Mechanical strain increases type I collagen expression in pulmonary fibroblasts in vitro

Tissue remodeling is an adaptive response to mechanical tension in the lung. However, the role of pulmonary fibroblasts in this response has not been well characterized. This study investigates the influence of extracellular matrix on the response of fibroblasts to mechanical strain. Cells were cultured on flexible-bottom surfaces coated with fibronectin, laminin, or elastin and exposed to strain. Under these conditions, fibroblasts align perpendicular to the force vector. This stimulus results in an increase in alpha(1)(I) procollagen mRNA in cells cultured on laminin or elastin but not fibronectin. Increased alpha(1)(I) procollagen mRNA was detected 6 h after exposure to strain and reached control levels by 72 h. [(3)H]proline incorporation into newly synthesized procollagen reflects changes in mRNA levels. Strained fibroblasts cultured on laminin or elastin incorporated 190 and 114%, respectively, more [(3)H]proline into procollagen than did unstrained cells. No difference was detected in strained fibroblasts cultured on fibronectin. These results suggest that fibroblasts respond to mechanical strain in vitro, and this response is signaled by cell-extracellular matrix interactions.