Heparin: mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients

INTRODUCTION

Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients, effective monitoring assays and dose adjustment strategies are needed.

AREAS COVERED

This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients.

EXPERT OPINION

Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appear to favor using anti-Xa assay monitoring for heparin anticoagulation, which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Predicting Pharmacokinetics of Drugs Using Artificial Intelligence Tools: A Systematic Review

BACKGROUND AND OBJECTIVE

Pharmacokinetic studies encompass the examination of the absorption, distribution, metabolism, and excretion of bioactive compounds. The pharmacokinetics of drugs exert a substantial influence on their efficacy and safety. Consequently, the investigation of pharmacokinetics holds great importance. However, laboratory-based assessment necessitates the use of numerous animals, various materials, and significant time. To mitigate these challenges, alternative methods such as artificial intelligence have emerged as a promising approach. This systematic review aims to review existing studies, focusing on the application of artificial intelligence tools in predicting the pharmacokinetics of drugs.

METHODS

A pre-prepared search strategy based on related keywords was used to search different databases (PubMed, Scopus, Web of Science). The process involved combining articles, eliminating duplicates, and screening articles based on their titles, abstracts, and full text. Articles were selected based on inclusion and exclusion criteria. Then, the quality of the included articles was assessed using an appraisal tool.

RESULTS

Ultimately, 23 relevant articles were included in this study. The clearance parameter received the highest level of investigation, followed by the  area under the concentration-time curve (AUC) parameter, in pharmacokinetic studies. Among the various models employed in the articles, Random Forest and eXtreme Gradient Boosting (XGBoost) emerged as the most commonly utilized ones. Generalized Linear Models and Elastic Nets (GLMnet) and Random Forest models showed the most performance in predicting clearance.

CONCLUSION

Overall, artificial intelligence tools offer a robust, rapid, and precise means of predicting various pharmacokinetic parameters based on a dataset containing information of patients or drugs.

A practical guide to the management of immune thrombocytopenia co-existing with acute coronary syndrome

Introduction

Immune thrombocytopenia (ITP) management with co-existing acute coronary syndrome (ACS) remains challenging as it requires a clinically relevant balance between the risk and outcomes of thrombosis and the risk of bleeding. However, the literature evaluating the treatment approaches in this high-risk population is scarce.

Methods and Results

In this review, we aimed to summarize the available literature on the safety of ITP first- and second-line therapies to provide a practical guide on the management of ITP co-existing with ACS. We recommend holding antithrombotic therapy, including antiplatelet agents and anticoagulation, in severe thrombocytopenia with a platelet count < 30 × 109/L and using a single antiplatelet agent when the platelet count falls between 30 and 50 × 109/L. We provide a stepwise approach according to platelet count and response to initial therapy, starting with corticosteroids, with or without intravenous immunoglobulin (IVIG) with a dose limit of 35 g, followed by thrombopoietin receptor agonists (TPO-RAs) to a target platelet count of 200 × 109/L and then rituximab.

Conclusion

Our review may serve as a practical guide for clinicians in the management of ITP co-existing with ACS.

Anticoagulation in renal replacement therapies: Why heparin should be abandoned in critical ill patients?

Extracorporeal circuits used in renal replacement therapy (RRT) can develop thrombosis, leading to downtimes and reduced therapy efficiency. To prevent this, anticoagulation is used, but the optimal anticoagulant has not yet been identified. Heparin is the most widely used anticoagulant in RRT, but it has limitations, such as unpredictable pharmacokinetics, nonspecific binding to plasma proteins and cells, and the possibility of suboptimal anticoagulation or bleeding complications, specifically in critically ill patients with acute renal failure who are already at high risk of bleeding. Citrate anticoagulation is a better alternative, being considered a standard for continuous renal replacement therapy, since it is associated with a lower risk of bleeding complications and better efficacy, even in patients with acute renal failure or liver disease. The aim of this article is to provide an updated review of the different strategies of anticoagulation in renal replacement therapies that can be implemented in critical scenarios, focusing on the advantages and disadvantages of each one and the beneficial aspects of using citrate over heparin in critical ill patients.

Unresponsiveness of Activated Partial Thromboplastin Time to Bivalirudin in Adults Receiving Extracorporeal Membrane Oxygenation

Activated partial thromboplastin time (aPTT) is the standard for monitoring bivalirudin but demonstrates a nonlinear response at higher drug concentrations. The objective of this study was to assess the relationship between bivalirudin dose and aPTT in patients receiving extracorporeal membrane oxygenation (ECMO) to determine a threshold where aPTT unresponsiveness occurs. Two hundred fourteen adults receiving bivalirudin during ECMO between 2018 and 2022 were included. Piecewise regression in a linear mixed effects model was used to determine a bivalirudin dose threshold of 0.21 mg/kg/hr for aPTT unresponsiveness. For doses of less than 0.21 mg/kg/hr (n = 135), every 0.1 mg/kg/hr dose increase led to an aPTT increase of 11.53 (95% confidence interval [CI] = 9.85-13.20) seconds compared to only a 3.81 (95% CI = 1.55-6.06) seconds increase when dose was greater than or equal to 0.21 mg/kg/hr (n = 79) (pinteraction < 0.001). In multivariable logistic regression, venovenous configuration (odds ratio [OR] = 2.83, 95% CI = 1.38-5.77) and higher fibrinogen concentration (OR = 1.22, 95% CI = 1.05-1.42) were associated with greater odds of unresponsiveness, whereas older age (OR = 0.79, 95% CI = 0.63-0.98), kidney dysfunction (OR = 0.48, 95% CI = 0.25-0.92), and a higher baseline aPTT (OR = 0.89, 95% CI = 0.82-0.97) were associated with lower odds. Alternative methods are necessary to ascertain bivalirudin's hemostatic impact when doses exceed 0.21 mg/kg/hr during ECMO.

Effectiveness, Safety, and Costs of Thromboprophylaxis with Enoxaparin or Unfractionated Heparin Among Medical Inpatients With Chronic Obstructive Pulmonary Disease or Heart Failure

