Epidermal neural crest stem cells and their use in mouse models of spinal cord injury.

Epidermal neural crest stem cell (EPI-NCSC) grafts cause a significant improvement in sensory connectivity and touch perception in the contused mouse spinal cord. EPI-NCSC are derived from the embryonic neural crest but reside in a postnatal location, the bulge of hair follicles. Both mouse and human EPI-NCSC are multipotent adult stem cells capable of generating all major neural crest derivatives. EPI-NCSC of mouse and human origin express the neural crest stem cell molecular signature, genes that were initially used to create induced pluripotent stem (iPS) cells, and other neural crest and global stem cell genes. Due to their origin in the neural folds and because they share a higher order stem cell, neural crest cells, and thus EPI-NCSC, are closely related to neural tube stem cells. This close ontological relationship with the spinal cord makes EPI-NCSC attractive candidates for cell-based therapy in spinal cord injury. In two different contusion models of spinal cord injury, we have shown that EPI-NCSC integrate into the murine spinal cord tissue and that subsets differentiate into GABAergic neurons and myelinating oligodendrocytes. Intraspinal EPI-NCSC do not form tumours. In the presence of EPI-NCSC grafts, but not in control animals, there is a 24% improvement of sensory connectivity and a substantial improvement in touch perception. Unilateral transplants leading to bilateral functional improvements suggest that underlying mechanisms include diffusible molecules. EPI-NCSC indeed express genes that encode neurotrophins, other trophic factors, angiogenic factors and metalloproteases. Intraspinal EPI-NCSC thus have multiple effects in the contused spinal cord, the sum of which can explain the observed functional improvements.