Stem Cell Therapy Studies For Stroke, Cerebral Palsy Prepare For
Clinical Trials
ScienceDaily (Jan. 30, 2008) — Finding answers about optimal dosage
and timing for stem cell therapy in adults with strokes and newborns
with ischemic injuries is a goal of two new federally funded studies.
The answers are critical before clinical trials can begin, says Dr.
Cesario V. Borlongan, neuroscientist at the Medical College of
Georgia and Charlie Norwood Veterans Affairs Medical Center. He is
principal investigator on the National Institutes of Health grants
totaling $6 million that also will explore long-term benefits of cell
therapy.
If these additional laboratory studies replicate the promising
results of the pilot studies, which indicate about a 25 percent
improvement in recovery over controls, MCG and VA researchers hope to
begin clinical trials in new ischemic injuries in adults and children
within two years.
"We are looking at different procedures that we can adopt from the
laboratory for the clinic," Dr. Borlongan says. "We have at least 10
years of basic research that clearly shows that stem cells have the
potential to be a new therapy for adult stroke."
"This is a whole new paradigm, a totally different way of targeting
disease," says Dr. David Hess, chair of the MCG Department of
Neurology and co-investigator. Clot buster tPA is the only drug that
is FDA-approved to treat ischemic strokes; an often-delayed diagnosis
and a three-hour treatment window mean only a small percentage of
patients get it.
Drs. Hess and Borlongan say cell therapy could eventually be used
alone or in conjunction with tPA, if recovery is not sufficient.
Pilot studies indicate cell therapy can be of benefit up to seven
days after a stroke but that two days out is the optimal time of
delivery. "This will allow us to enroll patients who get tPA, give us
plenty of time to assess them and prepare the cells," says Dr.
Borlongan.
Their success in an adult stroke model led the researchers to explore
the potential for helping babies recover from hypoxic ischemia, a
loss of blood and oxygen that can result in cerebral palsy, broadly
defined as a brain injury that occurs before or during birth.
Ischemic brain injury accounts for about 10 percent of cerebral palsy
and about 80 percent of strokes.
They found young, developing brains more adaptable to injury and
better able to recover even without intervention. "Very young
patients may be the biggest beneficiaries of cell therapy," says Dr.
James E. Carroll, chief of the MCG Section of Pediatric Neurology and
a co-investigator. "Our hope is that cell therapy will speed
recoveries of babies who have experienced a brain injury at birth,"
he says. "You want to increase the spontaneous recovery, enhance the
neurogenesis that is already occurring in the brains of these young
patients," adds Dr. Borlongan.
They have models for mild, moderate and severe ischemic injury to
reflect damage that can result from scenarios such as an umbilical
cord wrapped around the fetus' neck or placental abruption, which
disrupts the fetus' source of oxygen and nutrients. Researchers
expect that cell therapy likely would be used as an adjunct to
hypothermia, a new FDA-approved treatment for hypoxic ischemic injury
in babies that appears to improve outcomes by reducing metabolic
rates, including oxygen requirements, in the hours following an
injury.
Given intravenously, the adult, bone marrow-derived stem cell line,
developed by Cleveland-based biopharmaceutical company Athersys,
Inc., seems to hone in on the area of injury where it works multiple
ways. While only a small fraction of the cells actually survive and
mature into neurons – more survive in the baby model than the adult –
trophic factors they secrete significantly enhance recovery of brain
cells injured by lack of oxygen and help grow new blood vessels.
Nothing seems to help the core of the ischemic area in stroke, which
is formed within hours of injury; even when cells are placed directly
into the core, they do not survive in the area, which is devoid of a
blood supply, Dr. Borlongan says. However the cells and their trophic
factors can dramatically reduce the penumbra, the area of damaged
cells surrounding the core, an area that can continue to grow several
days after injury.
Interestingly, these undifferentiated stem cells don't seem to
interest the immune system, so immunosuppression is not required as
it typically is for organ transplants, even when a human cell is
placed in a rat, Dr. Borlongan says. Also, pilot studies that have
followed rat models for two months after transplant – a long time
considering the average rat lives two years – haven't found any signs
of tumor formation, which is a concern with stem cells. The new
studies will follow transplants for six months, to ensure that
efficacy and safety hold up, Dr. Borlongan says.
They'll explore dose ranges between 400,000 and 40 million cells. "We
want to see, if we implant more cells, will it be more beneficial?"
says Dr. Borlongan. "It may not be the more the merrier."
In preparation for clinical trials, the researchers already have
clinical advisory groups for the studies and have begun submitting
grant proposals and talking with the FDA. Smaller studies in non-
human primate models may also be required before clinical trials
begin, Dr. Borlongan says.
Athersys scientists Robert J. Deans and Robert W. Mays are co-
investigators on the studies.
Adapted from materials provided by Medical College of Georgia.
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MLA Medical College of Georgia (2008, January 30). Stem Cell Therapy
Studies For Stroke, Cerebral Palsy Prepare For Clinical Trials.
ScienceDaily. Retrieved January 30, 2008, from
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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