Scientists from the Medical College of Georgia and the University of South Florida in Tampa used human cord blood, which is rich in stem cells, to treat rats who had been given a stroke. By using mannitol, a drug that makes it easier for chemicals to reach the brain, the scientists were able to reduce the damage by 40 percent and the animals were able to return to 70 percent function, said lead author Cesario V. Borlongan, a neuroscientist at MCG and the Augusta Department of Veterans Affairs Medical Centers.

The findings were published in this month’s edition of the journal Stroke. While embryonic stem cells can potentially turn into any kind of cell, the cord blood cells secrete nerve growth factors that aid repair and rally other stem cells to the damage.

The researchers hope to start testing it in primates and perhaps in two years will begin trials in humans, said co-author Paul Sanberg, distinguished professor of neuroscience at South Florida.

As Dr. Sanberg spoke Tuesday, actor Michael J. Fox was appearing on his Tampa campus on behalf of the Democratic National Committee to talk about using the embryonic cells to treat Parkinson’s disease, which he has. In August 2001, President Bush ordered that federal research funding be restricted to embryonic stem cell lines already in existence and that it not be used on any new cell lines, which are created from donated surplus embryos. The embryos are destroyed in harvesting the cells, and some see that as ending a potential life, even though the embryos would be destroyed anyway.

Patient advocates in diseases ranging from Parkinson’s to Alzheimer’s, including former first lady Nancy Reagan, have called for easing the restriction to spur research, and it is likely to become a topic in the upcoming presidential debates.

The restriction has severely limited the availability of the embryonic stem cells, Dr. Borlongan said.

“It’s been very difficult for us to even be on the waiting list to get stem cells,” he said. That’s why cord blood is a good solution as it is normally thrown away after the birth.

“It avoids the logistical and ethical concerns associated with the use of embryonic cells,” Dr. Borlongan said.

“Plus there’s almost an unlimited supply,” Dr. Sanberg said. MCG and a firm in Tampa that Dr. Sanberg co-founded are already banking donations.

In addition to supply, the cord blood has a number of potential advantages over so-called clot-busters, which have to be given within three hours, can’t be given to those who have bleeding in the brain and can have serious side effects, Dr. Sanberg said.

“It’s potentially lethal, and you can’t give it to hemorrhagic stroke, where this we feel we can give to both bleeding strokes and nonbleeding strokes,” Dr. Sanberg said. It can also be given later than three hours.

“In this case, the best time appears to be a day to four days after the stroke,” Dr. Sanberg said. “And that’s really important clinically, because when you look at the average time that a stroke patient takes to get into the hospital, it’s not three hours. It’s 12-13 hours.”

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