Enhanced proliferation and collagen synthesis of human dermal fibroblasts in chronically photodamaged skin.

Cutaneous aging can be divided into intrinsic aging and photoaging. We investigated the influence of aging and photoaging on the proliferation and collagen synthesis of human dermal fibroblasts cultured 3-dimensionally in a collagen gel. We examined 11 human dermal fibroblast cell lines cultured from 3 newborn skins (1 day old), and both exposed and unexposed skin from 4 elderly volunteers (60, 60, 73, 76 years old), respectively. Newborn fibroblasts actively proliferated within the attached collagen gels compared with the elderly cell lines. Within the attached collagen gels in the presence of 10% fetal calf serum (FCS), the fibroblasts from exposed skin proliferated rapidly compared with fibroblasts from unexposed skin from the same individuals. In collagen gel and monolayer cultures with 1% FCS, the percentage of collagen synthesized by photoaged and aged fibroblasts decreased significantly compared with that by newborn fibroblasts. When the fibroblasts were cultured three dimensionally in attached collagen gels in the presence of 1% FCS, the relative levels of collagen synthesis by cultured fibroblasts from photoaged skin were increased significantly compared with those of aged skin fibroblasts from the same individuals. These results suggest that fibroblasts of exposed skin may be more active than those of unexposed skin and that the three-dimensional culture of fibroblast can be used as a model to investigate the influence of aging and photoaging on cell functions.