Spinal cord transection repair occurs when Nestin+ cells differentiate into neurons within a taxol-collagen-enhanced microenvironment in mice

Previous studies have shown that taxol promotes axon regeneration in nerve repair, but fails to bridge the two ends of a completely transected spinal cord. Our prior in vitro research revealed that taxol, a microtubule-stabilizing agent, promotes neural stem cells (NSCs) differentiation into neurons while inhibiting astrocyte differentiation. In vivo studies further demonstrated that taxol-scaffold enhances functional recovery in animals with complete spinal cord injury (SCI). This study aims to directly validate the role of taxol-collagen in guiding NSCs to differentiate into neurons at the SCI lesion site and clarify its molecular mechanism.

This study is an interventional experimental research based on animal models. The research objects are 8-week-old Nestin-CreER:tdTomato transgenic mice, as well as endogenous NSCs and spinal cord tissues at the SCI site. A total of 30 mice were used, divided into a control group (15 mice, injected with collagen gel) and an intervention group (15 mice, injected with collagen gel containing 256 ng taxol). Five mice from each group were sampled for detection at 2, 4, and 8 weeks, respectively. Mice with qualified genotypes, successful model establishment, and positive red fluorescent protein (RFP) labeling were included, while those that did not meet these criteria were excluded. The outcomes included indicators related to NSC differentiation, microenvironment, neural circuit, molecules, and functions. GraphPad Prism 8 (Prism 8.4.3.686, CA, USA) was used for normality test and unpaired t-test (α = 0.05).

Taxol-collagen was found to guide NSCs toward neuronal differentiation by remodeling the SCI microenvironment: at 2 weeks post-SCI, the co-localization of its RFP-labeled NSCs with doublecortin was higher versus control; at 4 weeks, the co-localization of RFP-labeled NSCs with beta-tubulin III was more versus control; at 8 weeks, chondroitin sulfate proteoglycan deposition at the injury site was less. It formed a nerve bridge to reconnect the rostral-caudal injury ends and improved functional recovery in animals with complete SCI, as at 8 weeks postsurgery, motor evoked potentials latency was shortened and amplitude difference increased compared with the control group (n > 6, all p < 0.05). RNA-sequencing further elucidated the molecular mechanism, showing 992 upregulated and 220 downregulated genes in the taxol-collagen group; quantitative polymerase chain reaction validated related genes (e.g., Hes1, p < 0.05); Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated those genes were enriched in Wingless/Int-1 and mechanistic target of rapamycin pathways.

These findings provide theoretical support for the clinical application of taxol-collagen in SCI treatment. By promoting neuronal differentiation of NSCs at the injury site and elucidating the underlying molecular mechanism, this study may facilitate the development of novel SCI therapeutic strategies.