Establishment of Atherosclerosis Mouse Models

A total of 50 male ApoE knockout (ApoE^–/–) mice (aged 8 weeks, weighing 20 ± 2 g, C57BL/6 background) were purchased from the Experimental Animal Center of Peking University. Ten ApoE^–/– mice were fed with normal diet to serve as the control, while the remaining 40 ApoE^–/– mice were fed with high-fat and high-cholesterol atherogenic foods (containing 20.0% fat, 19.5% casein, and 0.5% cholesterol) serving as the high-fat diet (HFD) group. The HFD mice were then treated with short hairpin RNA-negative control (sh-NC) vector, sh-SDC2, agomir NC, and miR-9 agomir. The miR-9 agomir or agomir NC was dissolved in 0.2 mL normal saline and injected into the mice at a dose of 80 mg/kg/d via the tail vein once a day for ten consecutive days (Yu et al., 2020). Lentivirus carrying oe-SDC2 or sh-SDC2 was then injected into the mice at a dose of 1 × 10⁷ PFU/mouse via the tail vein, once every 2 days. The survival rate of atherosclerosis mouse models was calculated to be 85% (34/40). After feeding for 8 weeks, all mice were euthanized. Fresh whole blood samples were extracted before euthanasia and the mice were deprived of food but not water for 24 h before euthanasia. Finally, eight mice from each group were randomly selected for subsequent experimentation.