Background: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) are risk factors for venous thromboembolism (VTE). Enoxaparin and unfractionated heparin (UFH) help prevent hospital-associated VTE, but few studies have compared them in COPD or HF. Objectives: To compare effectiveness, safety, and costs of enoxaparin vs UFH thromboprophylaxis in medical inpatients with COPD or HF. Methods: This retrospective cohort study included adults with COPD or HF from the Premier PINC AI Healthcare Database. Included patients received prophylactic-dose enoxaparin or UFH during a >6-day index hospitalization (the first visit/admission that met selection criteria during the study period) between January 1, 2010, and September 30, 2016. Multivariable regression models assessed independent associations between exposures and outcomes. Hospital costs were adjusted to 2017 US dollars. Patients were followed 90 days postdischarge (readmission period). Results: In the COPD cohort, 114 174 (69%) patients received enoxaparin and 51 011 (31%) received UFH. Among patients with COPD, enoxaparin recipients had 21%, 37%, and 10% lower odds of VTE, major bleeding, and in-hospital mortality during index admission, and 17% and 50% lower odds of major bleeding and heparin-induced thrombocytopenia (HIT) during the readmission period, compared with UFH recipients (all P <.006). In the HF cohort, 58 488 (58%) patients received enoxaparin and 42 726 (42%) received UFH. Enoxaparin recipients had 24% and 10% lower odds of major bleeding and in-hospital mortality during index admission, and 13%, 11%, and 51% lower odds of VTE, major bleeding, and HIT during readmission (all P <.04) compared with UFH recipients. Enoxaparin recipients also had significantly lower total hospital costs during index admission (mean reduction per patient: COPD, 1280 ; H F , 2677) and readmission (COPD, 379 ; H F , 1024). Among inpatients with COPD or HF, thromboprophylaxis with enoxaparin vs UFH was associated with significantly lower odds of bleeding, mortality, and HIT, and with lower hospital costs. Conclusions: This study suggests that thromboprophylaxis with enoxaparin is associated with better outcomes and lower costs among medical inpatients with COPD or HF based on real-world evidence. Our findings underscore the importance of assessing clinical outcomes and side effects when evaluating cost-effectiveness.

Immune-stealth VP28-conjugated heparin nanoparticles for enhanced and reversible anticoagulation

Heparins are a family of sulfated linear negatively charged polysaccharides that have been widely used for their anticoagulant, antithrombotic, antitumor, anti-inflammatory, and antiviral properties. Additionally, it has been used for acute cerebral infarction relief as well as other pharmacological actions. However, heparin's self-aggregated macrocomplex may reduce blood circulation time and induce life-threatening thrombocytopenia (HIT) complicating the use of heparins. Nonetheless, the conjugation of heparin to immuno-stealth biomolecules may overcome these obstacles. An immunostealth recombinant viral capsid protein (VP28) was expressed and conjugated with heparin to form a novel nanoparticle (VP28-heparin). VP28-heparin was characterized and tested to determine its immunogenicity, anticoagulation properties, effects on total platelet count, and risk of inducing HIT in animal models. The synthesized VP28-heparin trimeric nanoparticle was non-immunogenic, possessed an average hydrodynamic size (8.81 ± 0.58 nm) optimal for the evasion renal filtration and reticuloendothelial system uptake (hence prolonging circulating half-life). Additionally, VP28-heparin did not induce mouse death or reduce blood platelet count when administered at a high dosein vivo(hence reducing HIT risks). The VP28-heparin nanoparticle also exhibited superior anticoagulation properties (2.2× higher prothrombin time) and comparable activated partial thromboplastin time, but longer anticoagulation period when compared to unfractionated heparin. The anticoagulative effects of the VP28-heparin can also be reversed using protamine sulfate. Thus, VP28-heparin may be an effective and safe heparin derivative for therapeutic use.

Hepatic artery thrombosis and use of anticoagulants and antiplatelet agents in pediatric liver transplantation

BACKGROUND

Hepatic artery thrombosis (HAT) is a reported complication of 5%-10% of pediatric liver transplantations, rates 3-4 times that seen in adults. Early HAT (seen within 14 days after transplant) can lead to severe allograft damage and possible urgent re-transplantation. In this report, we present our analysis of HAT in pediatric liver transplant from a national clinical database and examine the association of HAT with anticoagulant or antiplatelet medication administered in the post-operative period.

METHODS

Data were obtained from the Pediatric Health Information System database maintained by the Children's Hospital Association. For each liver transplant recipient identified in a 10-year period, diagnosis, demographic, and medication data were collected and analyzed.

RESULTS

Our findings showed an average rate of HAT of 6.3% across 31 centers. Anticoagulant and antiplatelet medication strategies varied distinctly among and even within centers, likely due to the fact there are no consensus guidelines. Notably, in centers with similar medication usage, HAT rates continue to vary. At the patient level, use of aspirin within the first 72 h of transplantation was associated with a decreased risk of HAT, consistent with other reports in the literature.

CONCLUSION

We suggest that concerted efforts to standardize anticoagulation approaches in pediatric liver transplant may be of benefit in the prevention of HAT. A prospective multi-institutional study of regimen-possibly including aspirin-following transplantation could have significant value.

Factors Influencing Unfractionated Heparin Pharmacokinetics and Pharmacodynamics During a Cardiopulmonary Bypass

BACKGROUND

Unfractionated heparin (UFH) is commonly used during cardiac surgery with a cardiopulmonary bypass to prevent blood clotting. However, empirical administration of UFH leads to variable responses. Pharmacokinetic and pharmacodynamic modeling can be used to optimize UFH dosing and perform real-time individualization. In previous studies, many factors that could influence UFH pharmacokinetics/pharmacodynamics had not been taken into account such as hemodilution or the type of UFH. Few covariates were identified probably owing to a lack of statistical power. This study aims to address these limitations through a meta-analysis of individual data from two studies.

METHODS

An individual patient data meta-analysis was conducted using data from two single-center prospective observational studies, where different UFH types were used for anticoagulation. A pharmacodynamic/pharmacodynamic model of UFH was developed using a non-linear mixed-effects approach. Time-varying covariates such as hemodilution and fluid infusions during a cardiopulmonary bypass were considered.

RESULTS

Activities of UFH's anti-activated factor/anti-thrombin were best described by a two-compartment model. Unfractionated heparin clearance was influenced by body weight and the specific UFH type. Volume of distribution was influenced by body weight and pre-operative fibrinogen levels. Pharmacodynamic data followed a log-linear model, accounting for the effect of hemodilution and the pre-operative fibrinogen level. Equations were derived from the model to personalize UFH dosing based on the targeted activated clotting time level and patient covariates.

CONCLUSIONS

The population model effectively characterized UFH's pharmacokinetics/pharmacodynamics in cardiopulmonary bypass patients. This meta-analysis incorporated new covariates related to UFH's pharmacokinetics/pharmacodynamics, enabling personalized dosing regimens. The proposed model holds potential for individualization using a Bayesian estimation.

Translational tissue-engineered vascular grafts: From bench to bedside

Cardiovascular disease is a primary cause of mortality worldwide, and patients often require bypass surgery that utilizes autologous vessels as conduits. However, the limited availability of suitable vessels and the risk of failure and complications have driven the need for alternative solutions. Tissue-engineered vascular grafts (TEVGs) offer a promising solution to these challenges. TEVGs are artificial vascular grafts made of biomaterials and/or vascular cells that can mimic the structure and function of natural blood vessels. The ideal TEVG should possess biocompatibility, biomechanical mechanical properties, and durability for long-term success in vivo. Achieving these characteristics requires a multi-disciplinary approach involving material science, engineering, biology, and clinical translation. Recent advancements in scaffold fabrication have led to the development of TEVGs with improved functional and biomechanical properties. Innovative techniques such as electrospinning, 3D bioprinting, and multi-part microfluidic channel systems have allowed the creation of intricate and customized tubular scaffolds. Nevertheless, multiple obstacles must be overcome to apply these innovations effectively in clinical practice, including the need for standardized preclinical models and cost-effective and scalable manufacturing methods. This review highlights the fundamental approaches required to successfully fabricate functional vascular grafts and the necessary translational methodologies to advance their use in clinical practice.

