195. Evaluating the Location of Tissue Nanotransfection to Improve Nerve Regeneration

PURPOSE: Tissue nanotransfection (TNT) is a novel strategy for non-viral plasmid delivery that has been shown to increase vasogenesis and improve functional outcomes in a sciatic nerve crush model when delivered at the site of injury. This study examines the impact of location of delivery of TNT when applied either proximal or distal to the sciatic nerve injury. The goal is to determine the ideal location of TNT delivery in more severe injury models, such as sciatic nerve transection and repair. We hypothesize that delivery distal to the injury will improve nerve regeneration. METHODS: C57BL/6 mice (8-10 week-old) were randomized into four study groups (n = 10) including sham surgery, cut and repair, cut and repair with proximal TNT, and cut and repair with distal TNT. In cut and repair models, the sciatic nerve was transected 3mm proximal to the nerve trifurcation. TNT was used to deliver a vasculogenic reprogramming gene cocktail of Etv2, Foxc2, and Fli1 (EFF) to the injured nerve. In proximal and distal TNT groups, TNT was delivered 3mm proximal or distal to the site of transection, respectively. Four mice from each study group were sacrificed two weeks postoperatively for histology. The remaining mice in each group underwent functional assessments including compound muscle action potential (CMAP), motor unit number estimation (MUNE), twitch and tetanic force, and grip force for 14 weeks. RESULTS: Distal TNT led to an increased grip force, reaching significance at weeks 7, 10 and 14. Tetanic force was also increased in the distal TNT group, reaching significance at 7 weeks. Histologic evaluation of sciatic nerve samples is currently ongoing and is expected to be completed at the time of presentation. This analysis will include immunohistochemistry staining for NF100, CD31 and MBP in order to evaluate axon count, G-ratio, and vascularity. CONCLUSION: Our study demonstrates improved function recovery after a sciatic nerve transection injury when TNT is performed distal to the site of injury. Further histological analysis is ongoing to understand the cellular milieu involved.