Stress-dependent effects of platelet-derived growth factor-BB on fibroblast migration and traction differ in collagen and fibrin

We used our novel assays of cell behavior in tissue equivalents to study the dose-response effects of PDGF-BB on RDF migration and traction in mechanically stressed and stress-free type I collagen and fibrin gels. PDGF-BB increased fibroblast migration significantly in all assays, but the effects on traction depended on the presence of stress and the nature of the ECM. PDGF-BB decreased fibroblast traction in stressed collagen gels, but increased traction in stress-free gels. No statistical conclusion could be inferred for stressed fibrin gels, and increasing PDGF-BB decreased traction in stress-free fibrin gels. These results demonstrate the complex response of fibroblasts to environmental cues, and point to opportunities to orchestrate cell behavior to affect the outcome of wound healing.