The in vitro plasticity of hair follicle dermal and mesenchymal stem cells

Abstract

Stem cells from the hair follicle are an easily accessible population of cells that have a broad in vitro developmental capabilities and potential for autologous replacement of damaged adult tissue. The bulge region and follicle dermis play key roles in hair follicle development, stem cells of the bulge region are of epithelial origin, whereas dermal components of the hair follicle are of mesenchymal origin. Here we have compared the characteristics of rat clonal stem cell lines derived from both the hair follicle dermal sheath and dermal papilla with rat bone marrow-derived primary mesenchymal stem cells. The cell types were compared in terms of their morphology, proliferation, expression of intracellular and cell surface antigens and differentiation potential into bone and fat. The evidence presented here suggests that clonally derived stem cells from the follicle dermis posses some homologies with mesenchymal stem cells derived from bone marrow. Hence the hair follicle represents a potential niche for a mesenchymal-like population of stem cells. Both mesenchymal stem cells from bone marrow and stem cells from the follicle under specific in vitro conditions produce neural-like phenotypes. Here the two cell types were grown under conditions used in the culture of neural stem cells and formed aggregates that expressed the neural stem cell marker nestin. The effect of soluble factors produced by these aggregates on the development of neural progenitor cell populations was determined using aggregate conditioned media. The conditioned media induced process elaboration and differentiation towards the astrocytic lineage in a subpopulation of neural progenitors. Differential expression of antigens, loss of fat differentiation potential and extended proliferation capabilities were observed in the dermal clones. This aberrant behaviour could be attributable to transformation after extensive expansion in vitro, which has been demonstrated by their abnormal karyotype.