library_construction_protocol: The mice were perfused with 4℃ PBS, and then the tissues were collected, dissected in PBS to remove excess hair and blood. Then the aorta were finely minced and transferred to 5ml digestion mix (HBSS, 2U/µl Collagenase type I (17100017, Gibco), 2U/µl Collagenase type II (LS004177, Worthington)). The digestion mix included tissue were incubated at 37℃ for 15 minutes. The cell suspension was filtered through 40μm cell strainer and then pelleted by centrifugation at 500g for 5 minutes. Next the cells were incubated in red-blood-cell lysis buffer (1ml, eBioscience, 00-4333-57) at room temperature for 1 min. Add ten times the volume of cold PBS, centrifuged and resuspended with cold PBS. At last, the cells were pelleted by centrifugation at 300g for 5 minutes and resuspended with 100 µl cold PBS. The cell suspense was loaded in 10x Chromium controller to generate GEMs, which were further processed into single cell 5ʹ gene expression libraries using Chromium Single Cell 5ʹ Library Kit (v2 Chemistry).