The effects of heparin and low molecular weight heparins on bone

Heparinase III with High Activity and Stability: Heterologous Expression, Biochemical Characterization, and Application in Depolymerization of Heparin

A novel heparinase III from Pedobacter schmidteae (PsHep-III) with high activity and good stability was successfully cloned, expressed, and characterized. PsHep-III displayed the highest specific activity ever reported of 192.8 U mg-1 using heparin as the substrate. It was stable at 25 °C with a half-life of 323 h in an aqueous solution. PsHep-III was employed for the depolymerization of heparin, and the enzymatic hydrolyzed products were analyzed with gel permeation chromatography and high-performance liquid chromatography. PsHep-III can break glycosidic bonds in heparin like →4]GlcNAc/GlcNAc6S/GlcNS/GlcNS6S/GlcN/GlcN6S(1 → 4)ΔUA/ΔUA2S[1 → and efficiently digest heparin into seven disaccharides including N-acetylated, N-sulfated, and N-unsubstituted modification, with molecular masses of 503, 605, 563, 563, 665, 360, and 563 Da, respectively. These results indicated that PsHep-III with broad substrate specificity could be combined with heparinase I to overcome the low selectivity at the N-acetylated modification binding sites of heparinase I. This work will contribute to the application of PsHep-III for characterizing heparin and producing low-molecular-weight heparin effectively.

Not Just Anticoagulation—New and Old Applications of Heparin

In recent decades, heparin, as the most important anticoagulant drug, has been widely used in clinical settings to prevent and treat thrombosis in a variety of diseases. However, with in-depth research, the therapeutic potential of heparin is being explored beyond anticoagulation. To date, heparin and its derivatives have been tested in the protection against and repair of inflammatory, antitumor, and cardiovascular diseases. It has also been explored as an antiangiogenic, preventive, and antiviral agent for atherosclerosis. This review focused on the new and old applications of heparin and discussed the potential mechanisms explaining the biological diversity of heparin.

Impaired bone healing by enoxaparin via inhibiting the differentiation of bone marrow mesenchymal stem cells towards osteoblasts

INTRODUCTION

Enoxaparin is widely used to prevent venous thromboembolism after orthopedic surgery and has some adverse effects, such as osteoporosis and delay in fracture healing. However, the exact mechanism delaying bone healing by enoxaparin is still unclear.

MATERIALS AND METHODS

X-ray and Micro-CT scanning were performed to detect the effects of enoxaparin on bone healing at rat model of bone defeat. CCK-8 assay and flow cytometry were conducted to measure the effects of enoxaparin on bone marrow mesenchymal stem cells (BMSCs). The mRNA/protein levels of osteocalcin (OCN), runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 2 (BMP2) were analyzed by real-time PCR and western blotting, respectively. Alizarin red staining was used to observe the mineralized nodules.

RESULTS

Enoxaparin (2000 AXaIU/kg) not only profoundly increased the trabecular separation, but also notably decreased the trabecular bone volume/tissue volume, trabecular thickness, trabecular number and OCN level, in vivo. Additionally, significantly inhibiting proliferation of BMSCs by enoxaparin (1.0 and 10 AXaIU/ml) was detected. The apoptosis and the ratio of G phase cells in enoxaparin (0.1, 1.0 and 10 AXaIU/ml) group were obviously higher than that in control group. While the ratio of S phase cells was downregulated markedly by enoxaparin (0.1,1.0 and 10 AXaIU/ml) compared with the control group. Most importantly, inducing significant decreases of OCN/Runx2 mRNA/protein expression and formation of mineralized nodules by enoxaparin (0.1, 1.0 and 10 AXaIU/ml) were observed compared with the control group. While the notable decreases of BMP2 mRNA/protein level were only detected in enoxaparin (10 AXaIU/ml) group.

CONCLUSION

It was suggested that enoxaparin impaired bone healing through suppressing the differentiation of BMSCs towards osteoblasts.

Glycosaminoglycan content of a mineralized collagen scaffold promotes mesenchymal stem cell secretion of factors to modulate angiogenesis and monocyte differentiation

Effective design of biomaterials to aid regenerative repair of craniomaxillofacial (CMF) bone defects requires approaches that modulate the complex interplay between exogenously added progenitor cells and cells in the wound microenvironment, such as osteoblasts, osteoclasts, endothelial cells, and immune cells. We are exploring the role of the glycosaminoglycan (GAG) content in a class of mineralized collagen scaffolds recently shown to promote osteogenesis and healing of craniofacial bone defects. We previously showed that incorporating chondroitin-6-sulfate or heparin improved mineral deposition by seeded human mesenchymal stem cells (hMSCs). Here, we examine the effect of varying scaffold GAG content on hMSC behavior, and their ability to modulate osteoclastogenesis, vasculogenesis, and the immune response. We report the role of hMSC-conditioned media produced in scaffolds containing chondroitin-6-sulfate (CS6), chondroitin-4-sulfate (CS4), or heparin (Heparin) GAGs on endothelial tube formation and monocyte differentiation. Notably, endogenous production by hMSCs within Heparin scaffolds most significantly inhibits osteoclastogenesis via secreted osteoprotegerin (OPG), while the secretome generated by CS6 scaffolds reduced pro-inflammatory immune response and increased endothelial tube formation. All conditioned media down-regulated many pro- and anti-inflammatory cytokines, such as IL6, IL-1β, and CCL18 and CCL17 respectively. Together, these findings demonstrate that modifying mineralized collagen scaffold GAG content can both directly (hMSC activity) and indirectly (production of secreted factors) influence overall osteogenic potential and mineral biosynthesis as well as angiogenic potential and monocyte differentiation towards osteoclastic and macrophage lineages. Scaffold GAG content is therefore a powerful stimulus to modulate reciprocal signaling between multiple cell populations within the bone healing microenvironment.

Osteogenic and Angiogenic Properties of Heparin as a System for Delivery of Biomolecules for Bone Bioengineering: a Brief Critical Review

The review considers complex, controversial, and individual effects of heparin and its derivatives on the bone and circulatory systems in dependence of the dose, the state of the cells and tissues of the recipient. General data on the anticoagulant activity of heparin and its derivatives are presented; special attention is paid to the effect of heparin on mesenchymal cells and tissues and its role in angiogenesis. We also discuss the ability of heparin to bind osteogenic and angiogenic biomolecules in the context of the development of systems for their delivery and sustained controlled release and propose a schematic representation of the positive and side effects of heparin as a delivery system for biomolecules in tissue engineering.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

[Osteogenic and angiogenic properties of heparin as a system of biomolecule delivery for bone bioengineering: a brief critical review]

The review discusses the complex, ambiguous and individual effects of heparin and its derivatives on the bone and circulatory systems, in dependence of the dosage, the state of the cells and tissues of recipients. General data on the anticoagulant activity of heparin and its derivatives are presented; aspects of the effect of heparin on mesenchymal cells and tissues and its role in angiogenesis are considered in details. Particular attention is paid to the ability of heparin to bind osteogenic and angiogenic biomolecules: thus us especially important for the development of systems for their delivery and sustained controlled release. A schematic representation of the positive and side effects of heparin as a delivery system for biomolecules in tissue engineering is proposed.

