GDNF-loaded composite microspheres enhanced porous-oriented conduits for peripheral nerve regeneration

Peripheral nerve injuries, which can lead to nerve transection or long-segment defects, remain a challenging medical issue. Combining nerve guidance conduits (NGCs) with the delivery of neurotrophic factors is a promising therapeutic approach for peripheral nerve defects. In this study, oriented porous nerve conduits were fabricated by electrospinning a poly(lactic- co -glycolic acid) (PLGA) sheath around a chitosan–collagen (CH–CO) core at a 1:1 mass ratio. Separately, GDNF-loaded composite microspheres (CP-MSs) composed of chitosan methacryloyl and PLGA were produced via microfluidic technology. The CH-CO (1:1)/PLGA conduits that were produced exhibited optimal porosity, degradation properties, and mechanical stability, demonstrating excellent biocompatibility with PC12 and RSC96 cells in vitro. The CP-MSs, optimized for size and dispersion at specific aqueous and oil flow rates, had a diameter of 73.2 ± 4.5 μm, with an encapsulation efficiency and drug loading of 81.2 ± 1.9% and 0.84 ± 0.11%, respectively. In vitro studies showed that CP-MSs were biocompatible and released GDNF sustainably, promoting PC12 cell differentiation and maintaining biological activity for 6 weeks. Histological and functional assessments of nerve regeneration confirmed that CP-MSs combined with the CH-CO (1:1)/PLGA conduits significantly enhanced peripheral nerve regeneration, as evidenced by axonal myelination, longitudinal axonal growth, and functional recovery. This study demonstrated the feasibility of CP-MSs with oriented multichannel CH-CO1:1/PLGA conduits for effective nerve defect repair, indicating its promising application in peripheral nerve regeneration.