CULTURED DERMAL PAPILLA CELLS OF THE RAT VIBRISSA FOLLICLE - PROLIFERATIVE ACTIVITY, ADHESION PROPERTIES AND REORGANIZATION OF THE EXTRACELLULAR-MATRIX IN-VITRO

The dermal papilla of the mammalian hair follicle plays an important r ole in regulating and controlling the hair cycle, Distinct functional stages of dermal papilla cells (DPC) are involved in this process, thu s suggesting that the dermal papilla is a highly specialized suborgan of the pilosebaceous unit, The aim of the present study was to investi gate the functional properties of cultured DPC in various assays and t o compare their functional properties with those of dermal fibroblasts (DFB), In monolayer cell cultures DPC showed an aggregative growth pa ttern, different to that of DFB, and lower proliferation rates, as com pared to the controls, Adhesion assays performed using a (51)[Cr]label ling method showed strong adhesion of both cell populations to collage n types I and IV, fibronectin and laminin, but DPC in vitro showed sig nificantly higher adhesiveness to collagen type IV, a major component of the basement membrane of dermal papillae in Five, The capacity of D PC to reorganize extracellular matrix components, as measured by gel c ontraction with three-dimensional collagen type I lattices, proved to be significantly lower than that of DFB and, moreover, DPC lysed the c ollagen lattices completely after 48 h in culture, The funtional diffe rences between DPC and DFB were paralleled by higher surface expressio n and synthesis levels of the beta(1), alpha(1), and as chains of inte grin adhesion receptors in DPC, as detected by fluorescence-activated cell-sorter analysis and radioimmunoprecipitation. These findings prov ide evidence that DPC are a highly specialized cell population, which clearly differs from another mesenchymal cell type, DFB, After their i solation and cultivation in vitro, DPC still preserve functional prope rties related to important steps of cell-matrix interaction involved i n the hair cycle.