Contraction of collagen gels by intestinal epithelial cells depends on microfilament function.

We have developed a model system to quantify the tractional forces generated by intestinal epithelial cells during organization into a confluent epithelial cell sheet. In this model system, IEC-6 cells, a rat intestinal crypt cell line, rapidly contracted collagen gels reducing the gel surface area by 97% at 24 hr. The tractional forces measured by gel contraction were directly related to the number of cells added and were inversely related to the collagen concentration of the gel. Actin microfilament function was required for gel contraction, but microtubular function was not. Fetal bovine serum and protein synthesis were required for maximal gel contraction. IEC-6 (5 x 10(5)) cells per gel and fibroblasts (5 x 10(4)) cells added to collagen gels resulted in contraction of the gels by 50% at 24 hr. Therefore, intestinal epithelial cells and fibroblasts generate tractional forces of similar strength capable of organizing the surrounding extracellular matrix, which should be considered in models of intestinal morphogenesis and repair.