Comprehensive Landscape of Heparin Therapy for COVID-19

The pandemic coronavirus disease 2019 (COVID-19), caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is rapidly spreading globally. Clinical observations found that systemic symptoms caused by SARS-CoV-2 infection are attenuated when using the anticoagulant agent heparin, indicating that heparin may play other roles in managing COVID-19, in addition to prevention of pulmonary thrombosis. Several biochemical studies show strong binding of heparin and heparin-like molecules to the Spike protein, which resulted in inhibition of viral infection to cells. The clinical observations and in vitro studies argue for a potential multiple-targeting effects of heparin. However, adverse effects of heparin administration and some of the challenges using heparin therapy for SARS-CoV-2 infection need to be considered. This review discusses the pharmacological mechanisms of heparin regarding its anticoagulant, anti-inflammatory and direct antiviral activities, providing current evidence concerning the effectiveness and safety of heparin therapy for this major public health emergency.

Cancer-associated thrombosis in pediatric patients

Childhood malignancy and especially acute lymphoblastic leukemia are increasingly associated with thromboembolism. The etiology of pediatric cancer associated thrombosis is multifactorial and may reflect a tumor mass effect, tumor thrombi, alterations of the hemostatic system, treatment-related hazards (e.g. procoagulant changes induced by chemotherapy), presence of central venous lines and comorbidities (e.g. inherited thrombophilia). With over 80% cure rates of childhood cancer, strategies for prevention as well as for early diagnosis and optimal treatment of thromboembolism in children with malignancies are of major importance. While the use of therapeutic low molecular weight heparin prevails, prospective studies regarding guidelines for treatment or prevention are currently lacking. This review will address the epidemiology, etiology and risk factors for thrombosis, describe the presently available evidence associated with current therapy, and offer a glimpse into future treatment options.

FondaKIDS III: A long-term retrospective cohort study of fondaparinux for treatment of venous thromboembolism in children

BACKGROUND

The incidence of venous thromboembolism (VTE) and use of anticoagulation are rising in children, but treatment options remain limited. As a newer anticoagulant, fondaparinux may be a safe and effective alternative with the benefit of once-daily dosing, but there is relatively little data supporting its use.

PROCEDURE

This retrospective cohort study describes the long-term dosing, efficacy, and safety of fondaparinux for treatment of VTE in children at a single institution. The study included children <18 years old treated with fondaparinux for VTE between 2008 and 2018. Descriptive statistics were used to present the findings.

RESULTS

A total of 277 patients were identified and analyzed in this study. Seventy-six percent of patients reached therapeutic levels with 0 or 1 dose adjustments over a median treatment duration of 93 days. Of the patients included in the efficacy analysis, 91% of patients had improvement in their clot status, including 69% (160/233) with complete resolution and 22% (53/233) with partial resolution. Twenty-six patients (11%) had VTE recurrence, but only seven (3%) of the new thrombi developed while on fondaparinux. Major bleeding occurred in seven patients (2.5%), primarily in patients with underlying medical conditions with increased bleeding risk. Minor bleeding occurred in 53 patients (19%).

CONCLUSIONS

This study demonstrates the stable long-term pediatric dosing of fondaparinux with similar efficacy and safety when compared to other anticoagulants. Given its advantages, fondaparinux can be considered a reasonable alternative for treatment of VTE in children.

[Periprosthetic fractures of the acetabulum: osteosynthesis]

In most cases periprosthetic fractures of the acetabulum are complex injuries and are extremely challenging for the treating medical team. Over the years the frequency of this overall rare entity has increased due to demographic changes. In recent years several treatment algorithms were published and provided the possibility of developing standardized treatment concepts. The classification of the fractures and a dedicated preoperative strategy are highly important for the quality of patient-centered care. In the literature the frequency of intraoperative fractures was initially given as 0.4%; however, several studies have been published in which a far higher rate of intraoperative fractures was detected by computed tomography (CT), often referred to as so-called occult fractures. The causes are multifactorial and there is significant association with whether cement-free press-fit acetabular cups were used or cemented forms. In approximately 75% of the cases a low energy impact was the cause of the fracture. In these patients systemic processes, such as osteoporotic alterations of the bony substance or the possible presence of low-grade infections should be considered. This article gives an overview of the diagnostics, planning, challenges and osteosynthetic treatment options for periprosthetic fractures of the acetabulum.

Effect of long-term use of unfractionated or low-molecular-weight heparin on bone mineral density in maintenance hemodialysis patients

Introduction

Long‐term use of unfractionated heparin (UFH) or low‐molecular‐weight heparin (LMWH) causes bone loss and osteoporosis in patients not receiving hemodialysis. This study aimed to investigate the effect of UFH and LMWH on bone mineral density (BMD) in patients undergoing maintenance hemodialysis (MHD).

Methods

Patients undergoing MHD using UFH or LMWH as anticoagulants were enrolled. BMD (in g/cm²), T‐score and Z‐score (BMDs) were measured at the lumbar spine and femur neck using dual‐energy X‐ray absorptiometry (DXA) at baseline and 2 years later. Patient demographics and clinical indices were collected. Correlation analysis was used to identify significant predictors of bone loss. Multiple linear regression was used to explore the relationship between heparin type and bone loss progression.

Findings

A total of 104 patients were enrolled and completed the baseline BMD test; 72 completed the test again 2 years later. Six patients were excluded because they used both UFH and LMWH. Although BMD decreased in some patients in the UFH group, a slight increase in the BMD was observed on an average in the LMWH group after 2 years. The mean change in BMD (in g/cm²) [0(−0.03,0.04) vs. 0.04(0,0.06), P = 0.023], T‐score [0(−0.40,0.30) vs. 0.35(−0.03,0.53), P = 0.038], and Z‐score [0.10(−0.30,0.40) vs. 0.45(0.08,0.63), P = 0.031] in the lumbar spine in the UFH group was lower than those in the LMWH group. Femur neck BMD did not change significantly. In a linear regression model, after adjusting for diabetes mellitus, parathyroid hormone, and serum phosphate, we did not find an association between heparin substances and BMD.

Discussion

UFH might be associated with loss of lumbar spine BMD in patients undergoing MHD.

