PEOT/PBT Guides Enhance Nerve Regeneration in Long Gap Defects

Development of new nerve guides is required for replacing autologous nerve grafts for the repair of long gap defects after nerve injury. A nerve guide comprised only of electrospun fibers able to bridge a critical (15 mm) nerve gap in a rat animal model is reported for the first time. The nerve conduits are made of poly(ethylene oxide terephthalate) and poly(butylene terephthalate) (PEOT/PBT), a biocompatible copolymer composed of alternating amorphous, hydrophilic poly(ethylene oxide terephthalate), and crystalline, hydrophobic poly(butylene terephthalate) segments. These guides show suitable mechanical properties, high porosity, and fibers aligned in the longitudinal axis of the guide. In vitro studies show that both neurites and Schwann cells exhibit growth alignment with PA fibers. In vivo studies reveal that, after rat sciatic nerve transection and repair with PEOT/PBT guides, axons grow occupying a larger area compared to silicone tubes. Moreover, after repair of limiting (10 mm) and critical (15 mm) nerve gaps, PEOT/PBT guides significantly increase the percentage of regenerated nerves, the number of regenerated myelinated axons, and improve motor, sensory, and autonomic reinnervation in both gaps. This nerve conduit design combines the properties of PEOT/PBT with electrospun structure, demonstrating that nerve regeneration through long gaps can be achieved through the design of instructive biomaterial constructs.