Abstract Th0055: Smooth Muscle Embryonic Origin Drives Differential Response to Injury in Atherosclerosis

Atherosclerosis is the hallmark of multiple vascular diseases including peripheral arterial disease, carotid artery disease, as well as others, and contributes to significant disease burden. Vascular smooth muscle cells (SMCs) throughout the arterial tree arise from different embryonic origins, with each major arterial region representing a unique developmental lineage. Our goal was to investigate if SMCs from different regions (ie different embryonic origins) of the arterial tree exhibited unique gene expression profiles in atherosclerotic versus wildtype mice. Genetic ApoE-/- mice were fed a Western diet for at least 6 weeks and then their vascular tree was dissected and divided into aortic arch and carotid, coronary artery, thoracic aorta, and abdominal aorta to represent neural crest, proepicardium, somites (paraxial mesoderm), and splanchnic mesoderm origins, respectively. Similar dissection and isolation was performed for wildtype C57BL6 controls on a regular diet. Single cell RNA-sequencing was performed on the various vascular regions from ApoE-/- and wildtype mice. Differential gene expression analysis was performed to identify the top six most upregulated genes in SMCs from wildtype and ApoE-/- vasculature from the different anatomic regions. For each sample, the six genes identified were expressed by the majority (>50%) of the SMCs in each sample. We performed gene ontology analysis for upregulated genes in ApoE-/- and wildtype SMCs for all of the different vascular regions and found that neural crest-derived SMC from the aortic arch and carotid artery of ApoE-/- mice displayed significant upregulation in fatty acid and lipid metabolic pathways compared to muscle contraction pathways in wildtype mice. The top most upregulated genes in ApoE-/- neural crest-derived SMCs were Pdk4, Fabp3, Abra, Xirp1, Ccn1, and Hbb-bs . There were similar unique differential gene profiles in SMCs representative of the other embryonic origins which differed in wildtype versus ApoE-/- mice. Our results identify that embryonic origin drives unique SMC gene signatures in the setting of atherosclerosis, which likely underlies the altered smooth muscle phenotype observed in this disease. As such, our findings identify important genetic SMC-specific targets in the development and perhaps treatment of atherosclerosis.