Growth characteristics of skin fibroblasts and 3T3 cells entrapped by polymerizing fibrin.

Skin fibroblasts as well as 3T3 cells were cultured after entrapping freshly prepared cells in medium containing polymerizing fibrin. In contrast to cells grown on plastic substratum, fibrin-clot-cultured cells became highly elongated forming strands of cells. The strands interconnected by lateral cellular protrusions so that horizontal networks of cells were present throughout the clots. Cell growth as well as stretching were dependent upon the concentrations of fibrin. Highest growth rates were obtained with low fibrin concentrations (0.3 mg fibrinogen per ml). As shown by deprivation experiments nutritional limitations appear to be responsible for differences in growth rates observed in fibrin clots of higher density. In this system the fibrin meshwork serves as substratum for adhesion, elongation and multiplication of fibroblasts. The method makes it possible to study single cells in culture and the effects of persistent microenvironmental influences.