Published on 06/22/2001

Collagen tubes show nerves where to regrow

NEW YORK, Jun 22 (Reuters Health) - Small collagen tubes placed between the ends of cut nerves can help the nerves to reconnect to each other, according to French scientists.

Tubes made from collagen, a protein important in maintaining the structure of skin and other tissues, have long been used successfully to foster the regrowth of nerves outside the spinal cord, according to Dr. Song Liu from University of Paris XI in Bicetre, France and associates.

In an earlier study, this research team showed that collagen tubes could support the reconnection of nerves to the upper spinal cord. In this study, reported in the July issue of Neurosurgery, the scientists examined whether collagen tubes could enable the reconnection of nerves severed from the lower regions of the spinal cord.

In the procedure, one end of the severed nerve was placed about 7 millimeters away (about one-quarter inch) from the other end, inside a collagen tube. In the earlier study, the nerve ends were placed only 3 millimeters apart.

Paralyzed rats treated with the collagen tube procedure showed some increase in muscle tension and resistance 6 to 9 months after surgery, the authors report, whereas untreated rats showed no such recovery.

Microscopic studies confirmed that nerves had regrown along the pathway provided by the collagen tubes, the report indicates, and electrical studies proved that nerve signals could be transmitted to the affected muscles.

Despite these findings, though, none of the treated animals were able to move spontaneously, the researchers report.

Still, the authors conclude, these results confirm that spinal nerves have the capacity to regrow into outside tissues through collagen tubes across a considerable gap.

"Although none of the animals exhibited voluntary use of the paralyzed hindlimb," Liu and colleagues write, "the return of some tension and resistance in the target (muscles) points to the possibility of (nerve regeneration)."

While this might provide a means to restore some muscle function in patients paralyzed after spinal cord injury, Dr. David Kline from New Orleans, Louisiana, cautions in a related commentary, "This study was done in rats, not in primates, and whether the growth from cord to nerve to muscle in higher-order animals would be sufficient to be functional remains to be seen."

SOURCE: Neurosurgery 2001;49.