Amnion Wrapped Nerve - Muscle Composite Bridge Repair Of Rat Sciatic Nerve Defects

OBJECTIVE: To explore the possibility of repairing the sciatic nerve defect by using a composite nerve-muscle (NM) autograft in rat.METHODS: 54 Wistar rats (180-220g) were divided into three groups randomly: The composite nerve-muscle (NM) autograft group (Group A, n=18), Nerve autografts (Group B, n=18), denatured skeletal muscles graft (Group C, n=18). The right sciatic nerve was exposed in the mid-thigh region and a segment removed, a final 10mm-long defect produced. In group A, the distal stump was split longitudinally for 10 mm, produced two limbs. One of this two limbs was removed by 10mm and interposed between the other limb and the proximal stump, the other side was bridged with a piece of denatured skeletal muscle. Nerve autografts (Group B) and denatured skeletal muscles graft (Group C) as control. All grafts wrapped with HAMM (Human Amnion Matrix Membrane). Evaluations at different time (8, 16, 24weeks postoperatively) included general observation, retrograde tracing, wet weight of the tibialis anterior muscle, axonal counting, and histological examination(neurofilanients immunohistochemistry, semi-thin sections and morphometry). Data were dealt with statistics.RESULTS: Muscles atrophy at 6-9 weeks postoperatively in each group. Only a few Fast Blue labeled cells can be found in dorsal root ganglia (DRG) and ventral horn (L3~L6) at 8 weeks; In group A and B, there were more labeled cells appeared both in DRG and spinal cord sections than that of group C at 16 week. At 24 weeks, both group A and B histological examination showed that the regenerated axons in the bridge segments more tidy and dense than that of group C, and HAMM absorbed completely; Group A and B have significantly high degree of restoration of tibialis anterior muscle wet weight than that of group C, also greater density of the myelinated axons, mean diameter and thickness of myelin sheath in the semi-thin section (P<0.05); But, no statistics difference between group A and B in wet weight of tibialisanterior muscle and density of the myelinated axons (P> 0.05).CONCLUSION: The results indicate that the composite nerve-muscle autograft is similar to autologous nerve graft and superior to denatured skeletal muscles autograft enveloped in HAMM in repairing rat sciatic nerve defects. It is necessary to research further more.