Stem cells delay paralyzing disease
Mon Oct 16, 2006
3:08 PM ET
By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - Human fetal stem cells can graft onto the
spines of rats and delay some of the paralyzing symptoms of motor neuron
disease, commonly known as
The new cells were resistant to the disease, also known as
amyotrophic lateral sclerosis or ALS, the researchers said.
A company associated with the researchers is incubating batches of
the human cells, taken from an aborted fetus, and hopes to market them as a
treatment for several sorts of paralyzing conditions.
"We were extremely surprised to see that the grafted stem
cells were not negatively affected by the degenerating cells around them, as
many feared introducing healthy cells into a diseased environment would only
kill them," said Dr. Vassilis Koliatsos of
The researchers, who published their findings in the journal
Transplantation, used specially bred rats that always develop symptoms of ALS
and die. Like people with the disease, they gradually become paralyzed until
they suffocate when breathing muscles stop working.
There is no cure for ALS and the causes are not clear. But the
Johns Hopkins team wanted to see if grafting new cells into the body might help
preserve some muscle function.
They used cells taken from an 8-week-old fetus, which had been donated by the mother after an abortion. Stem cells are partially developed but can give rise to a variety of different tissues if put into the right environment.
The
cells from the aborted fetus are not the same as embryonic stem cells,
currently at the center of a political debate in the
They are somewhat more malleable than adult stem cells but not as
plastic as embryonic stem cells.
In this case, the researchers took the cells from the developing
spine. These cells are already destined to become nervous system tissue and do
not elicit an immune rejection by the body, said Karl Johe, chairman and chief
scientific officer of Neuralstem Inc. in Rockville, Maryland.
NO CURE
The researchers only transplanted cells into the lower spinal
cords of the rats, in part because the animals are so tiny and the job is
tricky, said Johe. Because the upper spinal cord controls the upper half of the
body including breathing, there was no chance of curing the rats.
"They do develop symptoms and also they still die, but the
onset is more slowly developing and the longevity is extended," Johe said
in a telephone interview.
They injected the human fetal stem cells into adult rats not yet
showing symptoms and also killed some of the stem cells and injected them into
other rats to act as a control.
On average, the rats treated with live stem cells started losing
weight -- one of the first symptoms of disease -- after 59 days and they lived
for 86 days. In contrast, the rats given the sham treatment started to lose
weight at 52 days and only lived for 75 days.
While all the rats grew steadily weaker, the treated rats maintained
their ability to crawl up a slope for much longer than untreated rats.
After the rats died the researchers examined their spines and saw
that 70 percent of the transplanted cells had developed into nerve cells.
Johe said the company was growing and nurturing the cells and
hoped to create many batches of purified cells that could be used for
transplants for a range of patients with spinal cord diseases or injuries.
"If we see in a year ... really significant effects (in rats) then I think we could be ready for a (human) clinical trial in another year after that," Johe said.