Glycosaminoglycans bind human IL-27 and regulate its activity

IL-27 is a cytokine of the IL-12 family, composed of EBI3 and IL-27p28. IL-27 regulates immune responses and also other physiological processes including hematopoiesis, angiogenesis, and bone formation. Its receptor, composed of IL-27Rα and gp130, activates the STAT pathway. Here, we show that different glycosaminoglycans (GAGs) modulate human IL-27 activity in vitro. We find that soluble heparin and heparan sulfate efficiently inhibit human IL-27 activity as shown by decreased STAT signaling and downstream biological effects. In contrast, membrane-bound heparan sulfate seems to positively regulate IL-27 activity. Our biochemical studies demonstrate that soluble GAGs directly bind to human IL-27, consistent with in silico analyses, and prevent its binding to IL-27Rα. Although murine IL-27 also bound to GAGs in vitro, its activity was less efficiently inhibited by soluble GAGs. Lastly, we show that two heparin-derivatives, low molecular weight heparin and fondaparinux, that like unfractionated heparin are used in clinics, had weaker or no effect on human IL-27 activity. Together, our data identify GAGs as new players in the regulation of human IL-27 activity that might act under physiological conditions and may also have a clinical impact in heparin-treated patients.

Anisotropic mineralized collagen scaffolds accelerate osteogenic response in a glycosaminoglycan-dependent fashion

Regeneration of critically-sized craniofacial bone defects requires a template to promote cell activity and bone remodeling. However, induced regeneration becomes more challenging with increasing defect size. Methods of repair using allografts and autografts have inconsistent results, attributed to age-related regenerative capabilities of bone. We are developing a mineralized collagen scaffold to promote craniomaxillofacial bone regeneration as an alternative to repair. Here, we hypothesize modifying the pore anisotropy and glycosaminoglycan content of the scaffold will improve cell migration, viability, and subsequent bone formation. Using anisotropic and isotropic scaffold variants, we test the role of pore orientation on human mesenchymal stem cell (MSC) activity. We subsequently explore the role of glycosaminoglycan content, notably chondroitin-6-sulfate, chondroitin-4-sulfate, and heparin sulfate on mineralization. We find that while short term MSC migration and activity was not affected by pore orientation, increased bone mineral synthesis was observed in anisotropic scaffolds. Further, while scaffold glycosaminoglycan content did not impact cell viability, heparin sulfate and chondroitin-6-sulfate containing variants increased mineral formation at the late stage of in vitro culture, respectively. Overall, these findings show scaffold microstructural and proteoglycan modifications represent a powerful tool to improve MSC osteogenic activity.

Mineralized collagen scaffolds were modified to include anisotropic pore architecture and one of three glycosaminoglycans in order to improve bone mineral formation in vitro.

Efficacy and safety of the injection of the traditional Chinese medicine salviae miltiorrhizae and ligustrazine hydrochloride for the treatment of perioperative period of fracture: A meta-analysis of randomized controlled trials

BACKGROUND

The injection of the traditional Chinese patent medicine salviae miltiorrhizae and ligustrazine hydrochloride injection (SMLHI) has been widely used in treatment of various diseases such as angina pectoris or ischemic stroke in China. We aim to evaluate the efficacy and safety of SMLHI for the treatment of perioperative period of fracture.

METHODS

A systematic literature search was performed in seven medical databases from their inception until February 2019. 16 studies with randomized controlled trials, totaling 1589 patients, were included in this meta-analysis. The included studies were assessed by the cochrane risk of bias and analyzed by Review Manager 5.3 software.

RESULTS

The meta-analysis showed that SMLHI for the treatment of perioperative period of fracture was significantly better compared with the control group in terms of the total effective rate. The result showed that SMLHI could significantly reduce the risk of deep vein thrombosis and inflammatory cytokines. Furthermore, the result showed that SMLHI could significantly improve the coagulation function indexes such as prothrombin time, plasma fibrinogen and D-Dimer (P < .0001).

CONCLUSIONS

This meta-analysis demonstrated that SMLHI may be more effective and safe for the treatment of perioperative period of fracture. However, further and higher quality randomized controlled trials are required to prove treatment outcome.

Anticoagulants and Osteoporosis

Anticoagulant agents are widely used in the treatment of thromboembolic events and in stroke prevention. Data about their effects on bone tissue are in some cases limited or inconsistent (oral anti-vitamin K agents), and in others are sufficiently strong (heparins) to suggest caution in their use in subjects at risk of osteoporosis. This review analyses the effects of this group of drugs on bone metabolism, on bone mineral density, and on fragility fractures. A literature search strategy was developed by an experienced team of specialists by consulting the MEDLINE platform, including published papers and reviews updated to March 2019. Literature supports a detrimental effect of heparin on bone, with an increase in fracture rate. Low molecular weight heparins (LMWHs) seem to be safer than heparin. Although anti-vitamin K agents (VKAs) have a significant impact on bone metabolism, and in particular, on osteocalcin, data on bone mineral density (BMD) and fractures are contrasting. To date, the new direct oral anticoagulants (DOACs) are found to safe for bone health.

Novel insights into the complex architecture of osteoporosis molecular genetics

Osteoporosis is a prevalent osteodegenerative disease and silent killer linked to a decrease in bone mass and decline of bone microarchitecture, due to impaired bone matrix mineralization, raising the risk of fracture. Nevertheless, the process of bone matrix mineralization is still an unsolved mystery. Osteoporosis is a polygenic disorder associated with genetic and environmental risk factors; however, the majority of genes associated with osteoporosis remain largely unknown. Several signaling pathways regulate bone mass; therefore, dysregulation of a single signaling pathway leads to metabolic bone disease owing to high or low bone mass. Parathyroid hormone, core-binding factor α-1 (Cbfa1), Wnt/β-catenin, the receptor activator of the nuclear factor kappa-B (NF-κB) ligand (RANKL), myostatin, and osteogenic exercise signaling pathways play pivotal roles in the regulation of bone mass. The myostatin signaling pathway increases bone resorption by activating the RANKL signaling pathway, whereas osteogenic exercise inhibits myostatin and sclerostin while inducing irisin that consequentially activates the Cbfa1 and Wnt/β-catenin bone formation pathways. The aims of this review are to summarize what is known about osteoporosis-related signaling pathways; define the role of these pathways in osteoporosis drug discovery; focus light on the link between bone, muscle, pancreas, and adipose integrative physiology and osteoporosis; and underline the emerging role of osteogenic exercise in the prevention of, and care for, osteoporosis, obesity, and diabetes.

Different type and dosage of heparin were not associated with the progression of coronary artery calcification in haemodialysis patients

AIM

Several studies have verified that unfractionated heparin (UFH) and low molecular heparin (LWMH) can induce bone loss, and bone mineral density has been inversely associated with vascular calcification in some clinical researches. But few have focused on the relationship between types and dosages of heparin and the progression of vascular calcification. We observed the progression of coronary artery calcification (CAC) in maintenance haemodialysis (MHD) patients who were treated with UFH and LMWH.

