Structural determinants of the capacity of heparin to inhibit collagen synthesis in 21-day fetal rat calvariae

NF-kB affects migration of vascular smooth muscle cells after treatment with heparin and ibrutinib

The migration of vascular smooth muscle cells (VSMCs) is one of the most important events in the remodeling of atherosclerosis plaque. The aim of study was to investigate the role of Heparin in the VSMC migration and its association with the NF-kB, collagen 1 and collagen 3 expression levels. Moreover, the incorporation of Heparin was studied in the VSMC cultures including Betulinic acid and Ibrutinib. Twelve cell groups were cultured and treated with the Heparin, Betulinic acid and Ibrutinib based on the viability and toxicity in 24-h and 48-h periods. The gene and protein expression levels were measured by RT-qPCR and western blotting techniques. The VSMC migration was determined by scratch test. In contrast with Ibrutinib (2 μM), Heparin (30 IU) increased significantly (P < 0.05) the NF-kB gene and protein expression levels and the VSMC migration during the exposure periods. Heparin (15 IU and 30 IU) also increased the collagen 1 gene expression level in the 48-h period while Heparin (5 IU and 15 IU) increased the collagen 3 gene expression levels in both periods. Incorporating Heparin into the cultures including Betulinic acid and Ibrutinib affected the collagen 1 and collagen 3 expression levels. The data suggested that the cell migration relates to NF-kB in the VSMCs treated with Heparin and Ibrutinib. Furthermore, the Heparin doses (5 IU and 15 IU) were safe for VSMCs based on the NF-kB, and collagen 3 expression levels.

A Review of SARS-CoV2: Compared With SARS-CoV and MERS-CoV

The outbreak of coronavirus disease 2019 (COVID-19) has been spreading rapidly in China and the Chinese government took a series of policies to control the epidemic. Studies found that severe COVID-19 is characterized by pneumonia, lymphopenia, exhausted lymphocytes and a cytokine storm. Studies have showen that SARS-CoV2 has significant genomic similarity to the severe acute respiratory syndrome (SARS-CoV), which was a pandemic in 2002. More importantly, some diligent measures were used to limit its spread according to the evidence of hospital spread. Therefore, the Public Health Emergency of International Concern (PHEIC) has been established by the World Health Organization (WHO) with strategic objectives for public health to curtail its impact on global health and economy. The purpose of this paper is to review the transmission patterns of the three pneumonia: SARS-CoV2, SARS-CoV, and MERS-CoV. We compare the new characteristics of COVID-19 with those of SARS-CoV and MERS-CoV.

The Effect of Low Molecular Weight Heparins on Fracture Healing

Venous Thromboembolism is a serious complication in the trauma patient. The most commonly studied and used anticoagulant treatment in prophylaxis of thrombosis is heparin. The prolonged use of unfractionated heparin has been connected with increased incidence of osteoporotic fractures. Low molecular-weight-heparins (LMWHs) have been the golden rule in antithrombotic therapy during the previous two decades as a way to overcome the major drawbacks of unfractioned heparin. However there are few studies reporting the effects of LMWHs on bone repair after fractures. This review presents the studies about the effects of LMWHs on bone biology (bone cells and bone metabolism) and underlying the mechanisms by which LMWHs may impair fracture healing process. The authors' research based on literature concluded that there are no facts and statistics for the role of LMWHs on fracture healing process in humans and the main body of evidence of their role comes from in vitro and animal studies. Further large clinical studies designed to compare different types of LMWHs, in different dosages and in different patient or animal models are needed for exploring the effects of LMWHs on fracture healing process.

[Long-term low-molecular-weight heparin therapy during pregnancy: is there a bone risk?]

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH) are broadly used for the thromboprophylaxis during pregnancy. Long-term heparin therapy has raised concern about the risk of bone loss and osteoporotic fractures while pregnancy by itself favors osteoporosis. Experimental studies show a comparable effect of UFH and LMWH on bone formation while UFH has a more marked effect on bone resorption. Available clinical studies do not provide evidence of a difference between UFH and LMWH or among different LMWH on the bone risk. However, clinical studies show that bone loss observed with LMWH is not different from the physiological loss related to pregnancy, and osteoporotic fractures are associated with comorbidities or osteoporosis risk factors. LMWH represent the preferred alternative for thromboprophylaxis during pregnancy.

