Fibrin clot retractile activity of mouse fibroblasts during growth and aging.

This study aimed at evaluating by a quantitative assay the fibrin clot retractile activity (FCR) of C3H embryo fibroblasts during their growth and aging in culture. Cell from primary and subsequent subcultures were tested at defined times from seeding, in a specially devised micromethod. Results indicate that cell-induced FCR has a kinetic similar to platelet-induced FCR; it depends on the number of cells and time of incubation in the system. It is absent or low in cells harvested from primary culture, then increases and remains high in the following doublings decreasing sharply at the end of the replicative life span in culture.