Hope for Repair of Spinal Injuries? : Tissue Research at UCSD Aids Brain Damage in Rats

An implanted bridge of tissue has stimulated the regrowth of nerve cells to fix brain damage in rats and may one day help make similar repairs in the thousands of people who suffer spinal cord injuries each year, scientists reported Thursday.

Researchers at UC San Diego and the La Jolla Cancer Research Foundation used microscopically thin strips of tissue made of fibrous material taken from human placentas. These strips were implanted in rat brains in which the hippocampus and septum of the brain had been disconnected. The implant stimulated growth of nerve cells across the bridge to reconnect the two sections.

Human tests of the technique are “far, far off. Years and years. These are just the very first preliminary experiments in animals. I’m not sure this is what we would ever use in humans,” said Eva Engvall, a biochemist at the La Jolla foundation and co-author of the report in the journal Science.

The key to stimulation of repair is a protein in the tissue graft called laminin, a protein known to be a potent stimulator of nerve cell growth in test tube experiments.

The protein can be extracted, Engvall said, and could be used to generate the same kind of response as the tissue did. She said experiments using the pure protein in rat brains have not yet been done.

The next step, said Fred Gage, an associate professor of neuroscience at UCSD and a co-author of the report, is to see if the restored connections make any difference in the animal’s behavior or memory.

The most important application of the technique in humans, if it works out, could be in those who suffer spinal cord damage, he said. But it is still unknown whether the new cells that grow on a bridge are sufficient replacements for those that die during injury.

Spinal cord injuries, caused primarily by automotive and sports accidents, paralyze 15,000 to 20,000 Americans each year, according to the American Paralysis Assn.

Many scientific teams have been experimenting with ways to regenerate nervous system and brain tissue damaged by disease or accident. One technique publicized recently is grafting of fetal brain or nerve cells.

The supply of these tissues is limited, however, the team wrote.

“What everybody’s trying to substitute that with is something that wouldn’t contain fetal material,” such as the purified protein, Engvall said.

Human placentas, which are usually discarded, are more easily obtained, she said.