Review: Low-molecular-weight heparin-induced osteoporosis and osteoporotic fractures: a myth or an existing entity?

Long-term use of unfractioned heparin data has been associated with a 2.2-5% incidence of heparin-induced osteoporotic fracture, but for low-molecular-weight heparin (LMWH) data is scarce and there is lack of clarity of the risks of osteoporosis and osteoporotic fractures. In this paper we review the differential diagnosis of osteoporosis and osteoporotic fractures, and we conduct a systematic review of all related cases from case reports and trials. Two new cases of possible LMWH-induced osteoporosis are also presented and the difficulties in making the diagnosis are highlighted. The authors conclude that, until large clinical trials are designed to investigate pre- and post-treatment bone density and to compare different dosages of LMWH effect on the bone density in different patient groups, no safe conclusions can be made.

Effect of low molecular weight heparin (dalteparin) and fondaparinux (Arixtra) on human osteoblasts in vitro

BACKGROUND

The prolonged administration of heparin for prevention and treatment of venous thromboembolism has been associated with a risk of heparin-induced osteoporosis. Fondaparinux is a new antithrombotic drug that specifically inhibits factor Xa. Because of the known interactions of other antithrombotic agents with bone remodelling, the effects of fondaparinux on human osteoblasts were analysed in vitro.

METHODS

Primary human osteoblast cell cultures were incubated with either the low molecular weight heparin dalteparin at concentrations of 30, 300 and 900 microg/ml or with fondaparinux at concentrations of 25, 50, 100, 150, 200 and 250 microg/ml. Cellular proliferation rate and protein synthesis were measured. Expression of genes encoding osteocalcin, collagen type I and alkaline phosphatase was examined by reverse transcriptase-polymerase chain reaction.

RESULTS

Incubation with dalteparin led to a significant, dose-dependent inhibition of osteoblast proliferation, inhibition of protein synthesis, and inhibited expression of phenotype markers (osteocalcin and alkaline phosphatase genes) after 3 and 7 days. No inhibitory effects were observed in the fondaparinux-treated cells.

CONCLUSION

Fondaparinux did not inhibit osteoblast proliferation in vitro and may reduce the risk of heparin-induced osteoporosis associated with long-term heparin administration.

The effect of heparin on osteoblast differentiation and activity in primary cultures of bovine aortic smooth muscle cells

Recent studies have suggested that aortic smooth muscle cells undergo a phenotypic transition into osteoblast-like cells and mineralize when cultured in the presence of beta-glycerophosphate. Since we had previously demonstrated that heparin could inhibit osteoblast differentiation and mineralization in primary cultures of murine calvaria cells, we were interested in determining if heparin would have a similar effect when primary aortic smooth muscle cells were cultured in the presence of beta-glycerophosphate. The effect of heparin and low molecular weight heparin (LMWH) on osteoblast differentiation and activity was therefore examined in primary cultures of bovine aortic smooth muscle cells (BASMC) over a 14-day period. Here, we report that BASMC differentiate into osteoblast-like cells when cultured in the presence of beta-glycerophosphate. Moreover, we report that heparin not only inhibits this process but that it also inhibits the ability of BASMC to mineralize as well. Importantly, these effects were found not to be dependent upon heparins' anticoagulant activity since unfractionated heparin and heparins with low anti-thrombin III affinities inhibited the mineralization process equally well. Sulfation, however, was found to be a major determinant of heparins ability to inhibit BASMC mineralization since neither dermatan sulfate nor N-desulfated heparin were able to demonstrate an effect. We conclude that BASMC cultures can undergo a phenotypic transition into mature osteoblasts and that both the differentiation process and their ability to mineralize are inhibited by heparin.

