31. Vasculogenic Gene Delivery Via Tissue Nanotransfection Enhances Functional Outcomes After Nerve Injury

PURPOSE: Segmental nerve defects are often repaired using autografts or acellular nerve allografts (ANAs). Achieving vascularization within nerve grafts is key for cellular survival, especially in grafts with large diameters and long lengths. In this study, we investigated vasculogenic gene delivery using tissue nano-transfection (TNT), following nerve transection, to support axonal regeneration by promoting new vasculature formation. METHODS: We used TNT to deliver a vasculogenic reprogramming gene cocktail including Etv2, Foxc2, and Fli1 (EFF) to the transected nerve at the coaptation site with either isografts or ANAs. Eight-week-old C57BL/6 mice received either a 1cm isograft or ANA to the right sciatic nerves. The study groups were control (sham surgery), cut without repair, isograft or ANA alone, isograft or ANA with sham TNT (empty plasmids), and isograft or ANA with EFF transfection. Functional assessments included sciatic functional index (SFI), compound muscle action potential (CMAP), motor unit number estimation (MUNE), twitch and tetanic force, and grip force were evaluated biweekly for 20 weeks. The mice were followed up to 13 weeks for the isograft group and 20 weeks for the ANA (until the outcomes plateaued). RESULTS: Vasculogenic transfection in isografts led to increased grip force, with statistical significance achieved at weeks 8 and 13. The EFF transfected isografts also demonstrated higher twitch and tetanic forces compared to the graft-only and sham transfection groups at weeks 10 and 13. In the ANA grafts, twitch force increased with EFF transfection at weeks 8 and 16. Similarly, EFF transfection significantly increased tetanic muscle force from week 8, with effects sustained through week 20. Grip force and CMAP were comparable between groups for ANA grafts. Histological assessment is ongoing to determine vascular changes among groups. CONCLUSION: Our study demonstrates that nanotransfection enhances nerve regeneration and functional muscle outcomes in nerve grafts, with earlier and more pronounced benefits observed in isografts compared to acellular nerve grafts.