Stimulation of human scalp papilla cells by epithelial cells.

Evidence for the growth stimulatory properties of human keratinocyte-derived conditioned medium on human scalp dermal papilla cells and a mouse fibroblast cell line (Balb/c 3T3) is presented. There was no mitogenic effect on human keratinocytes. This conditioned medium induced a 2-5-fold increase in mitogenic activity in papilla cells relative to sham-conditioned medium as measured by 3H-thymidine incorporation. The papilla cell growth-stimulating activity of the conditioned medium was sensitive to heat, and from size exclusion the molecular weight was greater than 3000 Da.