Biomaterials integrating guidance cues have been developed to modulate microenvironments in situ, demonstrating potential for enhancing neurite growth and motor recovery. However, constructing a dynamically degradable microenvironment that matches the growth kinetics of regenerated nerves remains a challenge in developing nerve guidance conduits for long-distance nerve gaps. To address this problem, we used liquid electrospinning to fabricate a sequentially degradable scaffold consisting of a functionalized, aligned chitosan hydrogel and an aligned fibrin hydrogel, referred to as a functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel scaffold. The scaffold was further functionalized with bioactive peptides derived from vascular endothelial growth factor and brain-derived neurotrophic factor to provide angiogenic and neurotrophic stimuli for nerve growth. Material characterization revealed a hierarchical, aligned nanofibrous architecture of functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel and a prolonged degradation period of aligned chitosan fibers. Functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel promoted directional neurite outgrowth of dorsal root ganglion and migration of Schwann cells along the long axis, mimicking the native nerve fascicular microstructure in vitro. To evaluate its efficacy for nerve regeneration across long peripheral nerve defects, functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel was used to fill chitosan nerve conduits, which were then implanted to bridge a 15-mm defect in the sciatic nerve in rats. At 12 weeks postoperatively, the functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel group exhibited significantly increased regenerated axon density and myelin maturity compared with control groups, with motor function recovery and target muscle reinnervation comparable to those in the Autograft group. The sequentially degradable scaffold, functionalized, aligned chitosan hydrogel/aligned fibrin hydrogel functionalized with neurovascular-supportive peptides to enhance nerve regeneration, provided sustained topographical guidance through the slower-degrading chitosan fiber component aligned chitosan hydrogel, whereas the fast-degrading fibrin component aligned fiber enabled early cell infiltration. Combining structural alignment with bioactive peptide conjugation in a sequentially degradable hydrogel creates a pro-regenerative microenvironment in vitro and in vivo, offering a strategy to overcome the limitations of current nerve guidance conduits.
Fang et al. (Thu,) studied this question.