Fibroblast-like cells from tendons differ from skin fibroblasts in their ability to form three-dimensional structures in vitro.

Tendon samples cultured in vitro produced cells (TC) with fibroblast-like morphology and confluence occurred within 5 weeks. Histological staining demonstrated proteoglycan and collagen secretion by TC. Immunohistochemical staining revealed type I collagen but no type III. Assay of total collagen demonstrated a rapid increase in synthesis with time in culture. Cultures allowed to become 'superconfluent' spontaneously formed three-dimensional structures after about 4 weeks, which became macroscopic, tendon-like structures (TLS). Cells within TLS seemed under cell-generated tension. Haematoxylin and eosin staining of sections of tendon, of TLS and of TC cultures demonstrated similarities in morphology. These studies were performed using human and rabbit cells and findings were similar for the two species, but with some differences in cell metabolism. Skin fibroblasts were also cultured as a comparison.