Cellular and enzymatic features of thrombi in humans are vascular bed dependent

Mechanisms behind vascular remodeling following thrombosis are unclear. Although acute arterial thrombosis in the cerebrovascular circulation has devastating consequences and requires immediate attention, the management of venous thromboembolism (VTE) varies significantly. Our goal was to determine the molecular signatures and cellular content of thrombus extracted using a catheter to gain insight into vascular remodeling. Twenty-five patients underwent catheter-directed thrombectomy (CDT); 13 for cerebrovascular accident (CVA), 8 for pulmonary embolism, and 4 for deep vein thrombosis. Protein and RNA were extracted from thrombi to enable immunoblotting, RNA sequencing, and quantification of gene expression. The time from symptom onset to thrombus extraction was 7.7 ± 1.9 hours for CVA and 109 ± 55 hours for VTE. Protein concentration, white blood cell content (monocytes), and red blood cell content were greater in venous thrombus than in arterial thrombus, whereas the platelet content was similar. Both venous and arterial thrombi contained several zinc endopeptidases belonging to the matrix metalloproteinase (MMP) family. MMP9 activity in venous thrombus was greater than arterial thrombus (61 ± 9 ng/mL per μg protein vs 25 ± 6 ng/mL per μg protein; <i>P</i> = .005). Arterial and venous thrombi displayed surprisingly different phenotypes, with biologically active enzymes promoting blood vessel remodeling and enzymatic activity proportional to thrombus age extracted from the veins. These mechanistic data may support the role of early CDT in venous circulation to avoid irreversible vascular remodeling.