Paracrine effects of cultured MSCs. The secretion of a broad range of bioactive molecules is now believed to be the main mechanism by which MSCs achieve their therapeutic effect and it can be divided into six main categories: (1) immunomodulation; (2) antiapoptosis; (3) angiogenesis; (4) support of the growth and differentiation of local stem and progenitor cells; (5) antiscarring; and (6) chemoattraction. bFGF = basic fibroblast growth factor; CCL = CC chemokine ligand; CXCL = chemokine (C-X-C motif) ligand; ECM = extracellular matrix; GM-CSF = granulocyte–macrophage colony-stimulating factor; HGF = hepatocyte growth factor; iDC = invasive ductal carcinoma; IGF-1 = insulin growth factor-1; LIF = leukaemia-inhibitory factor; M-CSF = macrophage colony-stimulating factor; mDC = macrophage-derived chemokine; NK = natural killer; PGE2 = prostaglandin E2; SCF = stem cell factor; SDF-1 = stromal cell-derived factor 1; TGF-β = transforming growth factor-β; VEGF = vascular endothelial growth factor. Note. From “Mechanisms involved in the therapeutic properties of mesenchymal stem cells” by da Silva Meirelles, et al., 2009. Cytokine Growth Factor Reviews, 20, p. 419–427. Copyright 2009, Elsevier Ltd. Reprinted with permission.