INTRODUCTION: Monocytes comprise heterogeneous cell populations. However, beyond traditionally considered as precursors of tissue macrophages, heterogeneity and detailed effects of monocytes in acute aortic dissection (AAD) are largely unknown. OBJECTIVES: To investigate the role of brain soluble acid protein 1 positive (BASP1 METHODS: Monocyte/macrophage heterogeneity in both human peripheral blood and aortic tissues were assayed by scRNA-seq. Monocyte trafficking and lineage tracing were detected by immunofluorescence and using BASP1-CreER/Lyz2-DreER-tdT reporter mice with AAD. The effects and underlying mechanism were investigated by laser speckle image, ultrasound imaging, Co-IP, ChIP-sequencing. Conditional knockout of BASP1 on monocyte and BASP1 siRNA were used to observe BASP1 RESULTS: "PIP2-SP1-ACTN1/VAV3" and "ITGB1-Rac1-GSN" signalling mediated BASP1 CONCLUSION: Interpretation BASP1