该是同样的研究.
Could stem cells help this boy to see?
This year, we may find out
By MAYRAV SAAR
Last Updated: 12:12 PM, January 2, 2011
An inherited degenerative disease robbed Ryan Rapoport, 10, of his vision in
seven quick months.
But the Seattle fifth-grader now sees hope on the horizon: After several
years of scrutiny, the Food and Drug Administration gave the green light to
a California biotech company to use human embryonic stem cells
<http://www.nypost.com/t/Stem_Cells> as a treatment for the disease that
robbed Ryan of his sight.
Only the second company to be approved to use embryonic stem cells in a
clinical trial, Santa Monica's Advanced Cell Technology (ACT) expects to
begin testing the treatment as early as February, said the company's chief
scientific officer Dr. Robert Lanza.
TEST CASE: Ryan Rapoport, 10, hopes the direct injection of retinal stem
cells into his eyes will reverse his blindness caused by Stargardt macular
dystrophy.
"I have felt pretty hopeless," said Darrin Rapoport, Ryan's father. "This
has literally allowed me to smile again."
Heralded a decade ago as the savior of all that ails man, embryonic stem
cells were supposed to provide cures for everything from spinal-cord
injuries to heart disease.
Stem cells, which are abundant in embryos, have the ability to form into any
kind of human cell -- eyes, livers, intestines -- giving hope that
scientists could one day "grow" healthy human tissue to replace damaged or
diseased organs.
But research into the field was outlawed by the Bush administration, which
lumped the work into the cultural debate about abortion.
In 2001, Bush banned all federal funding of research on embryonic stem cells
beyond those that used the 21 cell lines in existence at the time, scaring
away venture capitalists and limiting what researchers could do.
Many scientists moved on to different areas of research. Some worked with
less malleable stem cells from tissues of adults, with mixed results.
In March 2009, <http://www.nypost.com/t/Barack_Obama> President Obama
reversed the Bush policy. Now the issue is back in the courts, with
embryonic stem-cell researchers expressing cautious optimism that research
using those unspecialized cells, mostly harvested from unused embryos from
fertility clinics, will begin anew.
At least a dozen scientists in California alone are expected to apply for
FDA clinical-trial approval in the next four years for research into
treatments for diabetes, <http://www.nypost.com/t/Alzheimer's_Disease>
Alzheimer's disease and multiple sclerosis.
But the first two approved clinical studies may be the most amazing --
making the paralyzed walk and the blind see.
For safety's sake, Advanced Cell Technology's initial trial for sufferers of
the disease Ryan suffers from, Stargardt macular dystrophy, will be limited
to only 12 patients -- all of them adults with an advanced form of the
condition.
One of the benefits of working with the eye is that it is protected from
body's immune system, so injecting foreign cells into the eye will not
likely cause the body to reject the treatment.
Another benefit is that the eye is a window to the, well, the eye.
"You can just look into the eye and see individual retinal cells. If
anything started to grow, we could see it in real time," Lanza said.
For the last decade, researchers have been grafting adult stem cells
<http://www.nypost.com/t/Stem_Cells> taken from the limbus of a patient's
own eye to treat corneal blindness. Unlike those limbal cells, embryonic
stem cells have the ability to become any kind of new, healthy cell, in this
case RPE.
The main concern of regulators and doctors monitoring this study is that
the very malleability that embryonic stem cells are prized for also make
them potentially dangerous.
The cells scientists will inject into patients will be stem cells that have
been turned into RPE cells by scientists -- but what if a few
"undifferentiated," or unspecialized, cells ended up in the mix?
Regulators need assurance that patients would be protected against
unintended growths.
"You don't want to end up with a tooth growing in your brain," Lanza said.
The company underwent intense scrutiny to make sure none of the cells in
their trials were undifferentiated -- or liable to turn into something other
than RPE.
"They wanted to make sure there were no icebergs beneath anything," Lanza
said of the FDA.
The company was tasked with proving the purity of their cells -- a benchmark
they believe other companies searching for FDA approval will have to match.
LANZA started his career in this field in 1999, back when the mere mention
of "embryonic stem cells," invoked images, as he puts it, "of little embryos
with arms and legs being pulled apart."
As political fervor built, he watched colleagues leave the country in search
of more hospitable climes.
But he stayed at ACT, working through repeated losses of funding,
<http://www.nypost.com/t/Federal_Bureau_of_Investigation> FBI interventions
and death threats.
"I thought there was a 50/50 chance that I wouldn't be around to see this
through. It was serious," he said. "When I went out walking, I'd be
listening for people in the bushes. When we picked up our first cells, we
sent bodyguards."
After the 2008 elections, however, Lanza said the shouts of "Murderer!" come
much less frequently. This, he attributes to a greater understanding of what
embryonic stem-cell research is.
"My goal is to do something where I can make a difference and help," he
said. "I believe in this, and I knew in the end, that once people are
educated, they'd start to understand this is going to help people."
One of the people who also believed is William Caldwell, now chairman and
CEO of ACT. Caldwell and his wife made personal loans to the company to help
keep it afloat during some of the early days.
"The company was run by scientists, and in order for them to survive, they
had to sell off non-core assets," Caldwell said.
ACT received a nod from the FDA in November, a few months after the agency
gave approval to Menlo Park, Calif.-based Geron Corp. to test embryonic
stem-cell treatments on patients with spinal-cord injuries.
Using research that began in 2004, University of California-Irvine scientist
Hans Keirstead discovered that, using embryonic stem cells, he was able to
restore paralyzed rats' ability to walk. Geron is now exploring the
treatment's effectiveness on humans in several medical centers across the
country.
ACT and other companies watched the Geron application process with great
interest, particularly when the FDA placed a clinical hold on Geron's drug
after some of the animals injected with the treatment developed small cysts
within their spinal cords.
Geron developed new procedures to minimize the risk, and the FDA lifted its
hold.
The legwork by ACT and Geron is expected to pave the way for other companies
looking to create similar treatments for debilitating and life-threatening
diseases.
ACT recently filed a request to begin trials to test a potential treatment
for age-related dry macular degeneration, a chronic eye disease that causes
central vision loss by deteriorating a layer of tissue on the inside back of
the eyeball.
Associated with the elderly, dry macular degeneration affects 2 million
people in the United States.
And in the next few years, the company plans to pursue therapies for making
red blood cells and platelets. |
