Islation of Neural Crest-Derived Pluripotent Stem Cells in Adult Dental Tissue

         D. Pelaez, C.Y. CH Huang, HS Cheung (Miami VA Healthcare System, Miami, FL)

Cellular potency, or the potential for a cell to differentiate down various tissue lineages, is the defining characteristic as to the viability of the cell source for a given application. With the establishment of ESC, the idea of utilizing pluripotent cell sources for regenerative medical applications was introduced as a promising alternative to traditional medical practices. However, there are ethical dilemmas as well as immunological concerns arising from the use of ESC in clinical settings. The advent of induced pluripotent stem cells (iPSCs) attempted to circumvent both of these issues and brought the concept of patient-specific pluripotent stem cell attainment to the forefront of the field. This iPSC technology is still in its early stages, the scientific community is trying to decipher the mechanisms underlying the induction of pluripotency and overcome the aberrant epigenetic changes arising from the implementation of the technique. Nevertheless, the potential of obtaining pluripotent stem cells from adult tissues is of significant importance and remains as the ultimate goal in overcoming the limitations presently found with other post-natal stem cell populations.

Identification and isolation of pluripotent stem cells in adult tissues represents an important advancement in the fields of stem cell biology and regenerative medicine. Work has been performed on the identification of biomarkers that can isolate stem cells residing in neural crest-derived adult tissues. The neural crest is an excellent model in stem cell biology as cells from it migrate extensively and contribute to the formation of diverse tissues in the body during organogenesis. Migration of these cells is modulated in part by gap junction communication amongst the cell sheets. Here we present a study in which selection of connexin 43 (Cx43) expressing cells from human adult periodontal ligament yields a novel pluripotent stem cell population. Cx43⁺ periodontal ligament stem cells express pluripotency-associated transcription factors OCT4, Nanog, and Sox2, as well as neural crest-specific markers Sox10, p75, and Nestin. When injected in-vivo into an immunodeficient mouse model, these cells were capable of generating teratomas with tissues from the three embryological germ layers: endoderm, mesoderm, and ectoderm. Furthermore, the cells formed mature structures of tissues normally arising from the neural crest during embryogenesis such as eccrine sweat glands of the human skin, muscle, neuronal tissues, cartilage, and bone. Immunohistochemical analysis confirmed the human origin of the neoplastic cells as well as the ectodermal and endodermal nature of some of the structures found in the tumors. These results suggest that Cx43 may be used as a biomarker to select and isolate remnant neural crest pluripotent stem cells from adult human tissues arising from this embryological structure. The isolation of these cells through routine medical procedures such as wisdom teeth extraction further enhances their applicability to the regenerative medicine field.