The effects of enoxaparin on the reparative processes in experimental osteonecrosis of the femoral head of the rat

The blood supply of one femoral head of 6-month-old rats was severed by incising the periosteum of the neck and cutting the ligamentum teres. The rats were killed on the 30th postoperative day and the femoral bones were obtained for semiquantification of the reparative processes in the necrotic heads. Fourteen rats were treated with enoxaparin and 14 untreated animals served as controls. Statistically, the amounts of necrotic bone in the epiphysis were less, the extent of remodeling of the femoral heads was milder, and the articular cartilage degeneration was slighter in the enoxaparin-treated than untreated rats. There was no significant difference in the quantities of newly formed bone in femoral heads of treated and untreated rats. These findings are in agreement with the known effects of unfractionated and low-molecular-weight heparins which enhance osteoclastic bone resorption and angiogenesis and decrease osteoblastic bone formation. The former activities, operative in minimizing the structural distortion of the femoral head, oppose the crucial event in the pathogenesis of post-osteonecrotic osteoarthritis.

Biochemical basis of the pharmacologic action of chondroitin sulfates on the osteoarticular system

BACKGROUND

Chondroitin sulfates (CS) are involved in articular metabolism and could be used as therapeutic agents in degenerative articular diseases.

OBJECTIVES

To review the published reports describing both the metabolism of glycosaminoglycans (GAG) and their involvement in osteoarticular pathophysiology.

METHODS

MEDLINE search for relevant articles and review of cited references.

RESULTS

1) CS are formed of disaccharide units; sulfated galactosamine residues in position 4 or 6 are found in various ratios, depending on the age and the type of tissue. Binding to the core protein through N- and O-linkages leads to aggregates of monomers with high molecular weights. The proteoglycan aggregate exhibits viscoelastic and hydration properties and an ability to interact with the surrounding tissue through electric charges leading to protection of the cartilaginous tissues. 2) CS are synthesized both in chondrocytes and in bone cells by the action of specific glycosyl-transferases; their catabolism occurs in the matrix and involves numerous matrix (metalloproteinases) and lysosomal enzymes. 3) CS are inhibitors of extracellular proteases involved in the metabolism of connective tissues. In addition to their anti-inflammatory effects, CS in vitro stimulate proteoglycan production by chondrocytes; they also inhibit cartilage cytokine production and induce apoptosis of articular chondrocytes. CS increase the intrinsic viscosity of the synovial liquid. 4) In vivo in experimental arthritis, the number and severity of articular symptoms decreases after CS administration. In bones, CS accelerate the mineralization process and bone repair.

CONCLUSIONS

All these data suggest that CS play a role in articular and bone metabolism by controlling cartilaginous matrix integrity and bone mineralization.

Bone density changes in pregnant women treated with heparin: a prospective, longitudinal study

Heparin plus aspirin significantly improves the live birth rate of women with primary antiphospholipid syndrome. Osteopenia is a major concern of long-term heparin therapy. We studied prospectively the bone mineral density (BMD) changes during pregnancy and the puerperium in 123 women with primary antiphospholipid syndrome treated with low-dose aspirin and subcutaneous low-dose heparin (46 women took unfractionated heparin and 77 took low-molecular-weight heparin). Lumbar spine, neck of femur and forearm BMD were measured, using dual energy X-ray absorptiometry, at 12 weeks gestation, immediately postpartum and 12 weeks postpartum. The mean heparin duration was 27 weeks (range 22-29). During pregnancy, BMD decreased by 3.7% (P < 0.001) at the lumbar spine and by 0.9% (P < 0.05) at the neck of femur with no significant change at the forearm. Lactation was associated with a significant decrease in the lumbar spine and neck of femur BMD. There was no significant difference in BMD changes between the two heparin preparations. No woman suffered a symptomatic fracture. Long-term heparin treatment during pregnancy is associated with a small but significant decrease in BMD at the lumbar spine and neck of femur. This decrease is similar to that previously reported to occur in untreated pregnancies.

