Conditioned medium from M1-FCs stimulates HAECs to undergo EndMT in vitro. HAECs were treated with conditioned medium from different phenotypic macrophages: conditioned medium from (A) M1, (B) M2a and (C) M2c macrophages and (D) M1, (E) M2a and (F) M2c-derived FCs at 1:1 ratio with EBM-2 for 6 days. HAECs treated with conditioned medium from M1-FCs lost the typical cobblestone-like morphology and gained a spindle-like appearance. (G) Western blot analysis of endothelial and mesenchymal cell surface markers demonstrated that HAECs incubated with conditioned medium from M1-FCs underwent EndMT. M1-FCs, M1 macrophage-derived foam cells; Con, control; Mφ, macrophage; FC, foam cell; VE-cadherin, vascular endothelial cadherin; α-SMA, α-smooth muscle actin; FSP-1, fibroblast-specific protein-1; EndMT, endothelial mesenchymal transition.