RESUMO
Fibrin and hyaluronic acid are important components of the provisional wound matrix. Through interactions with fibroblasts, they provide biophysical cues that regulate the viscoelastic properties of the extracellular matrix. To understand the roles of fibrin and hyaluronic acid in a collagenous environment, we used fibroblast populated collagen lattices (collagen, collagen-fibrin, and collagen-hyaluronic acid). Compared with collagen and collagen-hyaluronic acid cultures, collagen-fibrin cultures showed less contraction, which is correlated with increased elastic (G') and complex (|G*|) moduli, and reduced proportions of dendritic fibroblasts, despite increased αv integrin expression. Stiffness decreased during culture in collagen-fibrin environment, meanwhile phase shift (δ) values increased, clearly associated with the rise in fibrinolytic and gelatinolytic activities. These processes changed the viscoelastic properties of the system toward G' and |G*| values observed on day 5 in collagen cultures. Although less collagen turnover was observed in collagen-fibrin cultures than in collagen and collagen-hyaluronic acid cultures, collagen neosynthesis was apparently insufficient to contribute to the overall viscoelastic properties of the system. Collagen-hyaluronic acid cultures showed very limited changes during time. Firstly, they exhibited the highest δ values, suggesting an increase in the viscous behavior due to the hygroscopic properties of hyaluronic acid. These results showed that fibrin and hyaluronic acid not only affect differently the viscoelastic properties of the culture, they can tune fibroblastic activity by regulating cell attachment and extracellular matrix remodeling.