The mechanics of scaling-up multichannel scaffold technology for clinical nerve repair

Peripheral nerve injury remains a large clinical problem, with challenges to the successful translation of nerve repair devices. One promising technology is the multichannel scaffold, a conduit Incorporating arrays of linear microchannels, which has high open lumen volume to guide regenerating nerves toward distal targets. To maximize open lumen volume, and scale-up scaffolds for translation, this study explored how mechanical properties were affected by 1) material choice (poly(lactide co-glycolide) (PLGA) and poly(caprolactone) (PCL)), 2) microstructure (porous and non-porous), and 3) channel architecture (200 mu m and 300 mu m diameter). After testing in transverse compression and bending, it was noted that introduction of porosity and increasing microchannel diameter increased scaffold compliance from 0.05 +/- 0.1-2.75 +/- 0.8 mm/N. Porosity also increased flexibility and eliminated kinking, which could potentially damage regenerating nerves. Material choice determined both scaffold deformation and mechanics. Porous PLGA scaffolds were stiffer than porous PCL, with greater deformation. Having demonstrated stability and flexibility, porous PCL multichannel scaffolds were scaled from 1.5 mm to 10 mm in diameter, a range applicable to the clinic. Even at 10 mm in diameter, the linear structure, high open lumen volume and compliance were retained. This demonstrates significant progress towards translation and brings multichannel technology closer to the clinic.