Effectiveness, safety, and costs of thromboprophylaxis with enoxaparin or unfractionated heparin in inpatients with obesity

Background

Obesity is a frequent and significant risk factor for venous thromboembolism (VTE) among hospitalized adults. Pharmacologic thromboprophylaxis can help prevent VTE, but real-world effectiveness, safety, and costs among inpatients with obesity are unknown.

Objective

This study aims to compare clinical and economic outcomes among adult medical inpatients with obesity who received thromboprophylaxis with enoxaparin or unfractionated heparin (UFH).

Methods

A retrospective cohort study was performed using the PINC AI™ Healthcare Database, which covers more than 850 hospitals in the United States. Patients included were ≥18 years old, had a primary or secondary discharge diagnosis of obesity [International Classification of Diseases (ICD)-9 diagnosis codes 278.01, 278.02, and 278.03; ICD-10 diagnosis codes E66.0x, E66.1, E66.2, E66.8, and E66.9], received ≥1 thromboprophylactic dose of enoxaparin (≤40 mg/day) or UFH (≤15,000 IU/day) during the index hospitalization, stayed ≥6 days in the hospital, and were discharged between 01 January 2010, and 30 September 2016. We excluded surgical patients, patients with pre-existing VTE, and those who received higher (treatment-level) doses or multiple types of anticoagulants. Multivariable regression models were constructed to compare enoxaparin with UFH based on the incidence of VTE, pulmonary embolism (PE)---------related mortality, overall in-hospital mortality, major bleeding, treatment costs, and total hospitalization costs during the index hospitalization and the 90 days after index discharge (readmission period).

Results

Among 67,193 inpatients who met the selection criteria, 44,367 (66%) and 22,826 (34%) received enoxaparin and UFH, respectively, during their index hospitalization. Demographic, visit-related, clinical, and hospital characteristics differed significantly between groups. Enoxaparin during index hospitalization was associated with 29%, 73%, 30%, and 39% decreases in the adjusted odds of VTE, PE-related mortality, in-hospital mortality, and major bleeding, respectively, compared with UFH (all p < 0.002). Compared with UFH, enoxaparin was associated with significantly lower total hospitalization costs during the index hospitalization and readmission periods.

Conclusions

Among adult inpatients with obesity, primary thromboprophylaxis with enoxaparin compared with UFH was associated with significantly lower risks of in-hospital VTE, major bleeding, PE-related mortality, overall in-hospital mortality, and hospitalization costs.

Antithrombin III infusion improves anticoagulation in congenital diaphragmatic hernia patients on extracorporeal membrane oxygenation

PURPOSE

Achieving effective anticoagulation during neonatal extracorporeal membrane oxygenation (ECMO) without increasing the risk of hemorrhage remains challenging. The use of antithrombin III (AT-III) for this purpose has been examined, but studies have been limited to intermittent bolus dosing. We aimed to evaluate the efficacy and safety of an institutionally developed AT-III continuous infusion protocol in neonates receiving ECMO for the treatment of congenital diaphragmatic hernia (CDH).

METHODS

In this single center, retrospective study, all neonates with a CDH who received ECMO support during the study period were included. Data on anticoagulation labs and therapy, life-threatening bleeding, and circuit changes were analyzed.

RESULTS

Eleven patients were divided into two groups: patients with AT-III continuous infusion (n = 5) and without (n = 6). There were no differences in the gestational age (p = 0.29), sex (p = 1.00), ECMO duration (p = 0.59), or initial AT-III levels (p = 0.76) between groups. Patients in the AT-III infusion group had on average 18.5% higher AT-III levels (p < 0.0001). Patients receiving continuous AT-III infusions spent a significantly higher percentage of ECMO time within the therapeutic range, measured using anti-Factor Xa levels (64.9±4.2% vs. 29.1±8.57%, p = 0.008), and required fewer changes to the heparin infusion rate (6.48±0.88 vs 2.38±0.36 changes/day changes/day, p = 0.005). Multivariate analysis revealed continuous infusion of AT-III did not increase the rate of intracranial or surgical bleeding (p = 0.27).

CONCLUSION

AT-III as a continuous infusion in CDH neonates on ECMO provides a decreased need to modify heparin infusion and more consistent therapeutic anticoagulation without increasing the risk of life-threatening bleeding.

Hyper-Branched Cyclodextrin-Based Polymers as Anticoagulant Agents: In Vitro and In Vivo Studies

This study tested the anticoagulant effect of cyclodextrin (CD) hyper-branched-based polymers (HBCD-Pols). These polymers were synthesized and tested for their coagulant characteristics in vitro and in vivo. Due to their polymeric structure and anionic nature, the polymers can chelate Ca²⁺, reducing the free quantity in blood. HBCD-Pol increased the blood clotting time, PT, and aPTT 3.5 times over the control, showing a better effect than even ethylenediaminetetraacetic acid (EDTA), as occured with recalcification time as well. A titration of HBCD-Pol and EDTA showed exciting differences in the ability to complex Ca²⁺ between both materials. Before executing in vivo studies, a hemocompatibility study was carried out with less than 5% red blood cell hemolysis. The fibrinogen consumption and bleeding time were analyzed in vivo. The fibrinogen was considerably decreased in the presence of HBCD-Pol in a higher grade than EDTA, while the bleeding time was longer with HBCD-Pols. The results demonstrate that the anticoagulant effect of this HBCD-Pol opens novel therapy possibilities due to the possible transport of drugs in this carrier. This would give combinatorial effects and a potential novel anticoagulant therapy with HBCD-Pol per se.

Anticoagulation Strategies during Extracorporeal Membrane Oxygenation: A Narrative Review

The development of extracorporeal life support technology has added a new dimension to the care of critically ill patients who fail conventional treatment options. Extracorporeal membrane oxygenation (ECMO)—specialized temporary life support for patients with severe cardiac or pulmonary failure—plays a role in bridging the time for organ recovery, transplant, or permanent assistance. The overall patient outcome is dependent on the underlying disease, comorbidities, patient reaction to critical illness, and potential adverse events during ECMO. Moreover, the contact of the blood with the large artificial surface of an extracorporeal system circuit triggers complex inflammatory and coagulation responses. These processes may further lead to endothelial injury and disrupted microcirculation with consequent end-organ dysfunction and the development of adverse events like thromboembolism. Therefore, systemic anticoagulation is considered crucial to alleviate the risk of thrombosis and failure of ECMO circuit components. The gold standard and most used anticoagulant during extracorporeal life support is unfractionated heparin, with all its benefits and disadvantages. However, therapeutic anticoagulation of a critically ill patient carries the risk of clinically relevant bleeding with the potential for permanent injury or death. Similarly, thrombotic events may occur. Therefore, different anticoagulation strategies are employed, while the monitoring and the balance of procoagulant and anticoagulatory factors is of immense importance. This narrative review summarizes the most recent considerations on anticoagulation during ECMO support, with a special focus on anticoagulation monitoring and future directions.