METHODS

This was a prospective prevalent cohort study of MHD patients. Computed tomography was performed at enrolment and 2 years after enrolment, and CAC score was obtained. Demographic and clinical data, baseline and time-average laboratory indices were collected. Multiple linear regression and logistic regression were used to estimate the influencing factors of progression of CAC.

RESULTS

In this study, (i) we initially enrolled 69 HD patients, and then 56 patients finished the follow-up. (ii) Among the total 56 patients, 27 patients (48.2%) were treated with UFH, 14 (25.0%) with LMWH and 15 (26.8%) with both. The median baseline CAC scores of three groups (UFH, LMWH and both users) were 91.0 (1.0, 1052.0), 134.0 (0, 1292.0) and 250.5 (27.0, 1139.0), respectively, with no significant difference (P = 0.663); the median CAC progression scores were 42.0 (0, 364.0), 172.0 (7.0, 653.0) and 118.5 (0, 434.0), respectively, with no significant difference (P = 0.660). (iii) Pearson and spearman correlation analysis shown that the progression of CAC was not associated with cumulative dosage of heparin used. (iv) After adjusted for diabetes mellitus, time-averaged intact parathyroid hormone, phosphate and alkaline phosphatase, logistic regression analysis showed using different types of heparin was not an independent risk factor for CAC progression; and multiple linear regression analysis showed that the type of heparin used was not associated with CAC progression.

CONCLUSION

There were no significant differences in the effects of the types and dosages of heparin on CAC progression in patients on haemodialysis.

Evaluation of anticoagulant agents for the treatment of human metapneumovirus infection in mice

Thrombin has been demonstrated to be involved in several viral diseases including human metapneumovirus (hMPV) infections. We previously showed that immediate administration of thrombin inhibitor argatroban post-infection protected mice against hMPV disease. This current work aims at determining whether warfarin and heparin, two other anticoagulants inhibiting thrombin formation and activities, may also be used for treatment against hMPV in vivo. We found that immediate injections of argatroban, warfarin or heparin after virus challenge protected mice against hMPV infection, as evidenced by decreased or no mortality, less weight loss, reduced viral load and attenuated inflammation. However, delayed treatments starting 1 day post-infection with argatroban or warfarin almost did not impact the survival whereas delayed treatment with heparin induced an increased mortality during infection. Moreover, these treatments also did not reduce weight loss, viral replication and inflammation. In agreement with these results, thrombin generation was decreased upon immediate anticoagulant treatments but was unaltered upon delayed treatments. Thus, thrombin generation occurs at the onset of hMPV infection and thrombin inhibition may be only useful for the treatment of this disease when initiated in the early stage. In this case, heparin is not recommended because of its reduced efficacy on mortality in infected mice whereas argatroban and warfarin appear as safe and effective drugs for the treatment of hMPV disease. The antiviral and anti-inflammatory effects of argatroban occur via thrombin-dependent pathways whereas the mechanisms by which warfarin exerts its beneficial effects against hMPV infection were not elucidated and need to be further studied.

Antiplatelet and anticoagulant agents for primary prevention of thrombosis in individuals with antiphospholipid antibodies

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disease characterised by the presence of antiphospholipid (aPL) antibodies that have prothrombotic activity. Antiphospholipid antibodies are associated with an increased risk of pregnancy complications (recurrent miscarriage, premature birth, intrauterine growth retardation) and thrombotic events (both arterial and venous). The most common thrombotic events include brain ischaemia (stroke or transient ischaemic attack) and deep vein thrombosis. To diagnose APS, the presence of aPL antibodies in two measurements and at least one thrombotic event or pregnancy complication are required. It is unclear if people with positive aPL antibodies but without any previous thrombotic events should receive primary antithrombotic prophylaxis.

OBJECTIVES

To assess the effects of antiplatelet or anticoagulant agents versus placebo or no intervention or other intervention on the development of thrombosis in people with aPL antibodies who have not had a thrombotic event. We did not address obstetric outcomes in this review as these have been thoroughly addressed by other Cochrane Reviews.

SEARCH METHODS

We searched the Cochrane Vascular Specialised Register (4 December 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (last search 29 November 2017), MEDLINE Ovid, Embase Ovid, CINAHL, and AMED (searched 4 December 2017), and trials registries (searched 29 November 2017). We also checked reference lists of included studies, systematic reviews, and practice guidelines, and contacted experts in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any antiplatelet or anticoagulant agents, or their combinations, at any dose and mode of delivery with placebo, no intervention, or other intervention. We also included RCTs that compared antiplatelet or anticoagulant agents with each other or that compared two different doses of the same drug. We included studies performed in people of any age and with no history of thrombosis (as defined by APS Sapporo classification criteria or updated Sydney classification criteria), but with aPL antibodies confirmed on at last two separate measurements. The studies included both pregnant women who tested positive for aPL antibodies and had a history of recurrent obstetric complications, as well as non-pregnancy related cases with positive screening for antibodies, in accordance with the criteria mentioned above.

DATA COLLECTION AND ANALYSIS

Pairs of authors independently selected studies for inclusion, extracted data, and assessed the risk of bias for the included studies and quality of evidence using GRADE. Any discrepancies were resolved through discussion or by consulting a third review author when necessary. In addition, one review author checked all the extracted numerical data.

MAIN RESULTS

We included nine studies involving 1044 randomised participants. The studies took place in several countries and had different funding sources. No study was at low risk of bias in all domains. We classified all included studies as at unclear or high risk of bias in two or more domains. Seven included studies focused mainly on obstetric outcomes. One study included non-pregnancy-related cases, and one study included both pregnancy-related cases and other patients with positive results for aPL antibodies. The remaining studies concerned women with aPL antibodies and a history of pregnancy failure. Four studies compared anticoagulant with or without acetylsalicylic acid (ASA) versus ASA only and observed no clear difference in thrombosis risk (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.25 to 3.77; 4 studies; 493 participants; low-quality evidence). No major bleeding was reported, but minor bleeding risk (nasal bleeding, menorrhagia) was higher in the anticoagulant with ASA group as compared with ASA alone in one study (RR 22.45, 95% CI 1.34 to 374.81; 1 study; 164 participants; low-quality evidence). In one study ASA was compared with placebo, and there were no clear differences in thrombosis (RR 5.21, 95% CI 0.63 to 42.97; 1 study; 98 participants; low-quality evidence) or minor bleeding risk between the groups (RR 3.13, 95% CI 0.34 to 29.01; 1 study; 98 participants; low-quality evidence), and no major bleeding was observed. Two studies compared ASA with low molecular weight heparin (LMWH) versus placebo or intravenous immunoglobulin (IVIG), and no thrombotic events were observed in any of the groups. Moreover, there were no clear differences in the risk of bleeding requiring transfusion (RR 9.0, 95% CI 0.49 to 164.76; 1 study; 180 participants; moderate-quality evidence) or postpartum bleeding (RR 1.30, 95% CI 0.60 to 2.81; 1 study; 180 participants; moderate-quality evidence) between the groups. Two studies compared ASA with high-dose LMWH versus ASA with low-dose LMWF or unfractionated heparin (UFH); no thrombotic events or major bleeding was reported. Mortality and quality of life data were not reported for any of the comparisons.

