Activity Of Heparin Research Articles

Network pharmacology- and molecular simulation-based exploration of therapeutic targets and mechanisms of heparin for the treatment of sepsis/COVID-19

Critically infected patients with COVID-19 (coronavirus disease 2019) are prone to develop sepsis-related coagulopathy as a result of a robust immune response. The mechanism underlying the relationship between sepsis and COVID-19 is largely unknown. LMWH (low molecular weight heparin) exhibits both anti-inflammatory and anti-coagulating properties that result in a better prognosis of severely ill patients with COVID-19 co-associated with sepsis-induced coagulopathy or with a higher D-dimer value. Heparin-associated molecular targets and their mechanism of action in sepsis/COVID-19 are not well understood. In this work, we characterize the pharmacological targets, biological functions and therapeutic actions of heparin in sepsis/COVID-19 from the perspective of network pharmacology. A total of 38 potential targets for heparin action against sepsis/COVID-19 and 8 core pharmacological targets were identified, including IL6, KNG1, CXCL8, ALB, VEGFA, F2, IL10 and TNF. Moreover, enrichment analysis showed that heparin could help in treating sepsis/COVID-19 through immunomodulation, inhibition of the inflammatory response, regulation of angiogenesis and antiviral activity. The pharmacological effects of heparin against these targets were further confirmed by molecular docking and simulation analysis, suggesting that heparin exerts effective binding capacity by targeting the essential residues in sepsis/COVID-19. Prospective clinical practice evaluations may consider the use of these key prognostic indicators for the treatment of sepsis/COVID-19. Communicated by Ramaswamy H. Sarma

Combined action of albumin and heparin regulates lipoprotein lipase oligomerization, stability, and ligand interactions

Combined action of albumin and heparin regulates lipoprotein lipase oligomerization, stability, and ligand interactions

Enoxaparin's potential mechanisms against SARS-CoV-2.

Since the coronavirus disease 2019 (COVID-19) pandemic emerged, the number of infected people has surged. As of late September 2022, about 614 million cases of COVID-19 have been confirmed and the death toll has exceeded 6.52 million1. Heparin and low-molecular-weight heparin (LMWH) are the anticoagulants of choice in the treatment of moderate to severe COVID-19, according to the most recent National Institutes of Health COVID-19 treatment guidelines2. Furthermore, heparin and LMWH have anti-inflammatory properties due to their ability to inhibit inflammatory cytokines, particularly interleukin-63. The antiviral activity of heparin against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is well documented in the literature, but this unique feature of enoxaparin is still unknown4. Recent evidence suggests that enoxaparin has potential mechanisms of action against SARS-CoV-2, giving the drug an important role in the treatment of COVID-19. Clausen et al.5 demonstrated that heparan sulphate (HS) plays a pivotal role in the pathogenesis of SARS-CoV-2, in which the SARS-CoV-2 spike protein can bind to both cellular HS and human angiotensin-converting enzyme 2 (ACE2) through its receptor-binding domain, and that it also augments the attachment of the SARS-CoV-2 spike protein and ACE2. One of the key antiviral mechanisms of enoxaparin comes from its ability to bind to the site of HS on the SARS-CoV-2 spike protein and ACE2, which inhibits the virus-cell entry and consequent infection6. The most recently proposed mechanism is that enoxaparin can significantly boost the alpha-1-antitrypsin inhibition of transmembrane serine protease 2, which cleaves the SARS-CoV-2 spike protein at the S1/S2 site for virus–cell entry7. This mechanism is clinically relevant and more likely to be resistant to the SARS-CoV-2 mutations. Furthermore, both enoxaparin and alpha-1-antitrypsin have anti-inflammatory properties in COVID-197. Finally, it has been revealed that heparanase plays an important role in the SARS-CoV-2 infection and has a significant relationship with the severity of COVID-19. Data suggest that LMWH may potentially inhibit heparanase and prevent SARS-CoV-2 cell entry and spread. Interestingly, heparanase has a detrimental effect on endothelial damage and causes vascular leakage and inflammation, which could be blocked by LMWH8. This document briefly reviews the suggested antiviral mechanisms of enoxaparin and can be used as the basis for further investigations. Ethical approval None. Source of funding None. Author contribution B.A.: conceptualization, writing—original draft. T.E.M.: writing—review and editing, supervision. Conflicts of interest disclosure The authors declare no conflicts of interest. Research registration unique identifying number (UIN) None. Guarantor All authors. Competing interests Sponsorships or competing interests that may be relevant to the content are disclosed at the end of this article. Data statement Our manuscript does not have new data to share. No funding was received for this correspondence item.

Heparin-Coated Dendronized Hyperbranched Polymers for Antimalarial Targeted Delivery.

The rampant evolution of resistance in Plasmodium to all existing antimalarial drugs calls for the development of improved therapeutic compounds and of adequate targeted delivery strategies for them. Loading antimalarials in nanocarriers specifically targeted to the parasite will contribute to the administration of lower overall doses, with reduced side effects for the patient, and of higher local amounts to parasitized cells for an increased lethality toward the pathogen. Here, we report the development of dendronized hyperbranched polymers (DHPs), with capacity for antimalarial loading, that are coated with heparin for their specific targeting to red blood cells parasitized by Plasmodium falciparum. The resulting DHP-heparin complexes exhibit the intrinsic antimalarial activity of heparin, with an IC50 of ca. 400 nM, added to its specific targeting to P. falciparum-infected (vs noninfected) erythrocytes. DHP-heparin nanocarriers represent a potentially interesting contribution to the limited family of structures described so far for the loading and targeted delivery of current and future antimalarial compounds.

