Fig. 1.

Activated fibroblasts are key players in the fibrotic process and extracellular matrix (ECM) production. Fibroblasts involved in fibrosis can be derived from vascular smooth muscle cells, pericytes, fibrocytes, endo- and epithelial cells or resident fibroblasts. Depending on their origin, these cells undergo proliferation, differentiation and endothelial/epithelial-to-mesenchymal transition (EndoMT/EMT) and the emerging myofibroblasts/activated fibroblasts excessively synthesize and secrete ECM proteins that contribute to fibrosis