NEW
YORK (AP)—For the first time, scientists have improved hearing in deaf
animals by using human embryonic stem cells, an encouraging step for
someday treating people with certain hearing disorders.
“It’s
a dynamite study (and) a significant leap forward,” said one expert
familiar with the work, Dr. Lawrence Lustig of the University of
California, San Francisco.
The
experiment involved an uncommon form of deafness, one that affects
fewer than 1% to perhaps 15% of hearing-impaired people.
And the treatment wouldn’t necessarily apply to all cases of that
disorder. Scientists hope the approach can be expanded to help with more
common forms of deafness. But in any case, it will be years before
human patients might benefit.
Results
of the work, done in gerbils, were reported online Wednesday in the
journal Nature by a team led by Dr. Marcelo Rivolta of the University of
Sheffield in England.
To
make the gerbils deaf in one ear, scientists killed nerve cells that
transmit information from the ear to the brain. The experiment was aimed
at replacing those cells.
Human
embryonic stem cells can be manipulated to produce any type of cell.
Using them is controversial because they are initially obtained by
destroying embryos. Once recovered, stem cells can be grown and
maintained in a lab and the experiment used cells from lab cultures.
The stem cells were used to make immature nerve cells. Those were then transplanted into the deaf ears of 18 gerbils.
Ten
weeks later, the rodents’ hearing ability had improved by an average of
46%, with recovery ranging from modest to almost complete, the
researchers reported.
And
how did they know the gerbils could hear in their deafened ears? They
measured hearing ability by recording the response of the brain stem to
sound.
The
gerbils were kept on medication to avoid rejecting the human cells,
much like people who get transplants of human organs, Rivolta said. But
that might not be necessary if the procedure proceeds to people, he
said. Scientists may be able to work with stem cells that closely match a
patient, or even use a different technology to make the transplanted
cells from a patient’s own tissue, he said.
Rivolta’s
team also reported making immature versions of a second kind of
inner-ear cell. Transplants of those cells might be able to treat far
more cases of hearing loss. But the team has not yet tested these in
animals, Rivolta said.
Yehoash
Raphael of the University of Michigan, who didn’t participate in the
work, said it’s possible the stem cell transplants worked by stimulating
the gerbils’ own few remaining nerve cells, rather than creating new
ones. But either way, “this is a big step forward in use of stem cells
for treating deafness,” he said.
Restoration of Hearing in the VGLUT3 Knockout Mouse Using Virally Mediated Gene Therapy
Source: The Associated Press
