Fetal spinal-cord allograft as a substitute for peripheral-nerve reconstruction: a preliminary experimental and histologic study

The aim of this preliminary experimental study consisted of an exploration of the suitability of fetal spinal-cord allograft as an alternative guiding conduit for bridging peripheral-nerve defects, since fetal tissue is considered to be less immunogenic than tissue from adults or maturely born individuals. The experiment was carried out with 10 Long Evans inbred rats. Within the control group, autologous sural-nerve grafts served to bridge an artificially created defect of 1.5 cm along the course of the sciatic nerve in the thigh of adult male rats. On the contralateral thigh, a defect of the same size was bridged by spinal cord, taken from 17- to 20-day old fetuses. Ten weeks thereafter, the reconstructed nerves were examined histologically. Compared to the autologous nerve grafts with optimal regeneration, the spinal-cord grafts showed less ingrowth of axons. But, surprisingly, an exceptionally long survival time of astrocytes and other nerve cells resulted while, at the graft margin, bundles of astrocytes apparently served as a conduit for ingrowing axons. Using fetal spinal-cord allograft to reconstruct peripheral-nerve defects may present a future alternative for coexisting methods, but further studies with longer follow-ups, a greater number of larger animals, and with the additional evaluation of immunologic interactions, should be attempted, to draw clear conclusions.