Effects of heparan-like polymers associated with growth factors on osteoblast proliferation and phenotype expression

Heparan-like polymers derived from dextran, named RGTA, were shown to stimulate bone repair in different bone defect models. Like heparin and heparan sulfates, RGTA potentiate in vitro the biological activities of heparin-binding growth factors (HBGFs), such as fibroblast growth factor (FGF), by stabilizing them against denaturations and by enhancing their binding with cellular receptors. RGTA were postulated to stimulate bone healing by interacting with HBGFs released in the wound site and, subsequently, by promoting the proliferation and/or differentiation of cells implicated in this process. We examined the effects of RGTA alone and associated with HBGFs on MC3T3-E1 osteoblastic cell proliferation and differentiation. RGTA inhibited cell proliferation, as measured by [3H]-thymidine incorporation into DNA. They enhanced the inhibition of DNA synthesis caused by transforming growth factor-beta (TGF-beta1) and bone morphogenetic protein-2 (BMP-2). RGTA alone increased the alkaline phosphatase and parathyroid hormone-responsive adenylate cyclase activities in MC3T3. RGTA enhanced the stimulation of the alkaline phosphatase activity induced by BMP-2 and decreased or suppressed the inhibition caused by TGF-beta1 and FGF-2. Furthermore, RGTA increased the response to parathyroid hormone stimulated by BMP-2. In conclusion, RGTA stimulate the expression of osteoblast phenotype features alone or in association with HBGFs. The ability to promote the differentiation of bone-forming cells is a potential explanation of the stimulating effect of RGTA on bone repair.

Hazards of heparin: allergy, heparin-induced thrombocytopenia and osteoporosis

Heparin is the commonest mode of thromboprophylaxis used in pregnancy. It does not cross the placenta but has potential adverse effects on the mother, of which the most important is heparin-induced osteoporosis. The hazards of heparin, including bleeding, skin reactions, heparin-induced thrombocytopenia and osteoporosis are discussed and the relevant literature reviewed. Low-molecular-weight heparins have certain advantages over standard unfractionated heparins, especially in obstetrics. Their longer half-life and increased bioavailability enable once-daily injections, making them more convenient and acceptable. They are as effective as standard heparin but have a theoretically more favourable side-effect profile, providing less anticoagulant relative to antithrombotic activity. Current evidence suggests a lower incidence of heparin-induced thrombocytopenia. A reduced risk of osteoporosis is suggested but not yet proven. Although thrombo-embolism is currently the leading cause of maternal mortality in the UK, antenatal heparin prophylaxis is not given to all women with previous thrombo-embolism because of continued fears concerning heparin-induced osteoporosis. A protocol is presented with guidelines for different levels of obstetric prophylaxis depending on the perceived level of risk.

A Histomorphometric Comparison of the Effects of Heparin and Low-Molecular-Weight Heparin on Cancellous Bone in Rats

Long-term heparin treatment causes osteoporosis through, an as yet, undefined mechanism. To investigate this phenomenon and to determine the relative benefits of low-molecular-weight heparin (LMWH) use, we treated rats with once daily subcutaneous injections of either unfractionated heparin (1.0 U/g or 0.5 U/g), the LMWH, Tinzaparin (1.0 U/g or 0.5 U/g), or placebo (saline) for a period of 32 days. The effects on bone were then compared both histomorphometrically and biochemically by measuring urinary type I collagen cross-linked pyridinoline (PYD) and serum alkaline phosphatase, markers of bone resorption and formation, respectively. Histomorphometric analysis of the distal third of the right femur, in the region proximal to the epiphyseal growth plate, demonstrated that both heparin and LMWH decrease cancellous bone volume in a dose-dependent fashion, but that heparin causes significantly more cancellous bone loss than does LMWH. Although both heparin and LMWH decrease osteoblast and osteoid surface to a similar extent, only heparin increases osteoclast surface. In support of these histomorphometric findings, biochemical markers of bone turnover demonstrated that both heparin and LMWH treatment produce a dose-dependent decrease in serum alkaline phosphatase, consistent with reduced bone formation, whereas only heparin causes a transient increase in urinary PYD, consistent with an increase in bone resorption. Based on these observations, we conclude that heparin decreases cancellous bone volume both by decreasing the rate of bone formation and increasing the rate of bone resorption. In contrast, LMWH, causes less osteopenia than heparin because it only decreases the rate of bone formation.

