Single-cell RNA-seq reveals cellular heterogeneity of mouse carotid artery under disturbed flow

Disturbed blood flow (d-flow) has been known to induce changes of the cells in the arterial wall, increasing the risk of atherosclerosis. However, the heterogeneity of the vascular cell populations under d-flow remains less understood. To generate d-flow in vivo, partial carotid artery ligation (PCL) was performed. Seven days after ligation, single-cell RNA sequencing of nine left carotid arteries (LCA) from the PCL group (10,262 cells) or control group (14,580 cells) was applied and a single-cell atlas of gene expression was constructed. The integrated analysis identified 15 distinct carotid cell clusters, including 10 d-flow-relevant subpopulations. Among endothelial cells, at least four subpopulations were identified, including Klk8(hi) ECs, Lrp1(hi) ECs, Dkk2(hi) ECs, and Cd36(hi) ECs. Analysis of GSVA and single-cell trajectories indicated that the previously undescribed Dkk2(hi) ECs subpopulation was mechanosensitive and potentially transformed from Klk8(hi) ECs under d-flow. D-flow-induced Spp1(hi) VSMCs subpopulation that appeared to be endowed with osteoblast differentiation, suggesting a role in arterial stiffness. Among the infiltrating cell subpopulations, Trem2(hi) M phi, Birc5(hi) M phi, DCs, CD4(+) T cells, CXCR6(+) T cells, NK cells, and granulocytes were identified under d-flow. Of note, the novel Birc5(hi) M phi was identified as a potential contributor to the accumulation of macrophages in atherosclerosis. Finally, Dkk2(hi) ECs, and Cd36(hi) ECs were also found in the proatherosclerotic area of the aorta where the d-flow occurs. In conclusion, we presented a comprehensive single-cell atlas of all cells in the carotid artery under d-flow, identified previously unrecognized cell subpopulations and their gene expression signatures, and suggested their specialized functions.

Automated summary

The study showed that disturbed blood flow can alter arterial wall cells, increasing the risk of atherosclerosis. Single-cell RNA sequencing revealed multiple cell subpopulations related to disturbed blood flow, including mechanosensitive endothelial cells and smooth muscle cells potentially impacting arterial stiffness.