Marine Natural Products in Clinical Use

Marine natural products are potent and promising sources of drugs among other natural products of plant, animal, and microbial origin. To date, 20 drugs from marine sources are in clinical use. Most approved marine compounds are antineoplastic, but some are also used for chronic neuropathic pain, for heparin overdosage, as haptens and vaccine carriers, and for omega-3 fatty-acid supplementation in the diet. Marine drugs have diverse structural characteristics and mechanisms of action. A considerable increase in the number of marine drugs approved for clinical use has occurred in the past few decades, which may be attributed to increasing research on marine compounds in laboratories across the world. In the present manuscript, we comprehensively studied all marine drugs that have been successfully used in the clinic. Researchers and clinicians are hopeful to discover many more drugs, as a large number of marine natural compounds are being investigated in preclinical and clinical studies.

Investigations of the effectiveness of heparin variants as inhibitors of histones

BACKGROUND

Extracellular histones exert cytotoxic and procoagulant effects which contribute to immunothrombosis in vascular diseases such as sepsis. Heparin has been shown to neutralize the pathologic effects of histones in vitro and in animal models.

OBJECTIVES

To compare the effectiveness of unfractionated heparin (UFH), low-molecularweight heparin (LMWH), Vasoflux (lacks anticoagulant activity), and fondaparinux in neutralizing the cytotoxic and procoagulant activities of histones METHODS: Binding affinities between heparin variants and histone subunits were determined by Bio-layer Interferometry. The ability of heparin variants to diminish the cytotoxic and procoagulant effects of histones was studied by treating endothelial cells or monocytic THP-1 cells with histones ± heparin variants.

RESULTS

Unfractionated heparin, LMWH, and Vasoflux bind histone subunits with high affinities (Kd <1 pM-66.7 nM) whereas fondaparinux exhibited a low affinity (Kd of 3.06 µM-81.1 mM). UFH, LMWH, and Vasoflux neutralize histone-mediated cytotoxicity as well as monocytic procoagulant activity (as assessed by cell surface tissue factor and phosphatidylserine). In contrast, fondaparinux has no effect on these activities. All four heparin variants reverse histone-mediated impairment of APC generation in a dose-dependent manner.

CONCLUSIONS

The ability of heparin to neutralize the cytotoxic and procoagulant effects of histones require heparin fragments >1.7 kDa and is independent of the antithrombin-binding pentasaccharide. In contrast, the ability of heparin to neutralize histone-mediated impairment of APC generation is independent of size and anticoagulant activity. These findings suggest that heparin variants may have differential therapeutic potential in vascular diseases associated with elevated levels of histones.

Prophylaxis for Venous Thromboembolic Events in Elective Total Hip and Total Knee Arthroplasty

Venous thromboembolism (VTE) is a serious complication after major orthopaedic operations, such as a total hip (THA) and knee (TKA) arthroplasty. Therefore, perioperative VTE prophylaxis is recommended; a multitude of modern options are available, including both pharmacologic (aspirin, unfractionated and lowmolecular-weight heparin, vitamin K antagonists, and novel oral anticoagulants) and/or mechanical interventions (early mobilization, graduated compression stockings, intermittent pneumatic compression devices, and venous foot pumps). However, because of the abundance of these possibilities, it is crucial to understand the benefits and drawbacks of each VTE prophylaxis option to ensure that the optimal treatment plan is developed for each patient. The American College of Chest Physicians (AACP) and the American Academy of Orthopaedic Surgeons (AAOS) have both published individual guidelines on VTE prophylaxis regimens, alongside numerous studies evaluating the efficacy and outcomes of the different prophylaxis modalities. The purpose of this review is to provide a summary of the evidence on VTE prophylaxis after elective total hip and knee arthroplasty based on current guidelines and highlight the major concerns and potential complications.

Regional anaesthesia in patients on antithrombotic drugs: Joint ESAIC/ESRA guidelines

BACKGROUND

Bleeding is a potential complication after neuraxial and peripheral nerve blocks. The risk is increased in patients on antiplatelet and anticoagulant drugs. This joint guideline from the European Society of Anaesthesiology and Intensive Care and the European Society of Regional Anaesthesia aims to provide an evidence-based set of recommendations and suggestions on how to reduce the risk of antithrombotic drug-induced haematoma formation related to the practice of regional anaesthesia and analgesia.

DESIGN

A systematic literature search was performed, examining seven drug comparators and 10 types of clinical intervention with the outcome being peripheral and neuraxial haematoma. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the methodological quality of the included studies and for formulating recommendations. A Delphi process was used to prepare a clinical practice guideline.

RESULTS

Clinical studies were limited in number and quality and the certainty of evidence was assessed to be GRADE C throughout. Forty clinical practice statements were formulated. Using the Delphi-process, strong consensus (>90% agreement) was achieved in 57.5% of recommendations and consensus (75 to 90% agreement) in 42.5%.

DISCUSSION

Specific time intervals should be observed concerning the adminstration of antithrombotic drugs both prior to, and after, neuraxial procedures or those peripheral nerve blocks with higher bleeding risk (deep, noncompressible). These time intervals vary according to the type and dose of anticoagulant drugs, renal function and whether a traumatic puncture has occured. Drug measurements may be used to guide certain time intervals, whilst specific reversal for vitamin K antagonists and dabigatran may also influence these. Ultrasound guidance, drug combinations and bleeding risk scores do not modify the time intervals. In peripheral nerve blocks with low bleeding risk (superficial, compressible), these time intervals do not apply.

CONCLUSION

In patients taking antiplatelet or anticoagulant medications, practitioners must consider the bleeding risk both before and after nerve blockade and during insertion or removal of a catheter. Healthcare teams managing such patients must be aware of the risk and be competent in detecting and managing any possible haematomas.

An indicator displacement assay-based optical chemosensor for heparin with a dual-readout and a reversible molecular logic gate operation based on the pyranine/methyl viologen

We have reported an optical indicator displacement assay (IDA) for heparin with a UV-vis absorbance and fluorescence dual-readout based on pyranine/methyl viologen (MV²⁺). Upon introducing heparin, pyranine/MV²⁺ shows a clearly observable increase in UV-vis absorbance and a turn-on of the fluorescence signal. We have demonstrated that the ionic nature of buffers significantly affects the pyranine displacement and the zwitterionic HEPES was most suitable for heparin sensing. After careful screening of experimental conditions, the pyranine/MV²⁺-based optical chemosensor exhibits a fast, sensitive, and selective response toward heparin. It shows dynamic linear concentration of heparin in the ranges of 0.1-40 U·mL^-1 and 0.01-20 U·mL^-1 for the absorptive and fluorescent measurements, respectively, which both cover the clinically relevant levels of heparin. As with the animal experiments, the optical chemosensor has been demonstrated to be selective and effective for heparin level qualification in rat plasma. The chemosensor is readily accessible, cost-effective, and reliable, which holds a great promise for potential application on clinical and biological studies. Furthermore, this IDA system can serve as an IMPLICATION logic gate with a reversible and switchable logical manner.