AUTHORS' CONCLUSIONS

There is insufficient evidence to demonstrate benefit or harm of using anticoagulants with or without ASA versus ASA alone in people with aPL antibodies and a history of recurrent pregnancy loss and with no such history; ASA versus placebo in people with aPL antibodies; and ASA with LMWH versus placebo or IVIG, and ASA with high-dose LMWH versus ASA with low-dose LMWH or UFH, in women with aPL antibodies and a history of recurrent pregnancy loss, for the primary prevention of thrombotic events. In a mixed population of people with a history of previous pregnancy loss and without such a history treated with anticoagulant combined with ASA, the incidence of minor bleeding (nasal bleeding, menorrhagia) was increased when compared with ASA alone. Studies that are adequately powered and that focus mainly on thrombotic events are needed to draw any firm conclusions on the primary prevention of thrombotic events in people with antiphospholipid antibodies.

Combined pharmacotherapy for osteonecrosis of the femoral head after severe acute respiratory syndrome and interstitial pneumonia: two and a half to fourteen year follow-up

PURPOSE

The purpose of this study was to retrospectively analyze the clinical, functional, and radiological outcomes of combined pharmacotherapy to ONFH after high-dose corticosteroid therapy.

METHOD

From August 2003 to June 2015, five patients (ten hips) of ONFH in ARCO stage I, after SARS and Interstitial pneumonia, were treated by combined pharmacotherapy. Lipo-prostaglandin E₁ 10 μg iv Bid × 28 days, enoxaparin 6000 iu H QD × 12 weeks, alendronate sodium tablet 10 mg QD × 1 year. The patients were fully weight-bearing following completion of the follow-up.

RESULT

For these five patients (ten hips), Harris score was 100 from the diagnosis to final follow-up time. Radiologic findings show no signs of collapse, necrotic focus was repaired, and ARCO stages were changed from I_C into II_B.

CONCLUSION

This combined pharmacotherapy has promising treatment results for delaying or preventing collapse of ONFH in ARCO stage I.

Deep vein thrombosis in pediatric patients

Due to advances in caring for critically ill children and those with chronic diseases, rates of deep vein thrombosis (DVT) are increasing in children. Risk factors consist of central venous catheters, chronic medical conditions, thrombophilia, and various medications. Compression Doppler ultrasonography is the method most commonly used to diagnose DVT, and patients will usually present with pain and swelling of the affected limb. Anticoagulation via subcutaneous injection is the most common treatment regime for children with DVT, and the new, direct oral anticoagulants are currently under investigation. Prevention techniques are not established, but clinical studies are addressing this need.

Anticoagulation Therapies in Children

Venous thromboembolism is occurring with increasing frequency in children resulting in the more widespread use of anticoagulation in pediatrics. Antithrombotic drugs in children can be divided into the standard and alternative agents. This review discusses standard and alternative anticoagulants. Because standard anticoagulants have significant limitations, including variable pharmacokinetics, issues with therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects, it is expected that the use of alternative anticoagulants will increase over time. With their improved properties and recent prospective clinical trial data, the current and future use of these agents will likely slowly replace of the standard anticoagulants.

Modulation of the Plasma Kallikrein-Kinin System Proteins Performed by Heparan Sulfate Proteoglycans

Human plasma kallikrein-kinin system proteins are related to inflammation through bradykinin. In the proximity of its target cells, high molecular weight kininogen (H-kininogen) is the substrate of plasma kallikrein, which releases bradykinin from H-kininogen. Heparan sulfate proteoglycans (HSPGs) play a critical role in either recruiting kinin precursors from the plasma, or in the assembly of kallikrein-kinin system components on the cell surface. Furthermore, HSPGs mediate the endocytosis and activation of H-kininogen and plasma prekallikrein. In the presence of HSPGs (Chinese hamster ovary cell, CHO-K1, wild type cells) both heparin and heparan sulfate strongly inhibit the H-kininogen interaction with the cell membrane. H-kininogen is internalized in endosomal acidic vesicles in CHO-K1 but not in CHO-745 cells (mutant cells deficient in glycosaminoglycan biosynthesis). The endocytosis process is lipid raft-mediated and is dependent on caveolae. Both types of CHO cells do not internalize bradykinin-free H-kininogen. At pH 7.35, bradykinin is released from H-kininogen on the surface of CHO-745 cells only by serine proteases; however, in CHO-K1 cells either serine or cysteine proteases are found to be involved. The CHO-K1 cell lysate contains different kininogenases. Plasma prekallikrein endocytosis in CHO-K1 cells is independent of H-kininogen, and also prekallikrein is not internalized by CHO-745 cells. Plasma prekallikrein cleavage/activation is independent of glycosaminoglycans but plasma kallikrein formation is more specific on H-kininogen assembled on the cell surface through glycosaminoglycans. In this mini-review, the importance of HSPGs in the regulation of plasma kallikrein-kinin system proteins is shown.

Osteoblastic heparan sulfate glycosaminoglycans control bone remodeling by regulating Wnt signaling and the crosstalk between bone surface and marrow cells

Stimulating bone formation is an important challenge for bone anabolism in osteoporotic patients or to repair bone defects. The osteogenic properties of matrix glycosaminoglycans (GAGs) have been explored; however, the functions of GAGs at the surface of bone-forming cells are less documented. Syndecan-2 is a membrane heparan sulfate proteoglycan that is associated with osteoblastic differentiation. We used a transgenic mouse model with high syndecan-2 expression in osteoblasts to enrich the bone surface with cellular GAGs. Bone mass was increased in these transgenic mice. Syndecan-2 overexpression reduced the expression of receptor activator of NF-kB ligand (RANKL) in bone marrow cells and strongly inhibited bone resorption. Osteoblast activity was not modified in the transgenic mice, but bone formation was decreased in 4-month-old transgenic mice because of reduced osteoblast number. Increased proteoglycan expression at the bone surface resulted in decreased osteoblastic and osteoclastic precursors in bone marrow. Indeed, syndecan-2 overexpression increased apoptosis of mesenchymal precursors within the bone marrow. However, syndecan-2 specifically promoted the vasculature characterized by high expression of CD31 and Endomucin in 6-week-old transgenic mice, but this was reduced in 12-week-old transgenic mice. Finally, syndecan-2 functions as an inhibitor of Wnt-β-catenin–T-cell factor signaling pathway, activating glycogen synthase kinase 3 and then decreasing the Wnt-dependent production of Wnt ligands and R-spondin. In conclusion, our results show that GAG supply may improve osteogenesis, but also interfere with the crosstalk between the bone surface and marrow cells, altering the supporting function of osteoblasts.

