Nerve grafts with various sensory and motor fiber compositions are equally effective for the repair of a mixed nerve defect

Abstract

Autologous, cellular nerve grafts are commonly used to bridge nerve gaps in the clinical setting. Sensory nerves are most often selected for autografting because of their relative ease of procurement and low donor site morbidity. A series of recent reports conclude that sensory isografts are inferior to motor and mixed nerve isografts for the repair of a mixed nerve defect in rat. The aim of the present study was to determine if the disparity reported with cellular graft subtypes exists for detergent decellularized, chondroitinase ABC processed nerve grafts. We hypothesized that processing removes or neutralizes the inferior properties attributed to sensory nerve grafts. Saphenous (cutaneous branch), femoral quadriceps (muscle branch) and tibial (mixed trunk) nerve grafts 5 mm in length were used in tensionless reconstruction of syngenic rat tibial nerves. Nerve regeneration through the grafts and into the recipient distal nerve was evaluated 21 days after grafting by two methods, toluidine blue staining of semi-thin sections (myelinated axons) and neurofilament-immunolabeling (total axons). Contrary to previous reports using this grafting scheme, we found no significant difference in the myelinated axon counts for the three cellular graft subtypes. Moreover, total axon counts indicated cellular saphenous nerve grafts were more effective than the quadriceps and tibial nerve grafts. A similar though less pronounced trend was found for the decellularized processed grafts. These findings indicate that nerve graft composition (sensory and motor) has no substantial impact on the short-term outcome of nerve regeneration in a mixed nerve repair model.