In study, hope for stem cells

Professor Tracy McIntosh, who directs Penn's Head Injury Center, receives at least 20 e-mails a month from strangers, but none of them are spam.

The e-mails are from relatives of patients with brain injuries, and they hope that one of the leading experts on spinal cord injury and head trauma has a cure.

McIntosh is not yet able to answer many e-mails with solutions, but his recent research has left him and his team at Penn "hopeful" for future human applications.

In a four-month trial designed by Penn visiting fellow Peter Riess, Penn and Harvard University researchers lesioned the brains of 65 mice. The mice then received pre-fetal neural cell transplants. The transplanted cells automatically migrated to the damaged portions of the brain and nearly restored the mice's motor functions to original capacity.

The findings, published in the October edition of journal Neurosurgery, indicate that the motor functions of humans can be restored through similar neural stem cell transplants. Restoring cognitive functions in human brains will also be a possibility once researchers understand the chemical functions governing the transplants.

When researchers gain a full understanding of their discoveries, the success of the transplants will warrant a "wide range of applicability to disease in the nervous system" in humans, from Parkinsons to Alzheimers.

McIntosh is still careful to note that human experimentation is far from his next step.

Instead, he said he hopes to use the research information for another process -- to jump-start the brain's naturally occurring recovery cells that the transplants activate, so that eventually transplants will not be needed. McIntosh hopes to perform procedures with the use of certain chemical factors.

"I'm extremely encouraged, I'm very optimistic," McIntosh said. "I think this strategy will be very hopeful."

Fellow collaborator and Harvard neurologist Evan Snyder, however, hopes to speed the process along even faster. He plans to start using human stem cells in mouse transplants immediately.

Snyder does have definite plans to continue the collaboration, and the ambiguity of the next step is expected since "we don't particularly know the mechanism for what we observed," he explained.

Penn Neurosurgery Department Chairman Sean Grady was involved in the review of the study and attested to the general lack of clarity.

The results "are promising, but much work really needs to be done," Grady said. "We know how [the cells] integrate anatomically, but we don't know how they physiologically integrate."

Harvard researcher Yang Teng worked with Riess in Snyder's lab before the trial. Teng noted that the work was "well done" and that he "did see a clear improvement in... how much the tissue was damaged."

Teng's lab currently works with similar neural transplants with the addition of biodegradable polymers. He views McIntosh and Snyder's research findings as consistent with his own.

Teng, too, has his own next step proposal for the transplants. He said he would like to study the transplants at different time intervals following the brain lesions and further maximize genetically engineered neural cells to use in the transplants.

Whether Teng's lab will work in conjunction with McIntire's and Snyder's is still a future consideration. And the next step in the research is up in the air as well. But for now, the mice "are still really good. We're hopeful," McIntosh said.

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