Extensive restoration of forelimb function in primates with spinal cord injury by neural stem cell transplantation.

Grafts of human embryonic stem cell-derived spinal cord neural stem cells (H9-scNSCs) restored forelimb function after spinal cord injury in primates. Hemisected animals improved 9.2-fold on a skilled hand task versus lesioned controls (P = 2.5 × 10-27), reaching 53.4 ± 19.2% fine object retrieval success, and hemicontused animals improved 2.9-fold (P = 6.3 × 10-8). Grafts extended axons up to 39 mm below the injury and formed synapses with host circuits, with recovery correlating with rehabilitation effort.