Agent specific effects of anticoagulant induced alopecia

Alopecia has been observed with many anticoagulants although the mechanism is unclear. A 20 year old female with recurrent DVTs developed alopecia with multiple anticoagulants, including heparin derivatives and the new oral anticoagulants. This resolved with discontinuation of the agents. The patient was ultimately able to be anticoagulated with fondaparinux long term without any alopecia. This case addresses the Key Clinical Question of management and recognition of anticoagulant induced alopecia. This side effect can result from almost any of the available agents and is quickly reversible, underlining the importance of tailoring treatment to the individual and their experiences.

Anticoagulation in children: Making the most of little patients and little evidence

Thrombotic complications are increasing at a steady and significant rate in children resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the standard agents (heparin, low molecular weight heparin, and vitamin K antagonists) and alternative agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the standard and alternative anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. Clearly, the standard anticoagulants all have significant shortcomings including variable pharmacokinetics, issues with therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The alternative anticoagulants have properties which overcome these shortcomings and prospective clinical trial data are presented supporting the current and future use of these agents in place of the standard anticoagulants.

Periodontal and biochemical bone metabolism assessment on a chronic oral anticoagulation population treated with dicoumarins

BACKGROUND

The aim is to evaluate periodontal alteration and biochemical markers associated with bone turnover in chronic oral with dicoumarins anticoagulant treatment patients.

MATERIAL AND METHODS

80 patients treated with oral anticoagulants were divided into 2 cohort: Group A (n=36) 6 month to 1 year with anticoagulant treatment and Group B (n=44) > 2 years with anticoagulant treatment. Clinical evaluation included: Clinical attachment level (CAL), plaque index (PI) and gingival index (GI). Analytically biochemical parameters of bone remodeling (calcium and phosphorus), formation (total acid phosphatase, alkaline phosphatase and osteocalcin) and resorption (tartrate-resistant acid phosphatase and beta-crosslaps) were evaluated.

RESULTS

High values of PI (67-100%) especially in men and in Group B were observed. Men with anticoagulation treatment length showed an increased GI (49.167 vs 78.083) while Group B women showed a decreased GI in comparison with Group A (59.389 vs 42.120). Women presented a greater average CAL than men as well as Group B vs Group A but without statistical significance. All biochemical markers were decreased respect to values of general population. Osteocalcin in GroupB women showed a statistically significant outcome vs GroupA (p=0.004). Acid phosphatase (total and tartrate-resistant) has a slight increase in Group B women versus Group A, and Beta-crosslap showed lower values in Group A men than Group B and slightly lower in Group A women versus Group B, without statistical significance.

CONCLUSIONS

Patients showed a slight to moderate degree of periodontal affectation, especially gingivitis related to bacterial plaque. Periodontal disorders tended to be more severe in Group B. While bone remodeling showed an overall decrease with greater affectation of bone neoformation phenomena, bone destruction tended to recover and normalize in time.

How We Manage Pediatric Deep Venous Thrombosis

Over the past two decades, the incidence and recognition of venous thromboembolism (VTE) in children has significantly increased, likely as a result of improvements in the medical care of critically ill patients and increased awareness of thrombotic complications among medical providers. Current recommendations for the management of VTE in children are largely based on data from pediatric registries and observational studies, or extrapolated from adult data. The scarcity of high-quality evidence-based recommendations has resulted in marked variations in the management of pediatric VTE among providers. The purpose of this article is to summarize our institutional approach for the management of VTE in children based on available evidence, guidelines, and clinical practice considerations. Therapeutic strategies reviewed in this article include the use of conventional anticoagulants, parenteral targeted anticoagulants, new direct oral anticoagulants, thrombolysis, and mechanical approaches for the management of pediatric VTE.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

Does Anticoagulant Medication Alter Fracture-Healing? A Morphological and Biomechanical Evaluation of the Possible Effects of Rivaroxaban and Enoxaparin Using a Rat Closed Fracture Model

Low molecular weight heparin (LMWH) is routinely used to prevent thromboembolism in orthopaedic surgery, especially in the treatment of fractures or after joint-replacement. Impairment of fracture-healing due to increased bone-desorption, delayed remodelling and lower calcification caused by direct osteoclast stimulation is a well-known side effect of unfractioned heparin. However, the effect of LMWH is unclear and controversial. Recent studies strongly suggest impairment of bone-healing in-vitro and in animal models, characterized by a significant decrease in volume and quality of new-formed callus. Since October 2008, Rivaroxaban (Xarelto) is available for prophylactic use in elective knee- and hip-arthroplasty. Recently, some evidence has been found indicating an in vitro dose independent reduction of osteoblast function after Rivaroxaban treatment. In this study, the possible influence of Rivaroxaban and Enoxaparin on bone-healing in vivo was studied using a standardized, closed rodent fracture-model. 70 male Wistar-rats were randomized to Rivaroxaban, Enoxaparin or control groups. After pinning the right femur, a closed, transverse fracture was produced. 21 days later, the animals were sacrificed and both femora harvested. Analysis was done by biomechanical testing (three-point bending) and micro CT. Both investigated substances showed histomorphometric alterations of the newly formed callus assessed by micro CT analysis. In detail the bone (callus) volume was enhanced (sign. for Rivaroxaban) and the density reduced. The bone mineral content was enhanced accordingly (sign. for Rivaroxaban). Trabecular thickness was reduced (sign. for Rivaroxaban). Furthermore, both drugs showed significant enlarged bone (callus) surface and degree of anisotropy. In contrast, the biomechanical properties of the treated bones were equal to controls. To summarize, the morphological alterations of the fracture-callus did not result in functionally relevant deficits.

Enoxaparin and rivaroxaban have different effects on human mesenchymal stromal cells in the early stages of bone healing

Objectives

Venous thromboembolism (VTE) is a major potential complication following orthopaedic surgery. Subcutaneously administered enoxaparin has been used as the benchmark to reduce the incidence of VTE. However, concerns have been raised regarding the long-term administration of enoxaparin and its possible negative effects on bone healing and bone density with an increase of the risk of osteoporotic fractures. New oral anticoagulants such as rivaroxaban have recently been introduced, however, there is a lack of information regarding how these drugs affect bone metabolism and post-operative bone healing.

