Successful implantation of Schwann cells in acellular muscles

Acellular muscle grafts can support axonal regeneration over short gaps. Du e to the lack of viable Schwann cells in the grafts, failure of regeneratio n is evident with increasing gap lengths. To create a biological nerve cond uit, Schwann cells were implanted into acellular muscle. The grafts were th en incubated in vitro and assessed histologically and morphometrically. For cultivation of the Schwann cells, rat sciatic nerves were allowed to prede generate to obtain a high cell yield. Rat gracilis muscles were harvested a nd made acellular by a liquid nitrogen treatment. After Schwann cell implan tation, the muscles were incubated in vitro for 2, 5, and 7 days. S100-immu nostaining, NGF, and N-cadherin, characterized the Schwann cells within the muscle. Viability was assessed by fluoresceine-fluorescence staining. Prol iferation was determined by BrdU-DNA incorporation. Cell implantation did not to affect Schwann cell viability. Cells were seen throughout the entire length of the muscle basal lamina. They aligned and formed a cell column. Immunostained for S-100, implanted cells showed 100 p ercent staining. N-cadherin and NGF were expressed by all of the S-100 posi tive cells. Predegeneration is considered to be a highly efficacious method, if a high yield of activated Schwann cells is required. The successful implantation o f the cells into an acellular muscle provides the possibility of a biologic conduit, offering the advantage of large basal lamina tubes serving as a p athway for regenerating axons. It also provides the beneficial effects of v iable Schwann cells that produce neurotrophic and neurotropic factors to su pport axonal regeneration. Functional outcomes require evaluation in furthe r in vivo studies.