3D-PRINTED MICROSCAFFOLDS PROMOTE MORPHOLOGICAL AND FUNCTIONAL REGENERATION FOLLOWING PERIPHERAL NERVE INJURY

Peripheral nerve injury (PNI) often leads to motor and sensory deficits due to limited or misdirected axonal regeneration. Here we evaluated sciatic nerve repair after PNI using a novel 3D-printed microscaffold. Hollow scaffolds with hexagonal tunnels (50 µm across) were fabricated by two-photon photopolymerization, inserted into a silicone conduit, and implanted into a 6 mm gap in the sciatic nerve of Wistar rats.
SFI and Hargreaves’s test showed significantly better functional recovery in animals with scaffolds by the fifth month after implantation and faster sensory improvement compared to the autografts and empty silicon conduits. The scaffolds were mainly preserved in the recipient's tissue, although they had some cracks that could affect regeneration. Tissue near the proximal end of the scaffolds mostly extended to the walls of the silicone conduit, showing an unfavourable pattern with a partial preservation of the original organization. Immunohistochemistry of the majority of scaffolds showed that 67% of the tunnels at the proximal side have ingrown tissue mostly concentrated along the tunnel walls; the percentage of full tunnels decreases to 33% distally. Tissue was composed of aligned, rostrocaudally oriented myelinated and unmyelinated axons and blood vessels. The absence of changes in axons density distally coupled with a decrease in axons diameters indicated an active axonal sprouting.
Our findings demonstrate that 3D-oriented hollow scaffolds provide a favorable microenvironment for both morphological and functional recovery following PNI compared to other treatment approaches.
This work was funded by NRFU grant 2021.01/0328 and NANU grant 0124U001557.