LDL enhances microvascular thrombosis induced by calcium ionophore in WT C57BL/6 mice. WT mice (aged 3-4 weeks) were injected with platelets that were isolated from WT donors and fluorescently labeled with calcein AM ex vivo. Their mesenteric vessels were exposed and topically treated with calcium ionophore to induce VWF secretion. The dynamics of platelet VWF thrombus formation and resolution in mesenteric vessels were monitored and quantified. For the LDL-pretreated group, mice received 100 mg/kg of purified human LDL through tail-vein injection 10 minutes before calcium ionophore treatment. (A) Sequential images taken at the indicated times after the application of calcium ionophore. Images taken at similar times from the control and LDL-pretreated WT mice are aligned. Original magnification ×200. (B) Mean fluorescence intensity (MFI) of platelet thrombi was quantified for each frame of the recorded video and plotted against time. (C) Platelet thrombi >30 μm in diameter were quantified. (D) Time to thrombus resolution was quantified. Upon calcium ionophore stimulation, platelets immediately began to accumulate on the vessel wall. Adhesion was monitored, and the time required for the fluorescence value to return to baseline was measured. LDL treatment significantly prolonged the time required for platelet adhesion to return to baseline. The data were analyzed using Student t test; the P values are indicated.