Fabrication of the microgrooved/microporous polylactide substrates as peripheral nerve conduits and in vivo evaluation.

An innovative technique combining phase transition and microprinting in one step was applied to fabricate the nerve conduits used in peripheral nerve regeneration. The asymmetric microporosity served to generate asymmetric permeability, and the surface microgrooves were introduced to achieve cell alignment in vitro. The symmetric/asymmetric porous poly(D,L-lactide) (PLA) substrates with microgrooves on the surface were tested for their ability to repair 10 mm sciatic nerve transection defects in rats. The in vivo results showed that porous PLA conduits maintained a stable supporting structure during the entire regeneration process. The myelin sheaths of the regenerated nerve in asymmetric conduits were thicker than in symmetric groups at 4 weeks. Moreover, the regenerated nerves in the asymmetric conduits with surface microgrooves had the highest degree of myelination at 4 weeks and the most number of vessels at 6 weeks. The walking track analysis also implied that the asymmetric conduits with surface microgrooves had the highest degree of functional recovery. Based on the study, the combination of microgrooves and asymmetric microporous structure could be employed in the design of nerve conduits for peripheral nerve regeneration in the future.