Peripheral nerve growth within a hydrogel microchannel scaffold supported by a kink-resistant conduit.

Nerve repair in several mm-long nerve gaps often requires an interventional technology. Microchannel scaffolds have proven effective for bridging nerve gaps and guiding axons in the peripheral nervous system (PNS). Nonetheless, fabricating microchannel scaffolds at this length scale remains a challenge and/or is time consuming and cumbersome. In this work, a simple computer-aided microdrilling technique was used to fabricate 10 mm-long agarose scaffolds consisting of 300 µm-microchannels and 85 µm-thick walls in less than an hour. The agarose scaffolds alone, however, did not exhibit adequate stiffness and integrity to withstand the mechanical stresses during implantation and suturing. To provide mechanical support and enable suturing, poly caprolactone (PCL) conduits were fabricated and agarose scaffolds were placed inside. A modified salt-leaching technique was developed to introduce interconnected porosity in PCL conduits to allow for tuning of the mechanical properties such as elastic modulus and strain to failure. It was shown that the PCL conduits were effective in stabilizing the agarose scaffolds in 10 mm-long sciatic nerve gaps of rats for at least 8 weeks. Robust axon ingress and Schwann cell penetration were observed within the microchannel scaffolds without using growth factors.