Methods

We measured the migration and proliferation capacity of mesenchymal stem cells (MSCs) under enoxaparin or rivaroxaban treatment for three consecutive weeks, and evaluated effects on MSC mRNA expression of markers for stress and osteogenic differentiation.

Results

We demonstrate that enoxaparin, but not rivaroxaban, increases the migration potential of MSCs and increases their cell count in line with elevated mRNA expression of C-X-C chemokine receptor type 4 (CXCR4), tumor necrosis factor alpha (TNFα), and alpha-B-crystallin (CryaB). However, a decrease in early osteogenic markers (insulin-like growth factors 1 and 2 (IGF1, IGF2), bone morphogenetic protein2 (BMP2)) indicated inhibitory effects on MSC differentiation into osteoblasts caused by enoxaparin, but not by rivaroxaban.

Conclusions

Our findings may explain the adverse effects of enoxaparin treatment on bone healing. Rivaroxaban has no significant impact on MSC metabolism or capacity for osteogenic differentiation in vitro.

Cite this article: Dr H. Pilge. Enoxaparin and rivaroxaban have different effects on human mesenchymal stromal cells in the early stages of bone healing. Bone Joint Res 2016;5:95–100. DOI: 10.1302/2046-3758.53.2000595.

Effects of thromboprophylaxis on mesenchymal stromal cells during osteogenic differentiation: an in-vitro study comparing enoxaparin with rivaroxaban

Background

Low-molecular-weight heparins (e.g. Enoxaparin) are widely used to prevent venous thromboembolism after orthopaedic surgery, but there are reports about serious side effects including reduction in bone density and strength. In recent years new oral antithrombotic drugs (e.g. direct Factor Xa-inhibitor, Rivaroxaban) have been used to prevent venous thromboembolism. However, there is lack of information on the effects of these new drugs on human mesenchymal stromal cells during osteogenic differentiation and, therefore, effects during postoperative bone healing.

Methods

We evaluated the effects of Rivaroxaban and Enoxaparin on the proliferation, mRNA and surface receptor expression as well as differentiation capacity of primary human mesenchymal stromal cells during their osteogenic differentiation.

Results

Enoxaparin, but not Rivaroxaban treatment significantly increased human mesenchymal stromal cell (hMSC) proliferation during the first week of osteogenic differentiation while suppressing osteogenic marker genes, surface receptor expression and calcification.

Conclusions

This is the first paper to demonstrate that Rivaroxaban had no significant influence on hMSC differentiation towards the osteogenic lineage, indicating a less affected bone healing process compared with Enoxaparin in vitro. Based on these findings Rivaroxaban seems to be superior to Enoxaparin in early stages of bone healing in vitro.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-0966-2) contains supplementary material, which is available to authorized users.

Anticoagulants in children and adolescents

Thrombotic complications are increasing at a steady and significant rate in children, resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the older multitargeted agents (heparin, low-molecular-weight heparin, and warfarin) and the newer targeted agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the multitargeted and targeted anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. The various agents differ in their pharmacokinetics, requirements for therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The targeted anticoagulants have properties that may make them more attractive for use in specific clinical situations. Prospective clinical trial data are presented supporting the current and future use of these agents in children.

Anticoagulants in children and adolescents

Thrombotic complications are increasing at a steady and significant rate in children, resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the older multitargeted agents (heparin, low-molecular-weight heparin, and warfarin) and the newer targeted agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the multitargeted and targeted anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. The various agents differ in their pharmacokinetics, requirements for therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The targeted anticoagulants have properties that may make them more attractive for use in specific clinical situations. Prospective clinical trial data are presented supporting the current and future use of these agents in children.

Comparison of the effects of heparin and the direct factor Xa inhibitor, rivaroxaban, on bone microstructure and metabolism in adult rats

AIM

Deep venous thrombosis is a significant complication following surgery, and is associated with high morbidity and mortality in adults. The direct factor Xa inhibitor, rivaroxaban, is used to prevent venous thromboembolism in patients suffering from trauma and joint arthroplasty. The present study compared the effects of rivaroxaban and heparin on bone microstructure and metabolism in adult rats.

MATERIALS AND METHODS

Twenty-four Wistar rats were divided into sham, rivaroxaban and heparin groups. Rivaroxaban (1.5 mg·kg(-1)·d(-1)) and heparin (2 IU·g(-1)·d(-1)) were administered for 4 weeks. To assess changes in bone metabolism, serum calcium and phosphorus levels, and bone formation and resorption markers were examined. Micro-CT analysis was used to examine the microstructure of both trabecular and cortical bone. Dual energy X-ray absorptiometry was employed to detect bone mineral density (BMD).

RESULTS

Serum phosphorus levels were significantly lower in both rivaroxaban (1.33 ± 0.07 mmol/L) and heparin (1.33 ± 0.21 mmol/L) rats than in sham rats (1.71 ± 0.14 mmol/L). Activity and levels of bone formation markers, bone-specific alkaline phosphatase (BAP) and type I procollagen N-terminal pro-peptide (PINP), were 32.4 and 38.2% lower in heparin-treated rats than in sham rats. Bone resorption markers, pyridinoline (PYD) and deoxypyridinoline (DPD), were 20.1 and 34.3% higher in heparin-treated rats than in sham rats, respectively. By contrast, rivaroxaban only resulted in a decrease PINP levels. Bone volume fraction (BV/TV) decreased by 23.5 and 20.5% from those in sham rats, while trabecular separation (Tb.Sp) increased by 28.2 and 16.3% in trabecular bone of heparin- and rivaroxaban-treated rats, [corrected] respectively. Moreover, the microstructure of cortical bone and BMD were negatively affected by heparin but not by rivaroxaban.

CONCLUSION

Rivaroxaban leads to fewer adverse effects on bone microstructure than heparin.

Effect of heparin on the biological properties and molecular signature of human mesenchymal stem cells

Chronic use of heparin as an anti-coagulant for the treatment of thrombosis or embolism invokes many adverse systemic events including thrombocytopenia, vascular reactions and osteoporosis. Here, we addressed whether adverse effects might also be directed to mesenchymal stem cells that reside in the bone marrow compartment. Harvested human bone marrow-derived mesenchymal stem cells (hMSCs) were exposed to varying doses of heparin and their responses profiled. At low doses (<200 ng/ml), serial passaging with heparin exerted a variable effect on hMSC proliferation and multipotentiality across multiple donors, while at higher doses (≥ 100 μg/ml), heparin supplementation inhibited cell growth and increased both senescence and cell size. Gene expression profiling using cDNA arrays and RNA-seq analysis revealed pleiotropic effects of low-dose heparin on signaling pathways essential to hMSC growth and differentiation (including the TGFβ/BMP superfamily, FGFs, and Wnts). Cells serially passaged in low-dose heparin possess a donor-dependent gene signature that reflects their altered phenotype. Our data indicate that heparin supplementation during the culturing of hMSCs can alter their biological properties, even at low doses. This warrants caution in the application of heparin as a culture supplement for the ex vivo expansion of hMSCs. It also highlights the need for careful evaluation of the bone marrow compartment in patients receiving chronic heparin treatment.

