Polycaprolactone (PCL) 導管對神經再生的效應

Abstract

We established histopathological and neurophysiological approaches to examine whether different designs of polycaprolactone-engineered nerve conduits (hollow versus laminated), could promote nerve regeneration as autologous grafts after transection of sciatic nerves. Changes of various antigen profiles in Schwann cells and regenerated axons within the hollow and the laminated conduits were examined by immunohistochemistry. Nerve growth factor receptor (p75) and glial fibrillary acidic protein (GFAP) were up-regulated in the laminated conduit with fewer expressions of phosphorylated neurofilaments. Different results with down-regulations of p75 and GFAP and abundant expressions of phosphorylated neurofilaments were observed in the hollow conduit and the autologous graft. The findings revealed that the hollow conduit had better regeneration efficacy than the laminated one. For evaluating the long-term axonal regeneration and the functional recovery after conduit grafting, further quantitative assessments included morphometric analysis at the level of sciatic nerve, neuromuscular junction (NMJ) and gastrocnemius muscle, and nerve conduction studies on sciatic nerves were performed at POM 3 and POM 6. Six months after nerve grafting, the nerve fiber density in the hollow-conduit group was similar to that in the autologous-graft group; the laminated-conduit group only achieved ~20% of these values. The consequences of these differences were reflected in nerve growth into muscular targets; this was demonstrated by combined cholinesterase histochemistry for NMJ and immunohistochemistry for nerve fibers innervating NMJ with an axonal marker, protein gene product 9.5. Hollow conduits had similar index of NMJ innervation as autologous grafts; the values were higher than those of laminated conduits. Among the three groups, there were same patterns of differences in the cross-sectional area of muscle fibers and amplitudes of compound muscle action potential. These results indicate that hollow conduits were as efficient as autologous grafts to facilitate nerve regeneration, and provide a multidisciplinary approach to quantitatively evaluate muscular reinnervation after nerve injury.