Stem Cell Transplants Possible Hearing Loss Treatment
Editor: You probably know that stem cells offer one possible hearing
loss treatment. Stefan Heller is one of the leading researchers in this
area.
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Stefan Heller's dream is to someday find a cure for deafness. As a
leader in stem cell-based research on the inner ear at the Stanford
University School of Medicine, he's got a step-by-step plan for making
this dream a reality.
It may take another decade or so, but if anyone can do it, he's the
guy to place your bets on.
"Everyone asks, 'How long before we do this?'" said Heller,
PhD, associate professor of otolaryngology, whose accent still bears the
trace of his native Germany. "I tell them the devil is in the
details."
But even at the national level, those in the research community
remain hopeful that Heller's work will reap successes sooner rather than
later. Heller will discuss his stem cell research during a panel
discussion Feb. 17 in San Francisco at the annual meeting of the
American Association for the Advancement of Science. The session is
titled "Hearing health: The looming crisis and what can be done
about it."
James Battey, MD, director of the National Institute on Deafness and
Other Communication Disorders, lauded Heller as "one of the leading
auditory neuroscientists" and points to his stem cell regeneration
research as a high priority for the institute.
Heller's vision is to develop a variety of possible cures for
deafness. For the past year and a half, since coming to Stanford from
Harvard, he's been focused on two paths: drug therapy-which could be as
simple as an application of ear drops-and stem cell transplantation into
the inner ear to remedy hearing loss.
Currently he's working on perfecting the steps toward eventual stem
cell transplantation into humans, with the goal of first curing deafness
in mice within the next five years. His lab is also busy studying the
ability of birds to regenerate the tiny hair cells in the cochlea. It's
these cells that convert the mechanical energy of sound into electrical
impulses that are sent to the brain so that a chicken, a mouse or a
human can hear. Chickens, like all birds, have the ability to
spontaneously regenerate these hair cells, which explains why there are
no deaf birds.
"This is promising because it means the genetic program for
regeneration exists somewhere in the vertebrate family," Heller
said. "We know there is an unknown signal to regenerate that we
could use, but we first have to find it."
The idea of using drug therapy to cure deafness has been at the back
of Heller's mind since he began researching the inner ear 12 years ago,
and it has become more plausible as a result of his lab's successes in
the field of stem cell research during the past seven years.
Heller gained international attention in 2003 for identifying stem
cells that reside within the inner ear. Since then, his research has
focused on using these stem cells to regenerate the critically needed
hair cells in the inner ear. Later in 2003, his group reached another
significant milestone: the team demonstrated that it is possible to coax
embryonic stem cells in a test tube to differentiate into hair cells-and
then also to have the stem cells differentiate after transplantation in
the ears of chicken embryos.
The two different approaches-new drugs and stem cell transplants-are
important because drug treatments are unlikely to help everyone. For
some people with genetically caused hearing disorders, he explained, no
drug is likely to help. "For them, stem cell transplantation may be
the answer," he said.
But for the majority of those with hearing loss, particularly in the
aging population, drug therapy could be the solution. As the population
has aged and noise pollution has grown more severe, health experts now
estimate that one in three adults over the age of 65 has developed a
handicapping hearing loss.
Coming up with the answers is a slow process, Heller said. "This
research takes time and money, but we remain hopeful we'll have some
principle answers soon."
Stanford University Medical Center integrates research, medical
education and patient care at its three institutions - Stanford
University School of Medicine, Stanford Hospital & Clinics and
Lucile Packard Children's Hospital at Stanford. For more information,
please visit the Web site of the medical center's Office of
Communication & Public Affairs at http://mednews.stanford.edu.
