Dermal cell populations show variable competence in epidermal cell support: stimulatory effects of hair papilla cells.

A study was made of the comparative abilities of adult rat vibrissa dermal papilla cells, skin fibroblasts and 3T3 cells to support the initial attachment and subsequent growth and division of directly associated newborn rat skin basal epidermal cells. These associations were made under sub-optimal conditions; that is, in the absence of specific epidermal growth-promoting supplements, in order to assess more accurately the epidermal sustaining capacities of each dermal support. Analysis of epidermal cell counts and close photographic scrutiny revealed that low-passage dermal papilla cells, closely followed by transformed dermal papilla cells, were conducive to the successful attachment and subsequent proliferation of epidermal cell populations under three different experimental protocols. In contrast, skin fibroblasts did not support epidermal cell growth under any circumstances. These findings are particularly interesting in that they constitute a rare in vitro example of epidermal cells that are not only supported, but also encouraged to proliferate, by an actively dividing adult skin-derived dermal cell population.