[Mechanical behavior of fibroblasts included in collagen lattices]

Striae distensae are characterized by linear, smooth bands of atrophic-appearing skin. Excessive steroid activity, genetic and mechanical factors and inherited defects of connective tissues are the most frequent causes of this disease. Fibroblasts derived from women presenting striae distensae lesions were included into collagen gels to study their mechanical behavior: capacity to contract free-floating lattices and to produce isometric force in tense lattices. To measure the retracted lattice diameter, the culture dishes were placed on a transparent metric scale. An isometric force system was used to study quantitatively the forces developed during lattice contraction. alpha 2 beta 1 integrins expression (transmembrane receptors) was evaluated by flux cytometry. Striae distensae fibroblasts contract collagen gels slower than normal human fibroblasts but the final contraction is similar. They produce a greater isometric force which is associated with enhanced alpha 2 beta 1 integrins expression. By their mechanical properties, striae distensae fibroblasts appear as a different population from normal fibroblasts.