KERATINOCYTE CONDITIONED MEDIUM STIMULATES TYPE-IV COLLAGENASE SYNTHESIS IN CULTURED HUMAN KERATINOCYTES AND FIBROBLASTS

We have previously shown that conditioned medium from cultured human k eratinocytes stimulates proliferation of a variety of cell types invol ved in wound healing, as well as re-epithelialization of wounds in hum an skin in vitro. We now present evidence for an autocrine/paracrine c ontrol of the synthesis of type IV collagenases in human keratinocytes and fibroblasts. During wound healing, keratinocytes migrate over the wound bed, an activity coupled with lysis of basement membranes, and hence requiring the presence of collagenases. Collagenases are also ne eded for the production and remodelling of the granulation tissue. In order to study the autocrine/paracrine control of collagenase producti on in keratinocytes and fibroblasts, we stimulated these cells in cult ure with conditioned medium from cultured keratinocytes. Protease synt hesis was determined by affinity labelling with H-3-diisopropylfluorop hosphoridate (DFP) and by zymography. Keratinocyte-conditioned medium was found to increase the expression of 72 and 92 kDa type IV collagen ase in human keratinocytes, and the 72 kDa collagenase in human fibrob lasts, indicating that an autocrine/paracrine control mechanism is inv olved in collagenase production in these cell types during wound heali ng. This increased expression of collagenases could be partly responsi ble for the stimulated healing seen in wounds treated with sheets of c ultured keratinocytes.