Biocompatibility pathways and mechanisms for bioactive materials: The bioactivity zone

This essay analyzes the scientific evidence that forms the basis of bioactive materials, covering the fundamental understanding of bioactivity phenomena and correlation with the mechanisms of biocompatibility of biomaterials. This is a detailed assessment of performance in areas such as bone-induction, cell adhesion, immunomodulation, thrombogenicity and antimicrobial behavior. Bioactivity is the modulation of biological activity by characteristics of the interfacial region that incorporates the material surface and the immediate local host tissue. Although the term ‘bioactive material’ is widely used and has a well understood general meaning, it would be useful now to concentrate on this interfacial region, considered as ‘the bioactivity zone’. Bioactivity phenomena are either due to topographical/micromechanical characteristics, or to biologically active species that are presented in the bioactivity zone. Examples of topographical/micromechanical effects are the modulation of the osteoblast – osteoclast balance, nanotopographical regulation of cell adhesion, and bactericidal nanostructures. Regulation of bioactivity by biologically active species include their influence, especially of metal ions, on signaling pathways in bone formation, the role of cell adhesion molecules and bioactive peptides in cell attachment, macrophage polarization by immunoregulatory molecules and antimicrobial peptides. While much experimental data exists to demonstrate the potential of such phenomena, there are considerable barriers to their effective clinical translation. This essay shows that there is solid scientific evidence of the existence of bioactivity mechanisms that are associated with some types of biomaterials, especially when the material is modified in a manner designed to specifically induce that activity.

Acute Kidney Injury and Extracorporeal Membrane Oxygenation: Review on Multiple Organ Support Options

Extracorporeal membrane oxygenation (ECMO) is a temporary life support system used to assist patients with life-threatening severe cardiac and/or respiratory insufficiency. Patients requiring ECMO can be considered the sickest patients admitted to the intensive care unit (ICU). Acute kidney injury (AKI) represents a frequent complication during ECMO, affecting up to 70% of patients, with multifactorial pathophysiology and an independent risk factor for mortality. Severe AKI requiring Continuous Renal Replacement Therapy (CRRT) occurs in 20% of ECMO patients, but multiple indications and different timing may imply a significantly higher application rate in different centers. CRRT can be run in parallel to ECMO through different vascular access, or it can be conducted in series by connecting the circuits. Anticoagulation of ECMO is typically managed with systemic heparin, but several approaches can be applied for the CRRT circuit, from no anticoagulation to the addition of intra-filter heparin or regional citrate anticoagulation. The combination of CRRT and ECMO can be considered a form of multiple organ support therapy, but this approach still requires optimization in timing, set-up, anticoagulation, prescription and delivery. The aim of this report is to review the pathophysiology of AKI, the CRRT delivery, anticoagulation strategies and outcomes of patients with AKI treated with ECMO.

Pre-hospital heparin use for ST-elevation myocardial infarction is safe and improves angiographic outcomes

AIMS

This study aims to evaluate if pre-hospital heparin administration by paramedics is safe and improves clinical outcomes.

METHODS AND RESULTS

Using the multicentre Victorian Cardiac Outcomes Registry, linked with state-wide ambulance records, we identified consecutive patients undergoing primary percutaneous coronary intervention for STEMI between January 2014 and December 2018. Information on thrombolysis in myocardial infarction (TIMI) flow at angiography was available in a subset of cases. Patients receiving pre-hospital heparin were compared to those who did not receive heparin. Findings at coronary angiography and 30-day clinical outcomes were compared between groups. Propensity-score matching was performed for risk adjustment. We identified a total of 4720 patients. Of these, 1967 patients had TIMI flow data available. Propensity-score matching in the entire cohort yielded 1373 matched pairs. In the matched cohort, there was no observed difference in 30-day mortality (no-heparin 3.5% vs. heparin 3.0%, P = 0.25), MACCE (no-heparin 7% vs. heparin 6.2%, P = 0.44), and major bleeding (no-heparin 1.9% vs. heparin 1.4%, P = 0.64) between groups. Propensity-score analysis amongst those with TIMI data produced 552 matched pairs. The proportion of cases with TIMI 0 or 1 flow in the infarct-related artery (IRA) was lower among those receiving pre-hospital heparin (66% vs. 76%, P < 0.001) compared to those who did not.

CONCLUSION 

In this multicentre, propensity-score matched study, the use of pre-hospital heparin by paramedics was safe and is associated with fewer occluded IRAs in patients presenting with STEMI.

Thrombosis Prevention and Anticoagulation Management in the Pediatric Patient with Congenital Heart Disease

Thrombosis is one of the most frequent complications affecting children with congenital heart disease (CHD). Palliative and reparative cardiac surgeries are some of the main players contributing to the thrombosis risk in this patient population. Additional risk factors related to the CHD itself (e.g., cardiac dysfunction, arrhythmias, and polycythemia in cyanotic cardiac disorders) can contribute to thrombogenicity alone or combined with other factors. Thrombotic complications have been recognized as a significant cause of morbidity and mortality in this patient population. Here, we provide an overview of the pathophysiology and risk factors for thrombosis as well as the indications for and use of different anticoagulation, antiplatelet, and thrombolytic agents. In addition, we describe some of most common thrombotic complications and their management in the pediatric CHD population.

Anticoagulation in ECMO patients: an overview

Extracorporeal membrane oxygenation (ECMO) is a form of cardiorespiratory support, and is being increasingly used to support refractory heart and respiratory failure. It involves draining blood from the vascular system, which is then circulated outside the body by a mechanical pump and then later reinfused back into the circulation. The blood that is circulated outside the body comes in contact with a large surface area of non-endothelial biosurface. This exposure leads to a pro-thrombotic state, and hence anticoagulation is required. Unfractionated heparin is the most commonly used anticoagulation in most ECMO centers, but it does require close monitoring. Despite the advances made, hemostasis remains a challenge for physicians who manage patients on ECMO.

Unfractionated heparin using actual body weight without dose capping in obese pediatric patients-Subgroup analysis from an observational cohort study

To evaluate the correlation between an uncapped, actual body weight-based unfractionated heparin dosing strategy, we performed a body mass index-based subanalysis of a previously reported pediatric cohort. Nearly half (45%) of obese patients were supra-therapeutic on initial anti-FXa assessment. Obese patients achieved therapeutic anti-FXa significantly faster than nonobese patients (median 4 vs 12 hours, P = .0192) and were more likely to have any supra-therapeutic anti-FXa levels (77% vs 35%; P = .0021). There was no statistically significant difference in major or clinically relevant nonmajor bleeding rates between weight categories (P = .69). Prospective pediatric studies are warranted to confirm our findings.

