heparitin-sulfate and ferric-chloride

Heparanase is an endo-glucuronidase that specifically cleaves heparan sulfate (HS) and heparin polysaccharides. The enzyme is expressed at low levels in normal tissues, but is often upregulated under pathological conditions such as cancer and inflammation. Normal human platelets express exceptionally high levels of heparanase, but the functional consequences of this feature remain unknown. We investigated functional roles of heparanase by comparing the properties of platelets expressing high (Hpa-tg) or low (Ctr) levels of heparanase. Upon activation, Hpa-tg platelets exhibited a much stronger adhesion activity as compared to Ctr platelets, likely contributing to a higher thrombotic activity in a carotid thrombosis model. Furthermore, we found concomitant upregulated expression of both heparanase and CD62P (P-selectin) upon activation of mouse and human platelets. As platelets play important roles in tumor metastasis, these findings indicate contribution of the platelet heparanase to hyper-thrombotic conditions often seen in patients with metastatic cancer.

Topics: Animals; Blood Platelets; Carotid Arteries; Cell Separation; Chlorides; Crosses, Genetic; Erythrocytes; Female; Ferric Compounds; Flow Cytometry; Gene Expression Regulation; Glucuronidase; Glycosaminoglycans; Heparitin Sulfate; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; P-Selectin; Platelet Activation; Platelet Adhesiveness; Selenoprotein P; Thrombosis; Up-Regulation

Evaluating anticoagulants in animal thrombosis models is a standard component of preclinical drug testing. Mice are frequently used for these initial evaluations because a variety of thrombosis models have been developed and are well characterized in this species, and the animals are relatively inexpensive to maintain. Because mice have a natural resistance to forming intravascular thrombi, vessel injury is required to induce intravascular clot formation. Several methods have been established for inducing arterial or venous thrombosis in mice. For the purpose of testing heparin-based drugs, we adapted a well-established model in which thrombus formation in the carotid artery is induced by exposing the vessel to ferric chloride. For studying anticoagulant effects on venous thrombosis, we use a model in which the inferior vena cava is ligated and the size of the resulting clots is measured. The most common adverse effect of anticoagulation therapy is bleeding. The effect of heparin-based anticoagulants can be tested in mice in a simple tail bleeding assay.

Topics: Animals; Anticoagulants; Chlorides; Disease Models, Animal; Ferric Compounds; Hemorrhage; Heparitin Sulfate; Mice, Inbred C57BL; Tail; Thrombosis; Vena Cava, Inferior