Vascular Smooth Muscle Cells (SMCs) exhibit a significant degree of phenotypic plasticity in atherosclerotic lesions. Previously, this phenotypic plasticity, and specifically the re-differentiation of SMCs into macrophages, has been modeled in vitro using cholesterol treatment. We performed a meta-analysis of five different murine SMC lineage tracing single-cell RNA sequencing (scRNA-seq) experiments performed by four different research groups; we identified 24 different cell types and find considerable differences in the proportion of recovered normal ‘contractile’ SMCs and SMC-derived macrophages between experiments. In addition, we performed bulk RNA-seq on cultured murine SMCs with and without cholesterol treatment for 0, 24, or 48 hours. We find that cholesterol treatment regulates transcripts associated with the induction of the unfolded protein response, reduction of cholesterol biosynthesis, and reduction in cell proliferation. Additionally, chromatin immunoprecipitation followed by high-throughput sequencing for H3K27ac performed on in vitro SMCs treated and untreated for 0, 24, or 48 hours reveals that AP-1 and ATF4 binding motifs are found more frequently at cholesterol treatment specific H3K27ac chromatin sites. Finally, we compared transcriptomic data between in vivo vascular cell types identified in our meta-analysis and in vitro SMCs. We additionally included scRNA-seq data and microarray data collected for in vitro SMCs and bulk RNA-seq data collected for M1, M2, and oxLDL treated macrophages. We find that compared to the phenotypic plasticity observed in vivo, cholesterol exhibits modest effects on the transcriptomes of in vitro SMCs and does not reproduce the changes observed in vivo, while in vitro macrophages, especially oxLDL treated macrophages, more closely approximate their in vivo counterparts. We conclude that differences between SMC lineage-tracing scRNA-seq experiments obscures the degree to which SMC-derived macrophages are present in murine atherosclerotic plaques, that cholesterol has modest effects on in vitro SMC transcriptomes, and that the effects of cholesterol do not reproduce the phenotypic plasticity observed in vivo.