Fabrication and characterization of 3D microtubular collagen scaffolds for peripheral nerve repair

Understanding the structure-function relationship in biomaterial constructs is critical in optimizing biological outcomes. For ensheathed structures such as peripheral nerve, engineering implantable tissue substitutes has been challenging. This is due to a unique geometry of thin-walled microtube arrays composed mostly of basement membrane. In this work, we propose a sacrificial templating method to create Matrigel scaffolds that resemble endogenous peripheral nerve. These paralleled microtube constructs possess high void space and membrane-like walls. Additionally, we investigated the effect of chemical crosslinking in altering the physical, mechanical, and biologic properties of Matrigel. Results show that both glutaraldehyde and genipin increased the modulus and failure stress of Matrigel while also improving degradation resistance. However, glutaraldehyde crosslinking induced some cytotoxicity whereas genipin showed good biocompatibility. PC-12 cells, Schwann cells, and primary chick dorsal root ganglia cultured onto microtube scaffolds demonstrated viability up to 10 days. Strong cellular alignment along the channels was observed in Schwann cells whereas neurite outgrowth in primary chick dorsal root ganglia was also biased along the major axis of the microtubes. This suggests that the microtubes may mediate cell orientation and axon pathfinding. This proof of concept study provides a tunable workflow that may be adapted to other collagen types.