Bioactive keratin-pectin methacrylate multifilament nerve conduits for functional regeneration across segmental nerve...

Repair of critical peripheral nerve injuries requires bioactive conduits that provide structural guidance while supporting cellular regeneration. Here, we engineered a biomimetic hydrogel conduit comprising methacrylated pectin (PecMA) functionalized with human hair-derived keratin to integrate fascicle-mimetic architecture with biochemical cues. Keratin was extracted using a urea-based reduction strategy and conjugated to PecMA via thiol-ene chemistry, yielding a dual-crosslinkable bioink. A custom multifilament extrusion platform enabled fabrication of aligned fascicle-like conduits. In vitro, cell-laden constructs demonstrated uniform cellular distribution, high viability, and enhanced neurite extension following keratin incorporation. PC12 neurite length increased from 6.28 ± 0.49 μm on day 1 to 64.77 ± 4.85 μm on day 14, while qRT-PCR revealed increased expression of neuronal (PRPH, TUBB3, NEFH) and Schwann cell/myelination-associated (PMP22, MBP, MPZ) genes compared with PecMA. In vivo, acellular Keratin-PecMA conduits were evaluated in a rat sciatic nerve defect model and demonstrated favourable biocompatibility, aligned axonal regeneration, and reduced fibrotic tissue infiltration. The Keratin-PecMA group showed progressive improvement in SFI, with foot-slip percentage decreasing from 32.5 ± 3.2% at week 2 to 15.0 ± 2.2% at week 8. At 8 weeks, SFI scores (-60.95 ± 2.68 vs. -57.73 ± 3.99), nerve fibre diameter (2.12 ± 0.12 vs. 2.11 ± 0.25 μm), and muscle-to-collagen ratio (3.21 ± 0.06 vs. 2.95 ± 0.25) were comparable between the Keratin-PecMA and autograft groups. Overall, these findings support Keratin-PecMA multifilament conduits as a promising biomimetic strategy for peripheral nerve regeneration.