Science / Medicine : Severed Nerves Joined

<i> Times science writer Thomas H. Maugh II reports from the 196th National Meeting of the American Chemical Society in Los Angeles</i>

Severed nerves in mice can be induced to grow across a gap and rejoin by connecting them with an artificial polymer that forms a scaffolding for the regenerating nerve cells, according to materials scientist Ioannis V. Yannas of the Massachusetts Institute of Technology. The technique may eventually be used to restore nerve function in the limbs of humans, a procedure that is now very difficult if a gap exists between the severed nerve ends.

Yannas had previously used a sponge-like scaffolding composed of collagen--a tough, fibrous protein that mechanically reinforces connective tissues in the body--and a sugar-based polymer to prepare a synthetic skin that is now undergoing clinical testing.

To repair nerves, he used the material to fill a narrow silicone rubber tube and inserted the severed ends of the sciatic nerve in the legs of rats. After much experimentation, he found a formulation of the polymer that would allow the nerves to grow across a half-inch gap over a period of six weeks, restoring as much as 50% of the nerve function.