Abstract
Myofibroblasts and transforming growth factor-β1 (TGF-β1) are key elements of cardiac tissue fibrosis development. The aim of this study was to determine whether the ability of TGF-β1 to affect the contractile activity of cardiac fibroblasts depends on their differentiation into myofibroblasts.
Cardiac fibroblasts (from male adult Wistar rats) from passage two were cultured to confluency and incubated on a hydrated collagen gel with and without TGF-β1 (0, 20, 40, 100, 200, 400 or 600 pmol/L) for one, two and three days in a Dulbecco's Modified Eagle's Medium without foetal bovine serum.
TGF-β1 dose-dependently increased the contraction of collagen gel mediated by cardiac fibroblasts, reaching a maximal effect at 100 pmol/L TGF-β1. TGF-β 1 also stimulated 3H-thymidine incorporation and total protein content in cardiac fibroblasts in the collagen gel lattice . TGF-β 1 dose-dependently induced an increase in αsmooth muscle actin, a marker of myofibroblasts. The TGF-β1-induced reduction of area of the collagen gel was negatively correlated to the TGF- R β 1-evoked appearance of α-smooth muscle actin in the collagen gel matrix.
Our data demonstrate that TGF-β1 increased the contractile activity of adult rat cardiac fibroblasts and their ability to differentiate into myofibroblasts. Because contractile activity was correlated with differentiation, the influence of TGF-β1 on cardiac fibroblast-induced collagen gel contraction might depend on the promotion of myofibroblast differentiation.
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