Intramedullary Neural Stem Cell Transplantation in Spinal Cord Injury: Timing, Targets, and Techniques.

Spinal cord injury remains one of the most challenging neurological disorders due to limited intrinsic regeneration. Neural stem cell (NSC) transplantation offers a promising strategy for restoring neural circuitry and functional recovery. Among delivery methods, direct intramedullary transplantation provides the most localized graft placement and has shown encouraging safety and efficacy in early clinical trials. This review summarizes current evidence and technical considerations for intramedullary NSC transplantation. Key factors influencing outcomes include timing after injury, cell source, surgical approach, and host microenvironment. Advances in microsurgical delivery techniques and biomaterial scaffolds have improved graft survival and integration while minimizing procedure-related risks. Clinical data demonstrate that intramedullary NSC transplantation is feasible and generally safe, with early signals of motor improvement. Nevertheless, challenges remain in achieving consistent cell engraftment and long-term functional gains. Future work should focus on refining transplantation parameters, establishing standardized surgical protocols, and conducting multicenter trials with long-term follow-up to confirm clinical efficacy. By integrating current findings, this review provides a concise overview of surgical evolution and translational progress, highlighting intramedullary NSC transplantation as a key frontier in regenerative spinal surgery.