Collagen synthesis in scleroderma: selection of fibroblast populations during subcultures

In progressive systemic scleroderma, excessive deposition of collagen leads to fibrosis of several tissues including the skin. It has been found that different populations of fibroblasts are present in scleroderma skin; these can be obtained by establishing cell cultures from different layers of the involved skin. Excessive overproduction of collagen was noted in primary cultures of cells obtained from deeper layers of the skin of patients in an early stage of the disease, whereas control fibroblasts did not manifest significant variations dependent on the layers of skin used to initiate the cultures. The synthesis of type-I and -III collagen was found to be altered concomitantly. The production of collagen and collagenous proteins was then followed during subcultivations of overproducing fibroblasts. In many cell strains, increased synthesis of collagen and/or non-collagenous proteins had already been lost after the first subcultivation, whereas overproduction was stable in others. However, after five passages, most of the cultures showed normal collagen synthesis, which probably indicates a loss of phenotype due to successive subcultures or overgrowth by another population of fibroblasts.