Reversible and irreversible differentiation of cardiac fibroblasts.
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ABSTRACT: AIMS: Differentiation of cardiac fibroblasts (Fbs) into myofibroblasts (MyoFbs) is responsible for connective tissue build-up in myocardial remodelling. We examined MyoFb differentiation and reversibility. METHODS AND RESULTS: Adult rat cardiac Fbs were cultured on a plastic substratum providing mechanical stress, with conditions to obtain different levels of Fb differentiation. Fb spontaneously differentiated to proliferating MyoFb (p-MyoFb) with stress fibre formation decorated with alpha-smooth muscle actin (?-SMA). Transforming growth factor-?1 (TGF-?1) promoted differentiation into ?-SMA-positive MyoFb showing near the absence of proliferation, i.e. non-p-MyoFb. SD-208, a TGF-?-receptor-I (TGF-?-RI) kinase blocker, inhibited p-MyoFb differentiation as shown by stress fibre absence, low ?-SMA expression, and high proliferation levels. Fb seeded in collagen matrices induced no contraction, whereas p-MyoFb and non-p-MyoFb induced 2.5- and four-fold contraction. Fb produced little collagen but high levels of interleukin-10. Non-p-MyoFb had high collagen production and high monocyte chemoattractant protein-1 and tissue inhibitor of metalloproteinases-1 levels. Transcriptome analysis indicated differential activation of gene networks related to differentiation of MyoFb (e.g. paxilin and PAK) and reduced proliferation of non-p-MyoFb (e.g. cyclins and cell cycle regulation). Dedifferentiation of p-MyoFb with stress fibre de-polymerization, but not of non-p-MyoFb, was induced by SD-208 despite maintained stress. Stress fibre de-polymerization could also be induced by mechanical strain release in p-MyoFb and non-p-MyoFb (2-day cultures in unrestrained 3-D collagen matrices). Only p-MyoFb showed true dedifferentiation after long-term 3-D cultures. CONCLUSIONS: Fb, p-MyoFb, and non-p-MyoFb have a distinct gene expression, ultrastructural, and functional profile. Both reduction in mechanical strain and TGF-?-RI kinase inhibition can reverse p-MyoFb differentiation but not non-p-MyoFb.
SUBMITTER: Driesen RB
PROVIDER: S-EPMC3928002 | biostudies-literature | 2014 Mar
REPOSITORIES: biostudies-literature
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