Structural characterization of anticoagulant and antithrombotic polysaccharides isolated from Caesalpinia ferrea stem barks

This study aimed to isolate, characterize chemical-structurally and evaluate the effects of polysaccharides from Caesalpinia (Libidibia) ferrea stem barks in the haemostatic system. The deproteinated-polysaccharide extract (PE-Cf) after being fractionated by ion exchange chromatography-DEAE-cellulose resulted in three fractions (FI, FII, FIII) containing total carbohydrates (14.3-38%), including uronic acid (5-16%), and polyphenols (0.94-1.7 mg/g GAE). The polysaccharide fractions presented polydisperse profile in polyacrylamide gel electrophoresis (detected by Stains-All) and molecular masses (9.5 × 10⁴ Da-1.5 × 10⁵ Da) identified by gel permeation chromatography. FT-IR showed absorption bands (1630 cm^-1, 1396-1331 cm^-1), indicative of uronic acid, and a band at 1071 cm^-1, typical of COO^- groups of galacturonic acid. The NMR spectra of C. ferrea polysaccharides revealed a central core composed mainly by 5-linked α-Araf and minority components as α-Rhap and α-GalAp. UV spectra of fractions revealed discrete shoulders at 269-275 nm, characteristic of polyphenolic compounds. In vitro, polysaccharides inhibited the intrinsic and/or common coagulation pathway (aPTT test) (2.0-3.7 fold) and the platelet aggregation induced by 3 μM adenosine diphosphate (25-48%) and 5 μg/mL collagen (24%), but not that induced by arachidonic acid. In vivo, the polysaccharides inhibited (36-69%) venous thrombosis induced by hypercoagulability and stasis, showing discrete hemorrhagic effect. In conclusion, the polysaccharides of C. ferrea barks, containing arabinose, galactose, rhamnose and uronic acid, possess anticoagulant, antiplatelet and antithrombotic properties of low hemorrhagic risk, suggesting potential applicability in thromboembolic disorders.

The Utility of Diffusion-Weighted MRI Lesions to Compare the Effects of Different Heparinization Schemes in Intracranial Aneurysms Treated by Endovascular Intervention

Objective: Heparinization is applied to prevent ischemic complications in the endovascular treatment of intracranial aneurysms, but there is no unified heparinization scheme. Diffusion-weighted imaging (DWI) can be used to evaluate ischemia after endovascular therapy for intracranial aneurysms. The goal of this study is to apply DWI to evaluate the effects of different heparinization schemes on intracranial aneurysms treated with endovascular therapy.

Methods: We retrospectively reviewed 141 patients with 149 aneurysms treated with endovascular interventions from July 2019 to April 2020 at our center, including 96 aneurysms treated with local heparinization and 53 aneurysms treated with systemic heparinization. We collected the basic information of the patients, including age, sex, comorbidities, and aneurysm characteristics, and associated treatment data. New ischemic lesions detected by DWI were categorized belonging to four types. Multivariate logistic regression was used to compare the effects of different heparinization schemes on intracranial aneurysms treated with endovascular therapy.

Results: There were no significant differences in age, sex, hypertension, diabetes, and aneurysm size or location between the two groups. The incidence and distribution types of DWI abnormalities in the local heparinization groups and systemic heparinization groups were not significantly different (P > 0.05). There was a correlation between the laser engraving stent and postoperative DWI abnormalities (P < 0.003). Multivariate logistic regression analysis showed that the laser engraving stent was significantly correlated with postoperative DWI abnormalities (odds ratio, 4.71; 95% CI: 1.51–14.58; P = 0.007).

Conclusion: Compared with systemic heparinization, local heparinization does not increase the incidence of DWI abnormalities after endovascular treatment, and its application in this group of patients is safe and effective.

A conformally adapted all-in-one hydrogel coating: towards robust hemocompatibility and bactericidal activity

A conformally adapted all-in-one hydrogel coatings that exhibit both hemocompatibility and bactericidal activity possess the potential for applications in blood-contacting devices.

Design and Implementation of an Anti-Factor Xa Heparin Monitoring Protocol

BACKGROUND

The VA Northeast Ohio Healthcare System introduced a new nurse-driven anti-factor Xa (anti-Xa) protocol for monitoring unfractionated heparin to replace the previous activated partial thromboplastin time protocol.

OBJECTIVE

To design, implement, and evaluate the efficacy of the anti-Xa monitoring protocol.

METHODS

An interdisciplinary team of providers collaborated to develop and implement a nurse-driven, facility-wide anti-factor Xa protocol for monitoring unfractionated heparin therapy. The effectiveness of this protocol was evaluated by retrospective analysis.

RESULTS

We reviewed 100 medical records for compliance with the new anti-Xa monitoring protocol. We then evaluated 178 patients whose anticoagulation was monitored with the anti-Xa assay to determine the time to therapeutic range. We found that 80% of patients receiving the anti-Xa protocol achieved therapeutic anticoagulation within 24 hours, as compared with 54% of patients receiving the activated partial thromboplastin time protocol (P < .001). Protocol conversion also yielded a decrease in blood draws, dose adjustments, and potential calculation errors.

CONCLUSIONS

Monitoring intravenous heparin therapy with the anti-Xa assay rather than activated partial thromboplastin time resulted in a shorter time to therapeutic anticoagulation, longer maintenance of therapeutic levels, and fewer laboratory tests and heparin dosage changes. We believe the current practice of monitoring heparin treatment with activated partial thromboplastin time assays should be reexamined.

Unfractionated heparin infusion for treatment of venous thromboembolism based on actual body weight without dose capping

Controversy exists regarding the use of dose capping of weight-based unfractionated heparin (UFH) infusions in obese and morbidly obese patients. The primary objective of this study was to compare time to first therapeutic activated partial thromboplastin time (aPTT) in hospitalized patients receiving UFH for acute venous thromboembolism (VTE) among three body mass index (BMI) cohorts: non-obese (< 30 kg/m2), obese (30–39.9 kg/m2), and morbidly obese (⩾ 40 kg/m2). In this single-center, retrospective cohort study, patients were included if they ⩾ 18 years of age, had a documented VTE, and were on an infusion of UFH for at least 24 hours. Weight-based UFH doses were calculated using actual body weight. A total of 423 patients met the inclusion criteria, with 230 (54.4%), 146 (34.5%), and 47 (11.1%) patients in the non-obese, obese, and morbidly obese cohorts, respectively. Median times to therapeutic aPTT were 16.4, 16.6, and 17.1 hours in each cohort. Within 24 hours, the cumulative incidence rates for therapeutic aPTT were 70.7% for the non-obese group, 69.9% for the obese group, and 61.7% for the morbidly obese group (obese vs non-obese: HR = 1.02, 95% CI: 0.82–1.26, p = 0.88; morbidly obese vs non-obese: HR = 0.87, 95% CI: 0.62–1.21, p = 0.41). There was no significant difference in major bleeding events between BMI groups (obese vs non-obese, p = 0.91; morbidly obese vs non-obese, p = 0.98). Based on our study, heparin dosing based on actual body weight without a dose cap is safe and effective.

