Bone metastasis and steroids are known to activate the coagulation system and induce osteoporosis, pathological bone fractures, and bone pain. Heparanase is a protein known to enhance the hemostatic system and to promote angiogenesis, metastasis, and inflammation. The objective of the present study was to evaluate the effects of steroids and malignancy on the coagulation factors and osteoblast activity in the bone tissue. The effects of dexacort and malignant medium were evaluated in osteoblasts derived from human bone marrow mesenchymal stem cells and human umbilical vein endothelial cells (HUVECs). The bones of mice treated with dexacort for 1 month were studied. Bone biopsies of ten patients with bone metastasis, ten with steroid-induced avascular necrosis (AVN), and ten with osteoarthritis were compared to ten controls. We found that dexacort and malignant medium significantly increased the heparanase levels in osteoblasts and HUVECs and decreased the levels of alkaline phosphatase (ALKP). Peptide 16AC, derived from heparanase, which interacts with tissue factor (TF), further increased the effect, while peptide 6, which inhibits interactions between heparanase and TF, reversed the effect in these cells. The bone microcirculation of mice treated with dexacort exhibited significantly higher levels of heparanase, TF, TF pathway inhibitor (TFPI), TFPI-2, thrombin, and syndecan-1, but reduced levels of osteocalcin and ALKP. The pathological human bone biopsies’ microcirculation exhibited significantly dilated blood vessels and higher levels of heparanase, TF, TFPI, TFPI-2, and fibrin. In summary, steroids and malignancy increased the activation of the coagulation system in the bone microcirculation and reduced the osteoblast activity. Heparanase inhibitors should be further investigated to attenuate bone fractures and pain.

The most common clinical presentation of hemophilia A and hemophilia B is bleeding in large joints and striated muscles. It is unclear why bleeding has a predilection to affect joints and muscles. As muscles and joints are involved in intermittent movement, we explored whether this phenomenon could be associated with an impact on factor VIII and IX levels. Purified proteins and a mouse model were assessed using coagulation assays, Western blot analysis and immuno-staining. Movement caused an increase in thrombin activity and a decrease in factor VIII and factor IX activity. The decrease in factor VIII activity was more significant in the presence of thrombin and during movement. Under movement condition, sodium ions appeared to enhance the activity of thrombin that resulted in decreased factor VIII activity. Unlike factor VIII, the reduction in factor IX levels in the movement condition was thrombin-independent. High factor VIII levels were found to protect factor IX from degradation and vice versa. In mice that were in movement, factor VIII and IX levels decreased in the microcirculation of the muscle tissue compared with other tissues and to the muscle tissue at rest. Movement had no effect on von Willebrand factor levels. Movement induces reduction in factor VIII and IX levels. It enables an increase in the binding of sodium ions to thrombin leading to enhanced thrombin activity and augmented degradation of factor VIII. These data suggest a potential mechanism underlying the tendency of hemophilia patients to bleed in muscles and joints.

Recurrent pregnancy loss (RPL) is a clinically heterogeneous reproductive disorder, and in many women the underlying mechanism remains unexplained by standard thrombophilia evaluation. Pregnancy is characterized by a tightly regulated hemostatic balance at the maternal–placental interface. Heparanase, tissue factor pathway inhibitor 2 (TFPI-2), and heparan sulfate (HS) are expressed in placental and hemostatic pathways and may contribute to coagulation-related pregnancy complications. We investigated whether the heparanase/TFPI-2/HS axis is altered in women with RPL. Blood samples were obtained from 69 women with RPL and 47 control women with at least two normal deliveries and no history of pregnancy-related vascular complications. Samples were collected at least three months after pregnancy and in the absence of hormonal therapy. Plasma and white blood cell samples were analyzed using an enzyme-linked immunosorbent assay, Western blotting, real-time polymerase chain reaction, co-immunoprecipitation, and Sanger sequencing. Mechanistic experiments using heparanase-derived peptide 16 and TFPI-2-derived peptide 6 were performed in MCF-7 and JAR cells. We found that women with RPL had increased plasma heparanase levels, heparanase procoagulant activity, HS levels, and heparanase mRNA expression compared with controls. TFPI-2 protein and mRNA expression were also elevated. The heparanase rs4693608 AA genotype was more frequent in women with RPL and, together with rs4364254 TT, was associated with increased heparanase expression and procoagulant activity. Although TFPI-2 levels were higher in RPL, co-immunoprecipitation showed reduced heparanase/TFPI-2 complex formation, suggesting impaired inhibitory regulation. HS modulated heparanase binding to TF and TFPI-2 in a concentration-dependent, bell-shaped manner. Heparanase-derived peptide 16 increased TFPI-2 expression, supporting a regulatory feedback loop. In conclusion, RPL is associated with dysregulation of the heparanase/TFPI-2/HS axis, including increased heparanase expression and activity, altered heparanase/TFPI-2 interaction, and heparanase-related genetic variation. These findings suggest a coagulation-related reproductive mechanism that may contribute to pregnancy loss and warrants validation in larger prospective studies.

Background: Hemophilia A and B induce recurrent bleeding episodes, mainly in skeletal muscles and joints that are in intermittent motion. We have previously demonstrated that intermittent motion contributes to increased degradation of factors VIII and IX. Objectives: Given that calcium ions are known to enhance factor VIII–von Willebrand factor (vWF) interaction, the present study has investigated the role of these ions on factors VIII and IX in the condition of motion. Methods: The effects of calcium ions were assessed using purified proteins via Western blot, factor VIII activity, immunocytochemistry, and in Institute of Cancer Research (ICR) mice with no specific genetic background. Results: Calcium was found to prevent degradation of plasma-derived factor VIII but not that of factor IX, during intermittent motion. Calcium levels in the microcirculation of mouse striated muscles were elevated following movement, enabling prevention of factor VIII degradation in normal physiology. Calcium supplementation in drinking water increased factor VIII levels in blood and striated muscles of ICR mice during movement. Conclusions: calcium ions decrease factor VIII degradation in the condition of motion. Further research on the impact of calcium salt oral supplementation on hemophilia patients is warranted.