Osteoporosis and vertebral collapse following low-dose, low molecular weight heparin therapy in a young patient

Osteoporosis is a well-recognized complication of long-term heparin (unfractionated) therapy. It has been suggested that the low molecular weight heparins (LMWH) have a lower potential to cause osteopenia than the unfractionated preparations. We report a case of a 29-year-old woman who developed osteoporosis and pathological fracture of lumbar vertebrae following treatment with low dose LMWH (dalteparin) for 3 months. The aim of this report is to alert clinicians to the potential risk of this complication with the prolonged use of LMWH preparations--an increasingly popular choice for long-term anticoagulation.

Osteoporotic fractures and the recurrence of thromboembolism during pregnancy and the puerperium in 184 women undergoing thromboprophylaxis with heparin

OBJECTIVE

To study the effect of long-term treatment during gestation with heparin on the incidence of osteoporotic fractures and thromboembolic recurrence.

STUDY DESIGN

Long-term subcutaneous prophylaxis with heparin twice daily in pregnancy was prescribed for 184 women, during a decade because of an increased risk of thromboembolism. The dosage of heparin was adjusted to anti-factor Xa activity or activated partial thromboplastin time and different regimens were given, depending on the risk of recurrence.

RESULTS

For the total group the mean dosage of heparin ranged from 13,000 to 40,000 IU per 24 hours (mean 19,100 IU per 24 hours), and the average duration of treatment was 25 weeks. Symptomatic osteoporotic fractures of the spine occurred post partum in four women, for whom the mean dosage of heparin ranged from 15,000 to 30,000 IU per 24 hours (mean 24,500 IU per 24 hours), and the duration of treatment ranged from 7 to 27 weeks (mean 17 weeks). In spite of prophylaxis with heparin, thromboembolic complications occurred in five women. They had either nonsatisfactory concentrations of heparin according to our regimen or were later diagnosed as having a coagulation disorder known to increase the risk of thromboembolism.

CONCLUSION

Osteoporotic vertebral fractures were found in 2.2% of the women, and a relationship to the amount of heparin was indicated, although fractures were not avoided during low-dose, short-term prophylaxis. Recurrence of thromboembolism occurred in 2.7% of the patients, but if a strict heparin adjustment had been performed, recurrence could probably have been prevented.

Effects of heparin on osteoclast activity

The effect of heparin on osteoclastic bone resorption was studied in vitro using the disaggregated osteoclast resorption assay. Bone resorption was assessed by counting the resorption lacunae on bone slices by light microscopy. Low concentrations of heparin (5 micrograms/ml) increased bone resorption by isolated chick and rat osteoclasts. Among other glycosaminoglycans tested at 5 micrograms/ml, only dextran sulfate showed a small but significant stimulation of resorption. Chondroitin sulfates A, B, and C were without effect at 25 and 100 micrograms/ml, whereas resorption was increased by 100 micrograms/ml of heparan sulfate. With chick osteoclasts, which could be maintained in serum-free conditions, a stimulatory effect of heparin was found both in the presence of 5% fetal calf serum and in serum-free media containing insulin, transferrin, and selenium. The magnitude of the heparin-induced increase in resorption was similar in the presence or absence of serum. The stimulation of resorption was associated with an increase in the number of osteoclasts on bone slices. Pretreatment of the bone slices with heparin also enhanced resorption. In time course experiments, 5 micrograms/ml of heparin caused a doubling of chick osteoclast activity index (number of resorption pits per number of osteoclasts) at 12 and 24 h. In 24 h cultures, treatment with 10 micrograms/ml of the arginine-rich basic protein, protamine, 1 microgram/ml of the immunosuppressant, cyclosporine A, or 5 micrograms/ml of the cysteine-proteinase inhibitor, leupeptin, negated the heparin effect on bone resorption. Leupeptin also inhibited basal resorption.(ABSTRACT TRUNCATED AT 250 WORDS)