Reversible and irreversible differentiation of cardiac fibroblasts

• Published in: Cardiovascular research 2014-03, Vol.101 (3), p.411
• Main Authors: Driesen, Ronald B, Nagaraju, Chandan K, Abi-Char, Joëlle, Coenen, Tamara, Lijnen, Paul J, Fagard, Robert H, Sipido, Karin R, Petrov, Victor V
• Format: Article
• Language: English
• Subjects: Animals; Cell Differentiation - drug effects; Cell Differentiation - radiation effects; Cells, Cultured; Collagen - metabolism; Gene Expression - drug effects; Male; Myofibroblasts - cytology; Myofibroblasts - metabolism; Pteridines - pharmacology; Rats; Rats, Wistar; Receptors, Transforming Growth Factor beta - metabolism; Stress, Physiological; Transforming Growth Factor beta1 - metabolism
• ISSN: 1755-3245
• DOI: 10.1093/cvr/cvt338

Differentiation of cardiac fibroblasts (Fbs) into myofibroblasts (MyoFbs) is responsible for connective tissue build-up in myocardial remodelling. We examined MyoFb differentiation and reversibility. 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 (α-SMA). Transforming growth factor-β1 (TGF-β1) promoted differentiation into α-SMA-positive MyoFb showing near the absence of proliferation, i.e. non-p-MyoFb. SD-208, a TGF-β-receptor-I (TGF-β-RI) kinase blocker, inhibited p-MyoFb differentiation as shown by stress fibre absence, low α-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. Fb, p-MyoFb, and non-p-MyoFb have a distinct gene expression, ultrastructural, and functional profile. Both reduction in mechanical strain and TGF-β-RI kinase inhibition can reverse p-MyoFb differentiation but not non-p-MyoFb.