Electrical Stimulation Accelerates Motor Functional Recovery in the Rat Model of 15-mm Sciatic Nerve Gap Bridged by Scaffolds With Longitudinally Oriented Microchannels

Abstract

Background. Electrical stimulation (ES) can enhance the regenerative capacity of axotomized motor and sensory neurons. However, the impact of ES on axonal regeneration and functional recovery has not been investigated in an animal model of a lengthy peripheral nerve defect. Objective. To determine whether ES accelerates axonal regeneration and functional recovery of a 15-mm sciatic nerve defect in rats. Methods. A 15-mm excision of the sciatic nerve was bridged with a chitosan scaffold with longitudinally or randomly oriented pores or with autologous grafting of the segment. In half of the animals with chitosan grafts, the proximal nerve stump was electrically stimulated for 1 hour at 20 Hz immediately after the nerve repair with the scaffolds. Axonal regeneration was investigated by retrograde labeling and morphometric analysis. The rate of motor functional recovery was evaluated by electrical nerve stimulation, behavioral tests of stepping, and histological appearance of the target muscles. Results. Axonal regeneration and motor functional recovery were improved by ES in animals that received longitudinal pore grafts as compared with others. The maximal number of axons that regenerated across the longitudinal graft was achieved 2 to 4 weeks earlier in rats with ES. In addition, the latency of compound muscle action potentials (CMAPs), the peak amplitude of CMAPs, and nerve conduction velocity were improved by ES. Stepping indices were better, with less atrophy of target muscle in ES rats managed with longitudinal pores. Conclusion. Brief ES may accelerate axonal regeneration and motor recovery after focal peripheral nerve transection when repaired with optimally tissue-engineered grafts.