Human Marrow Helps Rats Recover from Stroke

Show improvement two weeks after 'remodeling' transplant

MONDAY, Aug. 26, 2002 (HealthDayNews) -- Transplants of human bone marrow cells may prove to be a successful treatment for stroke and other brain and spinal cord injuries.

A new study finds that animals that had strokes recovered well two weeks after the injury when they received human bone marrow.

The donor cells used in the research "prompt the brain to remodel," says Michael Chopp, vice chairman of neurology and scientific director of the Neuroscience Institute at Henry Ford Hospital in Detroit. Results of the study he led appear in tomorrow's issue of Neurology.

About 600,000 Americans have strokes each year, according to the American Heart Association, and about 4.5 million stroke survivors are alive in the U.S. today. Stroke occurs after blood supply is cut off to part of the brain; if blood flow is obstructed more than several minutes, injury to the brain cells is permanent and tissue dies in that area of the brain.

Researchers have been trying for years to find a way to get the brain back to "normal" in the wake of a stroke. They also have been trying to improve on current treatments, one of which must be administered within three hours or less of the stroke.

Chopp says his approach is different from that used by other researchers -- as well as his own previous work. Rather than expecting donor cells to develop into replacement cells, Chopp says the more effective strategy is to expect the transplanted cells to activate the brain into remodeling.

"The donor cells' job is not to replace the damaged cells," he says. Instead, they are like contractors sent in to remodel. "They do not replace the inhabitants."

In the study, Chopp used adult human bone marrow cells, which are mature cells but still capable of differentiating into other cells. After strokes were induced in rats, Chopp administered the cells intravenously one day after the stroke into one group of rodents. Another group got a different type of cell, and a third group was untreated to serve as the controls.

Two weeks later, the group treated with the bone marrow cells did better on neurological exams and a test of sensory abilities than the other groups. The group administered the bone marrow cells also produced more substances that stimulated the brain cells to grow, and had less cell death in the area affected by the stroke.

The bone marrow cells migrated to the site of the injury. "The way the cells we used are promoting functional benefit is not by becoming brain cells but by secreting factors [such as growth factor] and proteins that activate the inherent restorative mechanisms in the brain," Chopp says. The cells work by activating production of new brain cells, new blood cells, and new synapses (junctions that permit passages of nerve impulses), he says.

The study breaks new ground, says Dr. Thomas A. Kent, professor of neurology and pharmacology at the University of Texas Medical Branch in Galveston, who co-authored an editorial in the journal about the study.

"There is a tremendous need for other approaches [to treat stroke]," he says. One of the current treatments for stroke, tissue plasminogen activator (t-PA), a clot-busting drug, must be administered within a three-hour window of symptoms, and many victims don't get to a hospital in time for this option.

But the cell therapy, if it bears out, would have a longer time span within which to work, Kent says.

He offers some caveats along with the praise, however. "There will need to be more animal studies, particularly about what happens to these cells after a long period of time in the brain," he cautions. But he is generally hopeful about the therapy, which is already used clinically in the treatment of cancer.

What To Do

For more information on what a stroke is and how it is treated, visit the American Heart Association or the National Stroke Association.

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