<scp>GelMA</scp> Hydrogel Encapsulating <scp>iPSC</scp> ‐Derived Human Spinal Cord Organoids Enhances Neural Regeneration and Restores Motor Function in Rat Spinal Cord Injury

Spinal cord injury (SCI) severely compromises neural regeneration due to limited intrinsic repair capacity. Combining induced pluripotent stem cell (iPSC)-derived organoids with biomaterial scaffolds offers a promising regenerative strategy. This study investigated the therapeutic potential of human spinal cord organoids (hSCOs) encapsulated within gelatin methacryloyl (GelMA) hydrogel for SCI repair. hSCOs were generated from iPSCs via stage-specific patterning (dorsoventral inhibition followed by retinoic acid/SAG-induced motor neuron specification) and encapsulated in GelMA hydrogel. The therapeutic efficacy of hSCOs/GelMA composites was evaluated in a rat T10 contusion SCI model (n = 6/group: Sham, SCI, GelMA-only, GelMA+hSCOs). Functional recovery was assessed weekly for 4 weeks using Basso-Beattie-Bresnahan (BBB) locomotor scores and inclined plane tests. Histological (H&E, Nissl) and immunofluorescence analyses (Tuj1, GFAP, NF200, CD68) quantified tissue repair, neuronal regeneration, astrogliosis, and neuroinflammation at the lesion site. hSCOs expressed key spinal cord markers (OLIG2, NKX6.1, Tuj1, Islet1) and maintained high viability within GelMA hydrogels. Implantation of GelMA+hSCOs composites significantly enhanced functional recovery (improved BBB scores and inclination angles) and reduced lesion volume compared to both SCI and GelMA-only controls. Immunofluorescence revealed that GelMA+hSCOs treatment promoted neuronal integration (increased density of Tuj1⁺ neurons and NF200⁺ neurofilaments), attenuated astrogliosis (reduced GFAP⁺ scarring), and suppressed neuroinflammation (decreased CD68⁺ macrophages) at the injury epicenter relative to control groups. The integration of iPSC-derived hSCOs with GelMA hydrogel significantly promotes structural and functional recovery after SCI by facilitating neuronal survival and integration, mitigating glial scar formation, and modulating the inflammatory response. This combinatorial organoid-hydrogel approach demonstrates substantial translational potential for neural repair strategies.