Reverse engineering of an anatomically equivalent nerve conduit.

Reconstruction of peripheral nervous tissue remains challenging in critical-sized defects due to the lack of Büngner bands from the proximal to the distal nerve ends. Conventional nerve guides fail to bridge the large-sized defect owing to the formation of a thin fibrin cable. Hence, in the present study, an attempt was made to reverse engineer the intricate epi-, peri- and endo-neurial tissues using Fused Deposition Modeling based 3D printing. Bovine serum albumin protein nanoflowers (NF) exhibiting Viburnum opulus 'Roseum' morphology were ingrained into 3D printed constructs without affecting its secondary structure to enhance the axonal guidance from proximal to distal ends of denuded nerve ends. Scanning electron micrographs confirmed the uniform distribution of protein NF in 3D printed constructs. The PC-12 cells cultured on protein ingrained 3D printed scaffolds demonstrated cytocompatibility, improved cell adhesion and extended neuronal projections with significantly higher intensities of NF-200 and tubulin expressions. Further suture-free fixation designed in the current 3D printed construct aids facile implantation of printed conduits to the transected nerve ends. Hence the protein ingrained 3D printed construct would be a promising substitute to treat longer peripheral nerve defects as its structural equivalence of endo- and perineurial organization along with the ingrained protein NF promote the neuronal extension towards the distal ends by minimizing axonal dispersion.