stroke,
the leading cause of serious, long-term disability in
the United States, “is a disease where we do not
have good treatments,” says neurosurgeon Gary
Steinberg. Americans spend $30 billion a year on stroke
recovery and rehabilitation, but doctors have no way
to repair the damaged brain tissue.
That may soon change. Researchers in Steinberg’s
lab have demonstrated that human fetal stem cells, when
transplanted into the brains of laboratory rats with
induced strokes, can migrate toward the damaged location
and turn into neurons and support cells. On average,
one-third of the stem cells survived, migrating up to
1.2 millimeters—“a very long distance,”
Steinberg says. The researchers hypothesize the cells
migrated in response to a chemical signal released by
the animals’ brains to indicate damage.
“This is the first time human neuronal stem cells
have been shown to survive, migrate and differentiate
in an animal stroke model,” Steinberg says. The
results were published last year in the Proceedings
of the National Academies of Sciences with Tonya
Bliss, a research associate, and Steven Kelly, now at
the University of Bristol, as co-first authors.
The cells they used were isolated five years ago by
StemCells Inc., a Palo Alto company founded by study
co-author and pathology professor Irving Weissman. They
are of a sufficient grade and quality to be used for
future clinical trials in humans.
But first, Steinberg and his team have to show that
the cells can restore motor or sensory functions in
animals. “With advances in stem cell research,
our [increased] understanding of how brains develop
and repair themselves, and molecular biology and gene
therapy techniques, we now are able to think about repairing
tissue,” he says. Scientists, he points out, are
pursuing many potential brain-tissue transplants as
treatments for stroke; stem cell transplants may or
may not be the most therapeutic.
The recent experiment “is very exciting work,”
he adds. “But we still have quite a bit of preclinical
work to do before we’re ready to start treating
stroke patients using these cells.” He plans to
investigate what enables the stem cells to survive in
large numbers, migrate and differentiate, to see whether
those processes can be enhanced.
Steinberg is already getting calls about the findings
from people who’ve had strokes, as well as those
who suffer from degenerative diseases or traumatic brain
injuries. Clinical trials for stroke are a few years
off, so he tells callers, “We’re not ready
yet, but we’ll take your name.” |
