VEC undergo mesenchymal transition. Aortic valve sections from WT and LDLR mice fed with HFD for 6 months were stained with vimentin (A), p-Smad2 (B), α-SMA (C), isolectinB4 (D), and α-1 type I collagen (E); nuclei were stained with DAPI (blue). Red arrows indicate a subset of cells expressing high levels of these markers in LDLR mice, but not WT. (F) Valve sections from WT and LDLR mice fed with HFD for 6 months were stained with vimentin and isolectinB4. (G) Quantification of double-positive (isolectinB4+vimentin), vimentin-positive cells, and total nucleated cells by counting DAPI. (H) Real-time polymerase chain reaction for Col1α1 in human umbilical vein endothelial cells stimulated with platelet-derived TGF-β1 for 3 hours, with or without anti-TGF-β1 antibody (AF-101-NA).