(A) HA-VSMCs treated with ox-LDLs, co-cultured HA-VSMCs (bottom chamber) with ox-LDL-treated THP-1 cells (upper chamber), co-cultured HA-VSMCs (bottom chamber) with CXCL12 siRNA transfected THP-1 cells and treated with ox-LDL (upper chamber), and co-cultured HA-VSMCs (bottom chamber) with CXCL12 siRNA transfected THP-1 cells and treated with ox-LDL and CXCL12 (upper chamber), were seeded into Transwell plates and incubated for the indicated times. The upper chamber was then removed, and cell proliferation was detected with the MTT assay. (B) Cells were treated as in (A); after 48 h, the upper chamber was removed, and the HA-VSMCs were fixed and stained with Oil Red O. The respective images are shown (×200). (C) Cells were treated as in (A); after 48 h, the upper chamber was removed, the culture medium in the bottom chamber was collected, and CXCL12 was detected by ELISA. (D) Cells were treated as in (A); after 48 h, the upper chamber was removed, the HA-VSMCs were collected and lysed with lysis buffer, and Western blotting was performed. ***, P<0.001, HA-VSMCs+THP-1-NC siRNA+ox-LDL vs. HA-VSMCs+THP-1-CXCL12 siRNA+ox-LDL, HA-VSMCs+THP-1-CXCL12 siRNA+ox-LDL vs. HA-VSMCs+THP-1-CXCL12 siRNA+ox-LDL+CXCL12. 1, HA-VSMCs were treated with ox-LDL. 2, THP-1 cells were transfected with NC siRNA, treated with ox-LDLs, and co-cultured with HA-VSMCs. 3, THP-1 cells were transfected with CXCL12 siRNA, treated with ox-LDLs, and co-cultured with HA-VSMCs. 4, THP-1 cells were transfected with CXCL12 siRNA; next, CXCL12 and ox-LDLs were added to the cells, which were then co-cultured with HA-VSMCs.