They claim cures might be found for debilitating diseases.
http://inq.philly.com/content/inquirer/2001/07/16/front_page/STEMSCI16.htm
Monday, July 16, 2001
As President Bush agonizes over whether
to allow taxpayer-funded research on stem cells from human embryos, neurologist
Jeffrey Rothstein is injecting these cells into mice to see whether they
can slow the relentless nerve degeneration that comes with amyotrophic
lateral sclerosis, or Lou Gehrig's disease.
Rothstein and his colleagues at Johns
Hopkins University, who are privately funded, are transplanting so-called
embryonic stem cells into mice with a condition similar to ALS, which often
starts with weakness in the arms or legs and eventually robs the patient
of the ability to walk, talk, and, in the end, breathe.
Other scientists around the country,
most of them testing the controversial embryonic cells in mice or rats,
are looking at their potential for some of the most devastating conditions
- brain diseases such as Parkinson's and Alzheimer's, spinal-cord injuries,
and the irreparable scarring caused by heart attacks.
The research is so new and the power
of these cells is so little understood that scientists don't know whether
stem cells will revolutionize medicine. But they will never know if they
aren't allowed to study them, they argue.
Adding fuel to the debate over using
embryos is new evidence that stem cells taken from adult donors show some
of the same promise.
Currently, research is allowed on
embryo stem cells only if private money is used, but that restriction has
made such research impossible for many scientists, who can't gather sufficient
funds. Wise Young, director of the W.M. Keck Center for Collaborative Neuroscience
at Rutgers University in Piscataway, Middlesex County, said stem cells
represent one of the most promising avenues of research for spinal-cord
injury. If Bush decided to allow federal funding for work with these cells,
"that would stimulate a flurry of research in my lab and other labs."
"Stem cells are a very major issue
to the spinal-cord injury community," Young said. "Why should they be penalized
for the religious beliefs of a few?"
The promise of these embryonic stem
cells comes from their seemingly magical ability to transform themselves
into any of the more than 100 kinds of tissue that make up the human body.
First isolated and grown in the lab
in 1998, the cells have spawned visions of new spinal-cord tissue for paralysis
patients, pancreatic cells to cure diabetes, heart cells that would repair
the scarring of a heart attack, reinforced bone for osteoporosis, or new
skin for burn victims.
Currently, some embryonic stem cells
are taken from aborted fetuses, isolated, and then allowed to multiply
in culture dishes. Others come from the microscopic embryos that are routinely
created and either frozen or destroyed in fertility clinics. Such embryos
develop for just a handful of days and, never progressing beyond the stage
of a cluster of "undifferentiated" cells, have yet to specialize as different
types of tissues.
Lobbying against using embryonic
stem cells are the Catholic Church and others who believe that life begins
at conception with a fertilized egg.
These groups argue that there is
no need to exploit human embryos, citing reports of stem cells being obtained
from bone marrow and other sources in adults, either live donors or cadavers.
Scientists are not yet ready to say
whether adult cells would work as well as embryonic cells. Not enough research
has been done, they say, and almost all of it has been in animals.
So far, embryonic stem cells have
been turned into more than 100 different types of cells, far more than
adult stem cells. Also, embryonic stem cells can reproduce indefinitely
in the lab; adult stem cells eventually die.
Peter Donovan, who conducts stem-cell
research at Thomas Jefferson University Hospital, said it is possible that
the medical community may decide never to use embryonic stem cells, opting
instead for the adult cells. But to learn how to use any of these stem
cells, he said, "we'll need to study both types."
John McDonald at Washington University,
St. Louis, has been studying the embryonic stem cells as a treatment for
paralysis. In 1999, he injected the severed spinal cords of paralyzed rats
with rat stem cells.
While the rats didn't recover completely,
they gained function - some degree of mobility, sensitivity, bladder control
- the kinds of things that can be important to people with spinal-cord
injuries. And such success may not ever come from the adult stem cells,
he argued.
He has since begun using human embryonic
stem cells in rats and mice, with similar results.
McDonald just started testing this
technique, using stem cells from pig embryos, on people paralyzed by spinal-cord
injuries. There are no results yet from the one patient who has received
treatment.
Meanwhile, Ira Black of the New Jersey
College of Medicine and Dentistry, working with former Hahnemann University
professor Darwin Prockop, who is now at Tulane in New Orleans, is concentrating
on adult stem cells. They obtained such cells from bone marrow taken from
student volunteers.
Black and Prockop knew that stem
cells from bone marrow could become bone, cartilage, fat and muscle. But
last year they proved they could also transform it into brain tissue. That
led them to inject the stem cells into rats that had been given a form
of Parkinson's disease. The cells took up residence in the brain, where
new brain tissue was needed, Prockop said, and the animals showed some
improvement.
Prockop said the bone marrow stem
cells are now being tested as a treatment for a genetic abnormality called
brittle bone disease, which causes people to fracture at the slightest
impact. In animals, the cells seem to migrate to the deficient skeleton.
Human trials are expected soon.
Some opponents of embryo research
point out that some patients are now getting stem cells from umbilical-cord
blood, taken when babies are born. But so far such cells have only produced
blood cells, limiting their use to blood diseases such as leukemia.
The first study to compare the benefits
of embryonic stem cells with adult cells is the ALS work on mice being
done at Johns Hopkins.
Early results, in which they transferred
mouse stem cells to mice, showed "dramatic" improvement for the mice that
got embryonic stem cells, Rothstein said, but not for the ones that got
cells from other sources. The Hopkins group has since begun transplanting
human stem cells of different types into the mice. The results, Rothstein
said, are confidential, having been sent to a journal but not yet published.
Rothstein hopes the mice experiments
will answer some questions beyond ALS.
"We're one small disease, but it
has a pretty big impact," said Rothstein. Their research could point to
similar treatments for multiple sclerosis, Parkinson's disease, paralysis,
or Alzheimer's.
Even if the adult stem cells prove
superior in the ALS trial, Rothstein remains convinced that embryonic stem
cells hold tremendous promise. He said that any decision to continue the
federal funding ban would be "a bad mistake."
Donovan of Jefferson argues that
embryonic cells hold keys to our understanding of the way life works. Virtually
every cell in the body carries the person's complete genetic code, and
yet the cells take myriad forms and functions. Some mysterious mechanism
seems to tell them whether to become bone, muscle, organ, nerves, or blood.
Stem cells may hold the secret behind
the cells' ability to find their identities, and, combined with the knowledge
from the human genome project, could give scientists a huge insight into
the way life is put together.
Such an understanding would be critical,
Donovan said, for making the stem cells truly useful in medicine.
Still, he cautioned that impressive
new ideas - such as gene therapy - don't always live up to the public's
hopes.
"We don't want to promise too much
too soon."
By Faye Flam
INQUIRER STAFF WRITER