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Keywords:

Actins, Animals, Blotting, Western, Cell Differentiation, Cells, Cultured, Collagen, DNA, Fibroblasts, Gels, Male, Myocardial Contraction, Myocardium, Rats, Rats, Wistar, Thymidine, Transforming Growth Factor beta, Transforming Growth Factor beta1, Science & Technology, Life Sciences & Biomedicine, Pharmacology & Pharmacy, cardiac fibroblasts, collagen, gel contraction, myofibroblasts, transforming growth factor beta(1), SMOOTH-MUSCLE ACTIN, ANGIOTENSIN-II, FACTOR-BETA, GROWTH-FACTOR-BETA-1 PROMOTES, MATRIX CONTRACTION, IN-VITRO, EXPRESSION, CELLS, INDUCTION, QUIESCENT, 1115 Pharmacology and Pharmaceutical Sciences, 3214 Pharmacology and pharmaceutical sciences

Abstract:

Myofibroblasts and transforming growth factor-beta 1 (TGF-beta 1) are key elements of cardiac tissue fibrosis development. The aim of this study was to determine whether the ability of TGF-beta 1 to affect the contractile activity of cardiac fibroblasts depends on their differentiation into myofibroblasts. Cardiac fibroblasts (from male adult Wistar rats) from passage 2 were therefore cultured to confluency and incubated on a hydrated collagen gel, both with and without TGF-beta 1 (0, 20, 40, 100, 200, 400 or 600 pmol/l), for 1, 2 and 3 days in a Dulbecco's Modified Eagle's Medium (DMEM) without fetal bovine serum (FBS). Growing cultures of cardiac fibroblasts were obtained by incubating second-passage fibroblasts in DMEM with 10% FBS with or without TGF-beta 1 (0 to 600 pmol/l) for 6 days. These fibroblasts were then further incubated on the collagen gel for 1, 2 and 3 days in DMEM without FBS. TGF-beta 1 dose-dependently increased the contraction of collagen gel mediated by cardiac fibroblasts, either added directly to the gel or after growing of the cardiac fibroblasts in the presence of TGF-beta 1 for 6 days, reaching a maximal effect at 100 pmol/l TGF-beta 1. In both culturing conditions, TGF-beta 1 also stimulated the [3H]-thymidine incorporation and the total protein content in the cardiac fibroblasts in the collagen gel lattice. TGF-beta 1 dose-dependently induced an increase in alpha-smooth muscle actin, a marker of myofibroblasts, in both culturing conditions. The TGF-beta 1-induced reduction of area of the collagen gel was negatively correlated to the TGF-beta 1-evoked appearance of alpha-smooth muscle actin in the collagen gel matrix. TGF-beta 1 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-beta 1 on cardiac fibroblast-induced collagen gel contraction may depend on the promotion of myofibroblast differentiation.