Adult Human Dental Pulp Stem Cells Differentiate Towards Functionally Active Neurons Under Appropriate Environmental Cues

¹ The Australian Research Council, Centre for the Molecular Genetics of Development, University of Adelaide, Adelaide, 5005, SA, Australia.; School of Molecular and Biomedical Science (Genetics), University of Adelaide, Adelaide, 5005, SA, Australia.; Mesenchymal Stem Cell Group, Division of Haematology, Institute of Medical and Veterinary Science, Hanson Institute/Adelaide University, Adelaide, 5000, SA, Australia.
² School of Molecular and Biomedical Science (Physiology), University of Adelaide, Adelaide, 5005, SA, Australia.
³ School of Dentistry, University of Southern California, Los Angeles, 90089-0641, CA, USA.
⁴ The Australian Research Council, Centre for the Molecular Genetics of Development, University of Adelaide, Adelaide, 5005, SA, Australia.; School of Molecular and Biomedical Science (Genetics), University of Adelaide, Adelaide, 5005, SA, Australia.
⁵ Mesenchymal Stem Cell Group, Division of Haematology, Institute of Medical and Veterinary Science, Hanson Institute/Adelaide University, Adelaide, 5000, SA, Australia.

^* To whom correspondence should be addressed. E-mail: stan.gronthos{at}imvs.sa.gov.au.

	Abstract

Human adult dental pulp stem cells (DPSC) reside within the perivascular niche of dental pulp and are thought to originate from migrating cranial neural crest (CNC) cells. During embryonic development, CNC cells differentiate into a wide variety of cell types including neurons of the peripheral nervous system. Previously, we have demonstrated that DPSC derived from adult human third molar teeth differentiate into cell types reminiscent of CNC embryonic ontology. We hypothesized that DPSC exposed to the appropriate environmental cues would differentiate into functionally active neurons. The data demonstrated that ex vivo expanded human adult DPSC responded to neuronal inductive conditions both in vitro and in vivo. Human adult DPSC, but not human foreskin fibroblasts (HFF) acquired a neuronal morphology, and expressed neuronal specific markers at both the gene and protein levels. Culture expanded DPSC also exhibited the capacity to produce a sodium current consistent with functional neuronal cells when exposed to neuronal inductive media. Furthermore, the response of human DPSC and HFF to endogenous neuronal environmental cues was determined in vivo using an avian xeno-transplantation assay. DPSC expressed neuronal markers and acquired a neuronal morphology following transplantation into the mesencephalon of embryonic day two chicken embryo, while HFF maintained a thin spindle fibroblastic morphology. We propose that adult human DPSC provide a readily accessible source of exogenous stem/precursor cells which have the potential for use in cell therapeutic paradigms to treat neurological disease.