Heterogeneous synthetic phenotype of cloned scleroderma fibroblasts may be due to aberrant regulation in the synthesis of connective tissues.

Clones of dermal fibroblasts from the skin of 4 normal subjects and 5 patients with progressive systemic sclerosis (PSS; scleroderma) were established, and their synthetic and proliferative characteristics were compared. A limiting-dilution assay was used to determine frequencies of cloning in the microcultures of dermal fibroblasts plated. The clones derived from single cells were expanded in vitro and examined (in passages C-H) for growth and synthesis of glycosaminoglycan (GAG) and collagenase-sensitive protein (CSP). The clonogenicity of PSS fibroblasts was not significantly different from that of normal fibroblasts. Normal fibroblast clones were characterized by low levels of GAG and CSP synthesis, and there was a correlation between the GAG and CSP phenotypes. In contrast, clones of PSS fibroblasts were often, but not always, high producers of GAG and CSP, but there was no correlation between the levels of GAG and CSP synthesis. It appears that scleroderma skin is composed of fibroblast clones that are unable to regulate the synthesis of connective tissue components and often synthesize large amounts of connective tissue macromolecules.