeneration is the current best bet. It appears that virtually all
animals except mammals regenerate hair cells on a routine basis. Dr.
Edwin W. Rubel and his colleagues are among the researchers on the
forefront of this exciting technology. "Hearing Review"
recently published an interview of Dr. Rubel along with a synopsis of
the research status. Here's one question and answer from the interview.
The complete article is available at:
http://www.hearingreview.com/Articles.ASP?articleid=H0410F01
~~~~~~~~~~~~~~~~~~~
Hearing Review: If hair cell regeneration is indeed possible, do you
think this science will ever progress to a point where there will be
full restoration of hair cells, or do you think that it's far more
likely we would see a partial restoration of hair cells in the inner
ear?
Rubel: In my opinion, it's not a question of if we will regenerate,
restore, or protect hair cells, it's a question of when. Because we now
know that it's possible, it's only a matter of time until we can apply
this science to humans. My best prediction is 10-20 years. I certainly
hope to see it in my lifetime.
With respect to the degree of hair cell regeneration or restoration,
my gut feeling is that it will all depend on what type of hearing loss a
person has to begin with. One possibility for regeneration are people
who have complete loss of hair cells due to some genetic anomaly,
ototoxins, aminoglycosides, etc. In these cases, hearing care
professionals may someday have a choice between recommending a cochlear
implant versus an approach for growing enough hair cells where hearing
aids could be used more effectively and provide much more acoustic
information to that patient. As another example, you might see a patient
who has a 50% loss of their outer hair cells. In this case, maybe we
will be able to stimulate the regrowth and replacement of these
"cochlear amplifier" cells.
~~~~~~~~~~~~~~~~~~~
November 2004
Editor: "The Scotsman" is reporting on research at
Sheffield University that may enable hearing restoration in the
foreseeable future. Here are excerpts from the story. For the complete
article, please point your browser to http://news.scotsman.com/uk.cfm?id=1346202004
~~~~~~~~~~~~~~~~~~~
SCIENTISTS hope that stem-cell research could lead to a cure for
deafness in as little as ten years.
Researchers from Sheffield University are using embryonic stem cells
in efforts to grow new cells in the inner ear.
Although in its early stages, the team from Sheffield University
hopes it could lead to a cure for deafness in ten to 15 years.
[snip]
Dr Rivolta added that his team hoped to undertake the first tests on
animals in two years. "It could then be possible to do human trials
in three to four years, but that would depend on the animal
trials."
~~~~~~~~~~~~~~~~~
June 2007
Here's a great article that explains the structure
and function of inner and outer hair cells and also looks at some of the
research into regrowing these cells. If you're interested in this topic,
it's very much worth the read!
Full Story
~~~~~~~~~~~~~~~~~
June 2007
Dr. Jeffrey Holt, associate professor of
neuroscience and otolaryngology at UVa, and his research team, including
Dr. Bradley Kesser, an assistant professor of otolaryngology, targeted a
gene known as KCNQ4, which causes genetic hearing loss in humans when
mutated. They engineered a correct form of the gene and created a gene
therapy delivery system that successfully transferred the KCNQ4 gene into
human hair cells harvested from the inner ears of patients with hearing
loss. "Our results show that gene therapy reagents are effective in human
inner ear tissue. Taken together with the results from another group of
scientists who showed that similar gene therapy compounds can produce new
hair cells and restore hearing function in guinea pigs suggest that the
future of gene therapy in the human inner ear is sound," Holt said.
Full
Story
~~~~~~~~~~~~~~~~~
September 2007
Woodstick, is the incredible annual event
sponsored by the Rotarians for Hearing Regeneration: A Rotarian Action
Group during which we: Attempt to break the Guinness World record by
assembling the largest number of drummers with drum sets playing one song
simultaneously (Woodstick currently holds the existing record of 533
drummers!) Raise money for worthwhile causes. Our featured cause is
Hearing Regeneration. Our goal is to raise 15 million dollars over the
next ten years for the Virginia Merrill Bloedel Hearing Research Center at
the University of Washington. Also, we will be raising money for the
homeless for Network Services, and funding around $10,000 worth of musical
instruments and equipment to local schools for school music programs.
Full Story
~~~~~~~~~~~~~~~~~
November 2007
Researchers at the University of Virginia have
developed a new method of growing inner-ear hair cells that will aid
research to help people regain their hearing. Dr. Jeffrey T. Corwin, a
professor of neuroscience at the UVa Health System, and Dr. Zhengqing Hu,
a neuroscience research assistant, have been growing cells from inner ears
of chicken embryos. They hope to extend that knowledge to re-grow the
inner-ear hair cells of humans. Mammals grow inner-ear hair cells only
before they are born, unlike amphibians and birds, which can re-grow
damaged or lost cells. These unique structures are lost over time as
mammals age, or if they contract certain infections or undergo trauma. The
loss of inner-ear hair cells results in hearing loss and balance
impairment. Hu and Corwin's process is able to grow chicken inner-ear hair
cells in a laboratory setting.
Full Story
~~~~~~~~~~~~~~~~~
November 2008
Iranian researchers managed to successfully
extract bone marrow stem cells from rodents and produce in vitro inner ear
hair cells. "In this two-year project, researchers cultured and produced
inner ear hair cells, a procedure which is not commonly performed in other
countries," research team-leader, Mohammad Farhadi told the Iranian
students news agency. Farhadi reported that injecting the resulted cells
into deaf mice has successfully tackled hearing loss in them.
