[Time limited immunosuppression in allogenic nerve transplant in the rat]

A rejection response of peripheral nerve allografts eliminates the Schwann cells without destroying the tubular architecture and leads to a regeneration of inferior quality. Under immunosuppression this rejection is prevented, and allogenic Schwann cells persist in the grafts, leading to a better regeneration result. In adult rats of the strains DA and LEW.1W, a 2,5 cm segment of the sciatic nerve was grafted. Under Cyclosporin A regeneration was allowed to take place for 12 weeks. Thereafter, immunosuppression was discontinued in one group and gradually reduced in another. Regeneration quality was compared after an additional six weeks in comparison to an autologous control. Best regeneration was observed in the autologous control; no statistical differences were observed between the two experimental groups. Gradual reduction of immunosuppression did not result in an atraumatic replacement of donor derived Schwann cells by recipient derived ones. Allogenic nerve grafting needs continuous immunosuppression, which to date precludes it from clinical application.