Direct-Acting Oral Anticoagulants and Their Reversal Agents-An Update

Background: Over the last ten years, a new class of drugs, known as the direct-acting oral anticoagulants (DOACs), have emerged at the forefront of anticoagulation therapy. Like the older generation anticoagulants, DOACs require specific reversal agents in cases of life-threatening bleeding or the need for high-risk surgery. Methods: Published literature was searched, and information extracted to provide an update on DOACS and their reversal agents. Results: The DOACs include the direct thrombin inhibitor—dabigatran, and the factor Xa inhibitors—rivaroxaban, apixaban, edoxaban, and betrixaban. These DOACs all have a rapid onset of action and each has a predictable therapeutic response requiring no monitoring, unlike the older anticoagulants, such as warfarin. Two reversal agents have been approved within the last five years: idarucizumab for the reversal of dabigatran, and andexanet alfa for the reversal of rivaroxaban and apixaban. Additionally, ciraparantag, a potential “universal” reversal agent, is currently under clinical development. Conclusions: A new generation of anticoagulants, the DOACs, and their reversal agents, are gaining prominence in clinical practice, having demonstrated superior efficacy and safety profiles. They are poised to replace traditional anticoagulants including warfarin.

Polyelectrolyte Complexes between Polycarboxylates and BMP-2 for Enhancing Osteogenic Differentiation: Effect of Chemical Structure of Polycarboxylates

Bone morphogenetic protein 2 (BMP-2) has received considerable attention because of its osteoinductivity, but its use is limited owing to its instability and adverse effects. To reduce the dose of BMP-2, complexation with heparin is a promising approach, because heparin enhances the osteoinductivity of BMP-2. However, the clinical use of heparin is restricted because of its anticoagulant activity. Herein, to explore alternative polymers that show heparin-like activity, four polycarboxylates, poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(aspartic acid) (PAsp), and poly(glutamic acid) (PGlu), were selected and their capability to modulate the osteoinductivity of BMP-2 was evaluated. Dynamic light scattering indicated that these polycarboxylates formed polyelectrolyte complexes with BMP-2. The osteogenic differentiation efficiency of MC3T3-E1 cells treated with the polycarboxylate/BMP-2 complexes was investigated in comparison to that of the heparin/BMP-2 complex. As a result, PGlu/BMP-2 complex showed the highest activity of alkaline phosphatase, which is an early-stage marker of osteogenic differentiation, and rapid mineralization. Based on these observations, PGlu could serve as an alternative to heparin in the regenerative therapy of bone using BMP-2.

The blood compatibility challenge. Part 1: Blood-contacting medical devices: The scope of the problem

Blood-contacting medical devices are an integral part of modern medicine. Such devices may be used for only a few hours or may be implanted for life. Despite advances in biomaterial science, clotting on medical devices remains a common problem. Systemic administration of antiplatelet drugs or anticoagulants is often needed to reduce the risk of clotting. Although effective, such therapy increases the risk of bleeding, which can be fatal. This chapter (a) describes some of the commonly used blood-contacting devices and their potential complications, (b) provides an overview of the mechanisms that drive device-associated clotting, and (c) reviews the strategies employed to attenuate clotting on blood-contacting medical devices. STATEMENT OF SIGNIFICANCE: This paper is part 1 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Pathogenic heparin-induced thrombocytopenia and thrombosis (HIT) antibodies determined by rapid functional flow cytometry

OBJECTIVES

Reliable diagnosis of heparin-induced thrombocytopenia and thrombosis (HIT) is mandatory for patient management, yet prompt determination of pathogenic antibodies remains an unmet clinical challenge. Common immunoassays carry inherent limitations and functional assays which detect antibody-mediated platelet activation are not usually readily available to routine laboratories, especially the serotonin release assay (SRA), being technically demanding, time consuming, and requires high level expertise. To overcome some of these limitations, we have developed a practical functional flow cytometric assay (FCA) for routine clinical use.

METHODS

A simple FCA is described which avoids platelet manipulation, is highly specific and sensitive compared with SRA, and provides rapid results.

RESULTS

Of the 650 consecutive samples, from HIT-suspected patients, 99 (15.3%) were positive by the PaGIA Heparin/PF4 immunoassay and 31 (4.8%) by FCA. Average platelet activation was 11-fold higher in PaGIA+/FCA+ vs PaGIA-/FCA- samples. Of 21 SRA-positive samples, 19 were FCA-positive (relative sensitivity 90.5%), and of 42 SRA-negative samples, 40 were FCA-negative (relative specificity 95.2%). The FCA showed significantly higher correlation with the clinical presentation of HIT (4Ts score) performed on 182 patients, compared with PaGIA Heparin/PF4 (ROC-plot analysis, AUC 0.93 vs 0.63, P < 0.001). At a 92% sensitivity, the assay specificity was 96%.

CONCLUSIONS

The present FCA is practical for routine testing, providing prompt reliable results for initial diagnosis and confirmation, to effectively assist in HIT patient management.

Heparin Differentially Impacts Gene Expression of Stromal Cells from Various Tissues

Pooled human platelet lysate (pHPL) is increasingly used as replacement of animal serum for manufacturing of stromal cell therapeutics. Porcine heparin is commonly applied to avoid clotting of pHPL-supplemented medium but the influence of heparin on cell behavior is still unclear. Aim of this study was to investigate cellular uptake of heparin by fluoresceinamine-labeling and its impact on expression of genes, proteins and function of human stromal cells derived from bone marrow (BM), umbilical cord (UC) and white adipose tissue (WAT). Cells were isolated and propagated using various pHPL-supplemented media with or without heparin. Flow cytometry and immunocytochemistry showed differential cellular internalization and lysosomal accumulation of heparin. Transcriptome profiling revealed regulation of distinct gene sets by heparin including signaling cascades involved in proliferation, cell adhesion, apoptosis, inflammation and angiogenesis, depending on stromal cell origin. The influence of heparin on the WNT, PDGF, NOTCH and TGFbeta signaling pathways was further analyzed by a bead-based western blot revealing most alterations in BM-derived stromal cells. Despite these observations heparin had no substantial effect on long-term proliferation and in vitro tri-lineage differentiation of stromal cells, indicating compatibility for clinically applied cell products.

Advances in monitoring anticoagulant therapy

Anticoagulant drugs directly or indirectly influence coagulation factors preventing fibrin formation, thus preventing blood clotting. They are classified into two groups according to the mode of application, namely parenteral and oral drugs. Among the latter, vitamin K antagonists (most often warfarin) were most widely used for almost a century. In recent years new oral anticoagulant drugs have become available that directly target either factor IIa or Xa (direct oral anticoagulants, DOACs). The proportion of patients to whom DOACs are prescribed is increasing because clinical studies have proved they are at least as effective and safe as vitamin K antagonists. Some of the anticoagulant drugs require regular laboratory monitoring, while others only need assessment of blood drug levels in specific clinical situations. This chapter provides an overview of appropriate laboratory tests used for either regular laboratory monitoring of therapy or occasional assessment of the anticoagulant effect of both parenteral and oral anticoagulant drugs used in clinical practice.

Sulfated non-anticoagulant heparin blocks Th2-induced asthma by modulating the IL-4/signal transducer and activator of transcription 6/Janus kinase 1 pathway

BACKGROUND

The efficacy of heparins and low-MW-heparins (LMWH) against human asthma has been known for decades. However, the clinical utility of these compounds has been hampered by their anticoagulant properties. Much effort has been put into harnessing the anti-inflammatory properties of LMWH but none have been used as therapy for asthma. Sulfated-non-anticoagulant heparin (S-NACH) is an ultra-LMWH with no systemic anticoagulant effects.

