Fibroblast contraction of a collagen-GAG matrix

Contractile cells, found in wounded or diseased tissues, are associated wit h the formation of scar tissue. The complexity of contraction in vivo has l ed to the development of models of contraction by cells in vitro. In this w ork, a device was developed which quantitatively measured the contractile f orce developed by fibroblasts seeded into a collagen-glycosaminoglycan poro us matrix in vitro. This device differed from most of those previously desc ribed in that it directly transferred cellular contractile force to the for ce transducer (a cantilever beam) and that it used a porous matrix rather t han a collagen gel. The data for the increase in contractile force with tim e were fit to a mathematical equation using two fitting parameters. Data we re then compared using the fitting parameters and the cell density. A study of the effect of cell density on the contractile force resulted in a linea rly proportional relationship. Subsequent normalization of force by cell de nsity or number resulted in a value of contractile force per cell, I nN, th at was independent of cell density. The time for the contractile force to d evelop was also independent of cell density. These results suggest that, in this system, cells develop contractile force individually, irrespective of the force generated by surrounding cells. (C) 2001 Elsevier Science Ltd. A ll rights reserved.