Cluster 1 represents a distinct population of cells expressing genes involved in inflammation (Ifi27l2a) [67], hyperlipidemia (Gata4) [68], VSMC phenotypic modulation (Meox1) [69], calcification and bone formation (Htra4, Meox1) [70,71] (Figure 5a,b and Supplementary Figure S4b ). Here, HTRA4 is linked to hyperlipidemia.