Nerve-Muscle Sandwich Grafts: the Importance of Schwann Cells in Peripheral Nerve Regeneration through Muscle Basal Lamina Conduits

Abstract

An interposed segment of nerve was used to enhance the distance over which freeze-thawed muscle autografts will support effective peripheral nerve regeneration. Gaps were created in the sciatic nerves of adult Lewis rats. Regeneration through 1 and 1.5 cm freeze-thawed muscle grafts was compared to regeneration through nerve-muscle sandwich grafts in which muscle grafts of equivalent length were divided and a 2 mm segment of the distal nerve sutured between the two halves of the muscle, providing an intermediate depot of Schwann cells. Electrophysiological and morphological evaluation was carried out 40 weeks after operation. Despite lengthening the graft, and having four anastomoses instead of two, this manoeuvre enhanced nerve regeneration over each gap studied and for the 1.5 cm gaps compared favourably with perfect match nerve autografts. In addition, a number of grafts were examined at 7 and 14 days by Sl00 immunohistochemistry. Schwann cell migration was seen to proceed both proximally and distally from the intermediate segment at a rate similar to that from the distal stump. It is concluded that sandwich grafts may prove to be effective alternatives to cutaneous nerve grafts for peripheral nerve reconstruction.