von Willebrand factor (VWF) mediates primary hemostasis and
thrombosis in response to hydrodynamic forces. We previously showed that high shear promoted self-association of VWF into hyperadhesive strands, which can be attenuated by
high-density lipoprotein (HDL) and
apolipoprotein A-I. In this study, we show that
low-density lipoprotein (
LDL) binds VWF under shear and enhances self-association. Vortexing VWF in tubes resulted in its loss from the
solution and deposition onto tube surfaces, which was prevented by HDL. At a stabilizing HDL concentration of 1.2 mg/mL, increasing concentrations of
LDL progressively increased VWF loss, the effect correlating with the
LDL-to-HDL ratio and not the absolute concentration of the
lipoproteins. Similarly, HDL diminished deposition of VWF in a post-in-channel
microfluidic device, whereas
LDL increased both the rate and extent of strand deposition, with both purified VWF and plasma. Hypercholesterolemic human plasma also displayed accelerated VWF accumulation in the
microfluidic device. The initial rate of accumulation correlated linearly with the
LDL-to-HDL ratio. In Adamts13-/- and Adamts13-/-LDLR-/- mice, high
LDL levels enhanced VWF and platelet adhesion to the myocardial microvasculature, reducing cardiac perfusion, impairing systolic function, and producing early signs of
cardiomyopathy. In wild-type mice, high plasma
LDL concentrations also increased the size and persistence of VWF-platelet thrombi in
ionophore-treated mesenteric microvessels, exceeding the accumulation seen in similarly treated ADAMTS13-deficient mice that did not receive
LDL infusion. We propose that targeting the interaction of VWF with itself and with
LDL may improve the course of
thrombotic microangiopathies,
atherosclerosis, and other disorders with defective microvascular circulation.