UV-Casting on Methacrylated PCL for the Production of a Peripheral Nerve Implant Containing an Array of Porous Aligned Microchannels

Peripheral nerves are basic communication structures guiding motor and sensory information from the central nervous system to receptor units. Severed peripheral nerve injuries represent a large clinical problem with relevant challenges to successful synthetic nerve repair scaffolds as substitutes to autologous nerve grafting. Numerous studies reported the use of hollow tubes made of synthetic polymers sutured between severed nerve stumps to promote nerve regeneration while providing protection for external factors, such as scar tissue formation and inflammation. Few approaches have described the potential use of a lumen structure comprised of microchannels or microfibers to provide axon growth avoiding misdirection and fostering proper healing. Here, we report the use of a 3D porous microchannel-based structure made of a photocurable methacrylated polycaprolactone, whose mechanical properties are comparable to native nerves. The neuro-regenerative properties of the polymer were assessed in vitro, prior to the implantation of the 3D porous structure, in a 6-mm rat sciatic nerve gap injury. The manufactured implants were biocompatible and able to be resorbed by the host's body at a suitable rate, allowing the complete healing of the nerve. The innovative design of the highly porous structure with the axon guiding microchannels, along with the observation of myelinated axons and Schwann cells in the in vivo tests, led to a significant progress towards the standardized use of synthetic 3D multichannel-based structures in peripheral nerve surgery.

High Throughput Manufacturing of Bio-Resorbable Micro-Porous Scaffolds Made of Poly(L-lactide-co-ε-caprolactone) by Micro-Extrusion for Soft Tissue Engineering Applications

Porous scaffolds made of elastomeric materials are of great interest for soft tissue engineering. Poly(L-lactide-co-ε-caprolactone) (PLCL) is a bio-resorbable elastomeric copolymer with tailorable properties, which make this material an appropriate candidate to be used as scaffold for vascular, tendon, and nerve healing applications. Here, extrusion was applied to produce porous scaffolds of PLCL, using NaCl particles as a leachable agent. The effects of the particle proportion and size on leaching performance, dimensional stability, mechanical properties, and ageing of the scaffolds were analyzed. The efficiency of the particle leaching and scaffold swelling when wet were observed to be dependent on the porogenerator proportion, while the secant moduli and ultimate tensile strengths were dependent on the pore size. Porosity, swelling, and mechanical properties of the extruded scaffolds were tailorable, varying with the proportion and size of porogenerator particles and showed similar values to human soft tissues like nerves and veins (E = 7-15 MPa, σu = 7 MPa). Up to 300-mm length micro-porous PLCL tube with 400-µm thickness wall was extruded, proving extrusion as a high-throughput manufacturing process to produce tubular elastomeric bio-resorbable porous scaffolds of unrestricted length with tunable mechanical properties.