Full Story
~~~~~~~~~~~~~~~~~
May 2009
Twenty years have passed since the discovery of
hair cell regeneration in birds (Corwin & Cotanche, 1988; Ryals & Rubel,
1988). The initial excitement caused by this discovery has been followed
by steady progress in understanding the fundamental mechanisms that
recently culminated in research evidence of hair cell regeneration in both
the auditory and vestibular portions of the mammalian inner ear (Kawamoto
et al., 2003; Izumikawa et al., 2005; Staecker et al., 2007). Clinical
audiologists are faced with the responsibility of translating these basic
science findings into potential patient application. They raise important
questions: When will hair cell regeneration be a reality for my patients?
What will be the measures of candidacy? What will the impact of hair cell
regeneration be in my patients who use or are candidates for hearing aids
or other amplification devices? Will hearing aids or cochlear implants
continue to be needed in the face of hair cell regeneration?
Full Story
~~~~~~~~~~~~~~~~~
June 2009
More than 20 years ago, Douglas Cotanche, PhD,
then at the Medical University of South Carolina and now affiliated with
Children's Hospital Boston, discovered that the hair cells within the
chick cochlea were capable of a "significant amount of recovery and
regeneration" following acoustic trauma.1 His unexpected discovery began a
cascade of research on the question of whether hair cells within the human
cochlea could someday achieve the same regenerative results. If and when
this happens, many of the causes of hearing loss in humans, from noise to
aging, can finally be resolved without the need for hearing aids or
cochlear implants. Although steady progress has been made in understanding
the mechanisms underlying hair cell regeneration, human subjects have yet
to participate in clinical trials concerned with regrowing hair cells.
Such trials may still be years away. Let's look at a sampling of the
research in 2008, which moves us ever closer to the goal of restoring
hearing in this most natural way.
Full Story
~~~~~~~~~~~~~~~~~
August 2009
For many people, loss of hearing is irreversible.
For scientists trying to figure out what can be done about that, one
answer may lie-or swim, actually-in freshwater aquariums. About one of
every 10 Americans suffers from hearing impairment, according to a survey
conducted by the Better Hearing Institute, a nonprofit advocacy group. By
far the most common cause of hearing loss is damage to the so-called hair
cells in the inner ear as a result of excessive noise, certain illnesses
and drugs, and simple aging. The problem is that once hair cells die,
humans (like other mammals) aren't able to grow new ones. In recent years,
a research team at the University of Washington in Seattle has been
working on finding a way to resolve that problem in experiments involving
the zebrafish, a common aquarium denizen. The zebrafish, like many aquatic
creatures, has clusters of hair cells running along the outside of its
body that help sense vibrations in the water, working in a similar way to
hair cells in the human inner ear. But unlike humans, zebrafish are able
to regenerate their damaged hair cells. Researchers hope their work can
unlock secrets to protect human hair cells from becoming damaged and to
stimulate the cells to regenerate.
Full Story
~~~~~~~~~~~~~~~~~
May 2011
Stefan Heller, Ph.D., is a professor of
otolaryngology and a professor of molecular and cellular biology at the
Stanford University School of Medicine.He is also the principle
investigator of Heller Lab in Stanford's Department of Otolaryngology.
Roughly a decade ago, Heller proposed that stem cells could be used to
create the specialized inner-ear hair cells that are critical for our
ability to hear. Unlike birds, fish, and amphibians,mammals cannot
regenerate hair cells, so once they are lost or damaged, the hearing loss
is permanent. Last May Heller reported in the journal Cell that he and his
team had successfully created mouse cells that not only resemble but also
behave like mouse inner-ear hair cells. In an interview with Hearing
Health, Heller reviewed the advances his lab has made since that
significant study.
Full Story
~~~~~~~~~~~~~~~~~
September 2011
Abstract: Sensory neural hearing loss and
vestibular dysfunction have become the most common forms of sensory
defects, affecting millions of people worldwide. Developing effective
therapies to restore hearing loss is challenging, owing to the limited
regenerative capacity of the inner ear hair cells. With recent advances
in understanding the developmental biology of mammalian and non-mammalian
hair cells a variety of strategies have emerged to restore lost hair
cells are being developed. Two predominant strategies have developed to
restore hair cells: transfer of genes responsible for hair cell genesis
and replacement of missing cells via transfer of stem cells. In this
review article, we evaluate the use of several genes involved in hair
cell regeneration, the advantages and disadvantages of the different
viral vectors employed in inner ear gene delivery and the insights
gained from the use of embryonic, adult and induced pluripotent stem cells
in generating inner ear hair cells. Understanding the role of genes,
vectors and stem cells in therapeutic strategies led us to explore
potential solutions to overcome the limitations associated with their use
in hair cell regeneration.
Full
Story
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December 2011
Researchers at Keele University in North
Staffordshire will be the first in the world to attempt to 'grow' new
cells in the ear that become lost and damaged with age. Age-related
hearing loss affects more than nine million people with over half of
people aged 60 and above affected to some degree. The researchers found
that in some cases hearing begins to decline when fibrocytes, cells in the
inner ear which usually manage levels of potassium and sodium, start to
degenerate. Once these cells have died and no longer function correctly,
other parts of the inner ear can become permanently damaged, leading to
increased loss of hearing and possible deafness. Dr Dave Furness, from
Keele University's school of life sciences, has been working for three
years on a study funded by Deafness Research UK and The Freemasons Grand
Charity to look into the causes of age related hearing loss. Now, Dr
Furness and his PhD student Jacqueline Tickle have begun the next phase of
the research, which will explore whether replacement fibrocytes and
fibrocyte stem cells can be successfully grown and implanted into the
ear. If successful, the research could pave the way towards the
prevention of age related hearing loss.
Full Story
