A Biodegradable, Tacrolimus-releasing Nerve Wrap Promotes Peripheral Nerve Regeneration

Axonal regeneration following nerve repair is slow and often incomplete, resulting in poor functional recovery and sometimes lifelong disability. Yet, there are no FDA-approved therapies available to promote nerve regeneration. Tacrolimus accelerates axonal regeneration, but systemic side-effects presently outweigh its potential benefits for peripheral nerve surgery. We have developed a biodegradable drug delivery system for the sustained local release of tacrolimus at the nerve repair site, with suitable properties for large-scale manufacturing and clinical application, aiming to promote axonal regeneration and functional recovery with minimal systemic drug exposure. Tacrolimus is encapsulated in polycarbonate-urethane nanofibers and electrospun to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 days. Size and drug loading are adjustable for applications in small and large caliber nerves, and the wrap degrades within 120 days into biocompatible byproducts. Tacrolimus released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while systemic drug exposure is reduced by 80% compared to systemic delivery. Given its surgical suitability and preclinical efficacy and safety, this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.