Management of endocrine disease: Secondary osteoporosis: pathophysiology and management

Osteoporosis is a skeletal disorder characterized by decreased mass and compromised bone strength predisposing to an increased risk of fractures. Although idiopathic osteoporosis is the most common form of osteoporosis, secondary factors may contribute to the bone loss and increased fracture risk in patients presenting with fragility fractures or osteoporosis. Several medical conditions and medications significantly increase the risk for bone loss and skeletal fragility. This review focuses on some of the common causes of osteoporosis, addressing the underlying mechanisms, diagnostic approach and treatment of low bone mass in the presence of these conditions.

Heparin affects human bone marrow stromal cell fate: Promoting osteogenic and reducing adipogenic differentiation and conversion

Heparins are broadly used for the prevention and treatment of thrombosis and embolism. Yet, osteoporosis is considered to be a severe side effect in up to one third of all patients on long-term treatment. However, the mechanisms underlying this clinical problem are only partially understood. To investigate if heparin affects differentiation of skeletal precursors, we examined the effects of heparin on the osteogenic and adipogenic lineage commitment and differentiation of primary human bone marrow stromal cells (hBMSCs). Due to the known inverse relationship between adipogenesis and osteogenesis and the capacity of pre-differentiated cells to convert into the respective other lineage, we also determined heparin effects on osteogenic conversion and adipogenic differentiation/conversion. Interestingly, heparin did not only significantly increase mRNA expression and enzyme activity of the osteogenic marker alkaline phosphatase (ALP), but it also promoted mineralization during osteogenic differentiation and conversion. Furthermore, the mRNA expression of the osteogenic marker bone morphogenic protein 4 (BMP4) was enhanced. In addition, heparin administration partly prevented adipogenic differentiation and conversion demonstrated by reduced lipid droplet formation along with a decreased expression of adipogenic markers. Moreover, luciferase reporter assays, inhibitor experiments and gene expression analyses revealed that heparin had putative permissive effects on osteogenic signaling via the BMP pathway and reduced the mRNA expression of the Wnt pathway inhibitors dickkopf 1 (DKK1) and sclerostin (SOST). Taken together, our data show a rather supportive than inhibitory effect of heparin on osteogenic hBMSC differentiation and conversion in vitro. Further studies will have to investigate the net effects of heparin administration on bone formation versus bone resorption in vivo to unravel the molecular mechanisms of heparin-associated osteoporosis and reconcile conflicting experimental data with clinical observations.

The effects of dabigatran etexilate on fracture healing in rats: An experimental study

BACKGROUND

Deep vein thrombosis leading to pulmonary embolism is one of the major complication after fracture. After a fracture occurs, the coagulation cascade activates thrombin, a protease that finally generates clotting. Dabigatran etexilate reduce clot formation by inhibiting thrombin. Dabigatran etexilate is a widely used drug for thromboprophylaxis. There is no study of the effects of dabigatran etexilate on fracture healing in the literature, so we aimed to evaluate the effects of dabigatran etexilate on fracture healing.

MATERIALS AND METHODS

Thirty-six female Sprague Dawley rats were divided into 6 groups, each consisting of 6 rats. In all rats, right tibias were used for the fracture model. An oral regimen of dabigatran etexilate suspension in 0.5% hydroxyethylcellulose was administered to the rats. Although the first and second groups received 10 mg/kg daily doses, the third and fourth groups received 50 mg/kg daily doses. The fifth and sixth groups were assigned as sham groups and only hydroxyethylcellulose solution was administered. The first, third and fifth groups were sacrificed on 14(th) days; whereas the second, fourth and sixth groups were sacrificed on 28(th) days. Results were evaluated radiologically and histologically.

RESULTS

Radiologically and histologically no statistically significant differences were observed on the 14(th) day between the first, third and fifth groups; and on the 28(th) days between the second, fourth and sixth groups.

CONCLUSION

Radiological and histological evaluations revealed that fracture healing was not affected by dabigatran etexilate. We think that dabigatran etexilate can be used for the prophylaxis of thromboembolism in patients with fractures, but further clinical studies are mandatory.

Postpartum osteoporosis and vertebral fractures in two patients treated with enoxaparin during pregnancy

Postpartum osteoporosis (PPO) is a rare disease associated with pregnancy and lactation period. Here, we report severe PPO and multiple vertebral compression fractures in two patients treated with enoxaparin--low-molecular-weight heparin (LMWH)--throughout their pregnancy. A 34-year-old woman who has delivered her second baby 3 months ago presented with severe low-back pain. She was treated with enoxaparin 40 mg/day for 8 months during her pregnancy. Dual-energy X-ray absorptiometry (DEXA) showed low T- and Z-scores in lumbar (L) vertebras. In magnetic resonance imaging (MRI), severe height losses in thoracic (T) 12, L1, and L2 vertebras were detected. She was diagnosed to have severe PPO and multiple vertebral compression fractures and was prescribed risedronate 35 mg/week, calcium, and vitamin D. The other patient was a 36-year-old woman diagnosed with PPO and vertebral fractures at the third week postpartum. She was also treated with enoxaparin 60 mg/day during her pregnancy. Severe osteoporosis in L vertebras and height losses indicative for compression fractures in T5-8, T11-12, and L2-5 vertebras were detected by DEXA and MRI, respectively. She was treated with calcitonin 200 U/day, calcium, and vitamin D. These findings suggest that vertebral compression fractures and PPO may be one of the causes of severe back pain in postpartum patients. Treatment with LMWH during pregnancy might be considered as a new risk factor for this rare condition.

Medication-induced osteoporosis: screening and treatment strategies

Drug-induced osteoporosis is a significant health problem and many physicians are unaware that many commonly prescribed medications contribute to significant bone loss and fractures. In addition to glucocorticoids, proton pump inhibitors, selective serotonin receptor inhibitors, thiazolidinediones, anticonvulsants, medroxyprogesterone acetate, aromatase inhibitors, androgen deprivation therapy, heparin, calcineurin inhibitors, and some chemotherapies have deleterious effects on bone health. Furthermore, many patients are treated with combinations of these medications, possibly compounding the harmful effects of these drugs. Increasing physician awareness of these side effects will allow for monitoring of bone health and therapeutic interventions to prevent or treat drug-induced osteoporosis.