Endoneurial extracellular matrix influences regeneration and maturation of motor nerve axons—A model of acellular nerve graft

Abstract

Clinical results of functional reinnervation after application of autogeneous nerve grafts obtained from cutaneous nerves have not always been satisfactory. A foreign extracellular condition especially for regeneration of motor axons is assumed to be one of the reasons explaining these unsuccessful results. The role of endoneurial extracellular matrix in regeneration and maturation of motor axons was studied using acellular nerve segment prepared from muscular or cutaneous nerves applied between stumps of transected motor branch of the femoral nerve. No differences were found in the numbers of regenerated axons and related motoneurons through the motor and cutaneous nerve grafts 1 month after operation. Two months from grafting, however, the numbers of motoneurons and regenerated axons were increased significantly in the motor grafts while these were decreased after regeneration through the cutaneous grafts compared with 1 month. Axons’ diameter and thickness of their myelin sheaths were similar in the cutaneous grafts 1 and 2 months after grafting. In comparison to 1 month, axons had larger diameter and thicker myelin in the motor than cutaneous nerve grafts 2 months from their application. Results of morphometric analysis indicate more beneficial extracellular conditions for regeneration and maturation of myelinated motor nerve axons in the acellular motor than cutaneous nerve graft. Generally, the results revealed that the endoneurial extracellular matrix of motor fibers has a positive effect on regeneration and maturation of motor nerve axons after lesion.