Objective     To evaluate the effects of glial cell line-derived neurotrophic factor (GDNF) gene-activated matrix (GAM) in bridging rat sciatic nerve defect.      Methods     The peripheral nerve extracellular matrix was harvested by chemical extraction. GDNF gene-activated matrix was comprised of the extracellular matrix and plasmids encoding GDNF. Ninety adult Wistar rats were randomly divided into three groups: group A (GDNF GAM conduits)

group B ( extracellular matrix conduits)

group C (autografts). At the end of 12 weeks

rats from each group were subjected to walking tract analysis

electrophysiological and histomorphological studies.      Results     GDNF DNA could be retained in GAM

promoting transgene expression in the sciatic nerve

in GAM

and more importantly

in axotomized neurons in spinal cord for 12 weeks. The number of regenerated axons for the GAM grafts in the distal sciatic nerve was lower than that for autografts (2 117±294 vs 2 474±297) at 12 weeks. The sciatic nerve function index for the GAM grafts was lower than that for autografts [(30.92±2.98)% vs (26.27±2.71) %] at 12 weeks.      Conclusion     GDNF GAM may be a promising alternative to autografts for repair of rat sciatic nerve.