Histological Response to a Fully Degradable Collagen Device Implanted in a Gap in the Rat Sciatic Nerve

Methods for engineering the regeneration of peripheral nerve in lesions have generally focused on the implementation of tubes as implants to bridge the defect. Previous study has shown that a highly porous analog of the extracellular matrix of a specific pore size range, ensheathed by a silicone tube, enhanced the regeneration of axons across gaps of 10 mm and greater in a transected adult rat sciatic nerve model. This study reports the histological findings resulting from implantation of a fully degradable collagen device comprising the collagen- glycosaminoglycan (GAG) analog in a collagen tube in a 10-mm gap in this animal model. Silicone tubes, with and without the collagen-GAG matrix, served as controls. Results indicated that axons had regrown into the midsection of the gap in all prostheses by 30 weeks; however, in the presence of the collagen-GAG matrix, the number and size of the axons appeared to increase. A layer of fibrous tissue approximately 100 µm thick, which contained fibroblasts, surrounded the silicone tubes but was not visible along the tube wall in any of the collagen tube prostheses. These findings show the promise of a fully degradable prosthesis for facilitating regeneration following peripheral nerve injuries.