OBJECTIVE

The present study explored the potential of S-NACH in blocking allergic asthma and examined the potential mechanism by which it exerts its effects.

METHODS

Acute and chronic ovalbumin-based mouse models of asthma, splenocytes, and a lung epithelial cell line were used. Mice were challenged with aerosolized ovalbumin and administered S-NACH or saline 30 min after each ovalbumin challenge.

RESULTS

Sulfated-non-anticoagulant heparin administration in mice promoted a robust reduction in airway eosinophilia, mucus production, and airway hyperresponsiveness even after chronic repeated challenges with ovalbumin. Such effects were linked to suppression of Th2 cytokines IL-4/IL-5/IL-13/GM-CSF and ovalbumin-specific IgE without any effect on IFN-γ. S-NACH also reduced lung fibrosis in mice that were chronically-exposed to ovalbumin. These protective effects of S-NACH may be attributed to modulation of the IL-4/JAK1 signal transduction pathway through an inhibition of STAT6 phosphorylation and a subsequent inhibition of GATA-3 and inducible NO synthase expression. The effect of the drug on STAT6 phosphorylation coincided with a reduction in JAK1 phosphorylation upon IL-4 treatment. The protective effects of S-NACH treatment was associated with reduction of the basal expression of the two isoforms of arginase ARG1 and ARG2 in lung epithelial cells.

CONCLUSIONS

Our study demonstrates that S-NACH constitutes an opportunity to benefit from the well-known anti-asthma properties of heparins/LMWH while bypassing the risk of bleeding. Our results show, for the first time, that such anti-asthma effects may be associated with reduction of the IL-4/JAK1/STAT6 pathway.

Periprocedural antithrombotic management for lumbar puncture: Association of British Neurologists clinical guideline

Lumbar puncture (LP) is an important and frequently performed invasive procedure for the diagnosis and management of neurological conditions. There is little in the neurological literature on the topic of periprocedural management of antithrombotics in patients undergoing LP. Current practice is therefore largely extrapolated from guidelines produced by anaesthetic bodies on neuraxial anaesthesia, haematology groups advising on periprocedural management of antiplatelet agents and anticoagulants, and by neuroradiology on imaging-guided spinal procedures. This paper summarises the existing literature on the topic and offers recommendations to guide periprocedural antithrombotic management for LP, based on the consolidation of the best available evidence. ​

Tissue Engineering at the Blood-Contacting Surface: A Review of Challenges and Strategies in Vascular Graft Development

Tissue engineered vascular grafts (TEVGs) are beginning to achieve clinical success and hold promise as a source of grafting material when donor grafts are unsuitable or unavailable. Significant technological advances have generated small-diameter TEVGs that are mechanically stable and promote functional remodeling by regenerating host cells. However, developing a biocompatible blood-contacting surface remains a major challenge. The TEVG luminal surface must avoid negative inflammatory responses and thrombogenesis immediately upon implantation and promote endothelialization. The surface has therefore become a primary focus for research and development efforts. The current state of TEVGs is herein reviewed with an emphasis on the blood-contacting surface. General vascular physiology and developmental challenges and strategies are briefly described, followed by an overview of the materials currently employed in TEVGs. The use of biodegradable materials and stem cells requires careful control of graft composition, degradation behavior, and cell recruitment ability to ensure that a physiologically relevant vessel structure is ultimately achieved. The establishment of a stable monolayer of endothelial cells and the quiescence of smooth muscle cells are critical to the maintenance of patency. Several strategies to modify blood-contacting surfaces to resist thrombosis and control cellular recruitment are reviewed, including coatings of biomimetic peptides and heparin.

The mechanisms of sulfated polysaccharide drug of propylene glycol alginate sodium sulfate (PSS) on bleeding side effect

Propylene glycol alginate sodium sulfate (PSS), a sulfated polysaccharide derivative, has been used as a heparinoid drug to prevent and treat hyperlipidemia and ischemic cardio-cerebrovascular diseases in China for 30 years. But its bleeding risk should not be overlooked. Here we clarified the reasons and mechanism leading to bleeding side effect of PSS. It was found that PSS fractions with low mannuronic acid (M)/guluronic acid (G) ratio and high molecular weight (Mw) can excessively extend activated partial thromboplastin time (APTT) and thrombin time (TT), over-inhibit the thrombin (FIIa) activity mediated by anti-thrombin III (ATIII) to induce bleeding risk. In addition, the fraction of low M/G ratio can suppress platelet aggregation mediated by adenosine diphosphate (ADP) and induce platelet reduction by improving platelet antibody (PA)-IgA/G in serum and by inhibiting or damaging the bone marrow hematopoietic function. And the fraction of high Mw can restrain the reticulated platelet (RP) production, then reduce mean platelet volume (MPV) and platelet-large cell counts or ratio, and finally decrease platelet amount by inhibiting or damaging the bone marrow hematopoietic function. In brief, PSS fractions with low M/G ratio and high Mw were the main reasons to bring about bleeding by excessively suppressing coagulant factors activities and weakening platelet function. Our results suggested that it is very necessary to control the M/G ratio and the range of Mw of PSS to guarantee its safety and effectiveness in clinical.

Curcumin-lipoic acid conjugate as a promising anticancer agent on the surface of gold‑iron oxide nanocomposites: A pH-sensitive targeted drug delivery system for brain cancer theranostics

Brain tumor is a lethal, fast growing cancer and a difficult case for treatment. Receptor-mediated endocytosis has been recognized as one of the most effective methods for drug delivery to brain tissue by overcoming obstacles associated with conventional therapeutics. In this work, a targeted theranostic drug delivery system (DDS) was prepared based on gold‑iron oxide nanocomposites (Fe₃O₄@Au NCs). Lipoic acid-curcumin (LA-CUR) was synthesized and introduced as a novel anticancer drug, and glutathione (GSH) was exploited as the targeting ligand. Both LA-CUR and GSH were easily attached to Fe₃O₄@Au NCs via Au-S interaction. As a negatively charged nanocarrier, the prepared DDS showed relatively less protein adsorption. Accordingly, hemocompatibility assays (complement, platelet, and leucocyte activation) revealed its hemocompatible virtue, especially in respect of free LA-CUR. GSH functionalization led to 2-fold increase of cellular uptake in GSH receptor-positive astrocyte cells which could primarily indicate the probable ability of the DDS to bypass BBB. Cytotoxicity and apoptosis assays together showed the noticeably enhanced cytotoxicity of LA-CUR against cancerous U87MG cells (IC50=2.69μg/ml) in comparison with curcumin (IC50=21.31μg/ml); moreover, the DDS demonstrated relatively higher cytotoxicity against cancerous U87MG cells than normal astrocyte cells which was in accordance with pH sensitive mechanism of LA-CUR release. Besides, the results of in vitro magnetic resonance imaging (MRI) (relaxation rate (r₂)=80.73 (s^-1·mM^-1)) primarily revealed that the DDS can be applied as a negative MRI contrast agent. In sum, the prepared DDS appeared to be a promising candidate for brain cancer treatment and a favorable MRI contrast agent.