A collagen microchannel scaffold carrying paclitaxel-liposomes induces neuronal differentiation of neural stem cells through Wnt/β-catenin signaling for spinal cord injury repair

Neural stem cells (NSCs) show potential for spinal cord injury (SCI) repair. However, the current challenge is to direct their differentiation into neurons in the lesion site. It has been demonstrated that transplanted NSCs primarily differentiated into astrocytes rather than neurons due to the adverse microenvironment. It was reported that microtubule-stabilizing agent paclitaxel (PTX) was able to reduce scarring and enhance intrinsic axon regeneration after SCI. In this study, the effect of PTX on NSC differentiation was studied. It was demonstrated for the first time that PTX could rescue myelin-inhibited neuronal differentiation of NSCs, and induced a higher neuronal differentiation as compared with that in normal microenvironment. Enhanced neuronal differentiation in normal microenvironment further validated that PTX was capable of inducing intrinsic neuronal differentiation of NSCs. Furthermore, a functional collagen scaffold was developed by loading PTX-encapsulated liposomes into a collagen microchannel scaffold, leading to a prolonged sustained release of PTX. When NSC-laden functional collagen scaffold was implanted into T8 complete transection site of rat spinal cord, the scaffold provided an instructive microenvironment for neuronal differentiation of NSCs, motor and sensory neuron regeneration, and axon extension. The neural regeneration eventually led to improvement in motor evoked potential and hindlimb locomotion recovery. Moreover, mRNA-Seq and western blotting results revealed that PTX-triggered neuronal differentiation occurred through Wnt/beta-catenin signaling pathway. Together, the collagen microchannel scaffold in combination with sustained release of therapeutic agents for inducing neuronal differentiation of NSCs is promising for SCI repair.