An In Vitro Study of Human Fibroblast Contractility and the Differential Effect of TGF-beta1 and TGF-beta3 on Fibroblast Contraction and Collagen Synthesis

Skin, tendons, and other tissues can heal, but with formation of scar tissue, characterized by altered biochemical composition, distorted tissue architecture, and decreased mechanical properties compared to the normal tissues. Excessive cellular contraction in wounds can lead to formation of scar tissue, whereas insufficient cellular contraction may impede wound closure. In addition, although both TGF-b1 and TGF-b3 have been found to increase cellular contraction, only TGF-b3 has been shown to reduce formation of scar tissue in rat skin wounds. Therefore, the overall objective of this project is to reduce the formation of scar tissue by regulating cellular contraction. As part of this objective, this thesis project studies human fibroblast contractility and the differential effect of TGF-b1 and TGF-b3 on human fibroblast contraction and collagen synthesis using in vitro models. Either human skin or tendon fibroblasts were used in this project, depending on the nature of the specific study.Human tendon fibroblasts were found to contract in vitro and the degree of contraction was dependent on serum concentration. Further, a multi-station culture force monitor (CFM) system was developed to characterize cellular contraction. Using this system, human tendon fibroblasts were found to have a significantly lower maximum contraction force and a markedly different contraction pattern than human skin fibroblasts, illustrating the ability of this system to differentiate between cells from different tissues. In addition, the effect of TGF-b1 and TGF-b3 on cellular contraction and collagen synthesis of human skin fibroblasts was studied using the CFM system. Both TGF-b1 and TGF-b3 were found to increase human fibroblast contraction and collagen synthesis, but TGF-b3 increased cellular contraction and collagen synthesis to a lesser extent than TGF-b1. As there is great interest in improving the quality of healing tissue, these studies provide a foundation to further study the cellular and molecular mechanisms of tissue wound healing. In addition, these findings suggest that TGF-b3 instead of TGF-b1 may be applied to regulate tendon fibroblast contraction, which may reduce formation of scar tissue in healing tendons. Future studies will continue to elucidate the relationship between cellular contraction and collagen synthesis.