An in vivo model to quantify motor and sensory peripheral nerve regeneration using bioresorbable nerve guide tubes

An in vivo preparation is presented to study the rate and time course of motor and sensory axonal regeneration. The cut ends of a transected sciatic nerve were inserted into each end of a 5-6 mm non-toxic and bioresorbable nerve guide tube to create a 4 mm nerve gap in adult mice. Subsequently, cell bodies in the ventral spinal cord and L3-L5 dorsal root ganglia that had regenerated axons across the gap were retrogradely labeled with horseradish peroxidase (HRP). The HRP was applied 3 mm distal to the nerve guide and was accessible only to axons that had regenerated through the nerve guide. Labeled cells were counted in 40 micron serial sections at 2, 4 and 6 weeks after initial nerve transection. The results indicate a significant increase in the number of labeled motor and sensory cell bodies over time. By 6 weeks after transection, approximately two thirds as many ventral horn motor cells and one third as many dorsal root ganglion sensory cells were labeled as in control non-transected animals. These data serve as a baseline to compare differential effects of additives to the nerve guide lumen in terms of sensory and motor neuron response.