Epidermal Neural Crest Stem Cells (EPI-NCSC) and Pluripotency

Abstract

This article serves three purposes. We summarize current knowledge of the origin and characteristics of EPI-NCSC, review their application in a mouse model of spinal cord injury, and we present new data that highlight aspects of pluripotency of EPI-NCSC. EPI-NCSC are multipotent stem cells, which are derived from the embryonic neural crest and are located in the bulge of hair follicles. EPI-NCSC can undergo self-renewal and they are able to generate all major neural crest derivatives, including neurons, nerve supporting cells, smooth muscle cells, bone/cartilage cells and melanocytes. Despite their ectodermal origin, neural crest cells can also generate cell types that typically are derived from mesoderm. We were therefore interested in exploring aspects of EPI-NCSC pluripotency. We here show that EPI-NCSC can fuse with adult skeletal muscle fibers and that incorporated EPI-NCSC nuclei are functional. Furthermore, we show that adult skeletal muscle represents an environment conducive to long-term survival of neurogenic EPI-NCSC. Genes used to create induced pluripotent stem (iPS) cells are present in our EPI-NCSC longSAGE gene expression library. Here we have corroborated this notion by real-time PCR. Our results show similarities in the expression of Myc, Klf4, Sox2 and Lin28 genes between EPI-NCSC and embryonic stem cells (ESC). In contrast there were major differences in Nanog and Pou5f1 (Oct-4) expression levels between EPI-NCSC and ESC, possibly explaining why EPI-NCSC are not tumorigenic. Overall, as embryonic remnants in an adult location EPI-NCSC show several attractive characteristics for future cell replacement therapy and/or biomedical engineering: Due to their ability to migrate, EPI-NCSC can be isolated as a highly pure population of multipotent stem cells by minimally-invasive procedures. The cells can be expanded in vitro into millions of stem cells/progenitors and they share some characteristics with pluripotent stem cells without being tumorigenic. Since the patients' own EPI-NCSC could be used for autologous transplantation, this would avoid graft rejection.