GDNF released from microspheres enhances nerve regeneration after delayed repair.

INTRODUCTION Delays in surgical repair following nerve transection produce progressively inferior motor nerve regeneration. Regeneration can be improved with delivery of exogenous growth factor. We developed a delivery system that could be applied at the nerve repair site to deliver growth factors locally to regenerating nerve. METHODS Poly(lactic-co-glycolic acid) microspheres containing glial-derived neurotrophic factor (GDNF) suspended within fibrin were developed into a delivery system for local application surrounding nerve at a repair site in an experimental rat model. RESULTS The system containing GDNF remained at the injury site for up to 2 weeks and improved motor nerve regeneration following chronic axotomy and denervation. CONCLUSIONS Based on the positive outcome of the delivery system, we plan to study the delivery system over longer time courses of release and nerve regeneration.