Ultrasound-induced destruction of heparin-loaded microbubbles attenuates L-arginine-induced acute pancreatitis

PurposeAcute pancreatitis (AP) involves sudden inflammation caused by abnormal activation of pancreatic enzymes. The mechanisms underlying AP include oxidative stress, high levels of inflammatory mediators and inflammatory cell infiltration. Heparin, a key therapeutic drug, exerts anti-inflammatory, antioxidative, and anticoagulative effects. However, safe and effective drug delivery remains an obstacle. This study is the first to investigate the therapeutic effects of heparin-loaded microbubbles (HPMB) combined with ultrasound (UHPMB) and the role of heparin in acoustic cavitation. MethodsThe characteristics of the microbubbles, including particle size, concentration, release, stability, and development, were studied. Heparin concentration in the HPMB was measured, and heparin-induced anticoagulation was evaluated. Drug safety was explored using hemolysis and cell viability assessments. The ability of HPMB to alleviate oxidative stress and inflammation were investigated in vitro. L-arginine induces AP in vivo. UHPMB was used for AP treatment. Serum amylase levels were measured and pancreatic architecture and pathological features were evaluated to determine AP severity. In vivo efficacy was evaluated, and the underlying mechanism of heparin action during acoustic cavitation was explored. ResultsHPMB was spherical and presented as an emulsion-like solution without aggregation. HPMB was visible and stable and effectively released the drug under ultrasound (US). HPMB and UHPMB led to lower AP severity than in the untreated group. US-targeted microbubble destruction (UTMD) enhanced the therapeutic effect by decreasing oxidative stress and inflammation in AP models without injuring vital organs. UHPMB regulated VEGF/Flt-1 and SOD-1 expression. HPMB can also mitigate oxidative stress and inflammation in H2O2-pretreated cells. ConclusionUHPMB exhibits a strong ability not only to selectively target pancreatic lesions and release heparin but also to provide efficient protection by inhibiting oxidative stress and inflammation.

Anticoagulant Activity of Heparins from Different Animal Sources are Driven by a Synergistic Combination of Physical-chemical Factors.

Heparin has already been found in a variety of animal tissues but only few of them became effective sources for production of pharmaceutical preparations. Here, we correlate physical-chemical features and anticoagulant activities of structurally similar heparins employed in the past (from bovine lung, HBL), in the present (from porcine intestine, HPI) and in development for future use (from ovine intestine, HOI). Although they indeed have similar composition, our physical-chemical analyses with different chromatography and spectrometric techniques show that both HOI and HBL have molecular size notably lower than HPI and that the proportions of some of their minor saccharide components can vary substantially. Measurements of anticoagulant activities with anti-FIIa and anti-FXa assays confirmed that HPI and HOI have potency similar each other but significantly higher than HBL. Such a lower activity of HBL has been attributed to its reduced molecular size. Considering that HOI also has reduced molecular size, we find that its increased anticoagulant potency might result from an improved affinity to antithrombin (three times higher than HBL) promoted by the high content of N ,3,6-trisulfated glucosamine units, which in turn are directly involved in the heparin-antithrombin binding. Therefore, the anticoagulant activity of different heparins is driven by a balance between different physical-chemical components, especially molecular size and fine-tuning composition. Although such minor but relevant chemical differences reinforce the concept that heparins from different animal sources should indeed be considered as distinct drugs, HOI could be approved for interchangeable use with the gold standard HPI and as a suitable start material for producing new LMWHs.

The Role of Heparin in COVID-19: An Update after Two Years of Pandemics.

Coronavirus disease 2019 (COVID-19) is associated with an increased risk of venous thromboembolism (VTE) and coagulopathy, especially in critically ill patients. Endothelial damage induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a crucial pathogenetic mechanism for the development of complications in an acute phase of the illness and for several postdischarge sequalae. Heparin has been shown to have a positive impact on COVID-19 due to its anticoagulant function. Moreover, several other biological actions of heparin were postulated: a potential anti-inflammatory and antiviral effect through the main protease (Mpro) and heparansulfate (HS) binding and a protection from the damage of vascular endothelial cells. In this paper, we reviewed available evidence on heparin treatment in COVID-19 acute illness and chronic sequalae, focusing on the difference between prophylactic and therapeutic dosage.

Heparin activation of protein Z-dependent protease inhibitor (ZPI) allosterically blocks protein Z activation through an extended heparin-binding site

Protein Z (PZ)-dependent protease inhibitor (ZPI) is a plasma anticoagulant protein of the serpin superfamily, which is activated by its cofactor, PZ, to rapidly inhibit activated factor X (FXa) on a procoagulant membrane surface. ZPI is also activated by heparin to inhibit free FXa at a physiologically significant rate. Here, we show that heparin binding to ZPI antagonizes PZ binding to and activation of ZPI. Virtual docking of heparin to ZPI showed that a heparin-binding site near helix H close to the PZ-binding site as well as a previously mapped site in helix C was both favored. Alanine scanning mutagenesis of the helix H and helix C sites demonstrated that both sites were critical for heparin activation. The binding of heparin chains 72 to 5-saccharides in length to ZPI was similarly effective in antagonizing PZ binding and in inducing tryptophan fluorescence changes in ZPI. Heparin binding to variant ZPIs with either the helix C sites or the helix H sites mutated showed that heparin interaction with the higher affinity helix C site most distant from the PZ-binding site was sufficient to induce these tryptophan fluorescence changes. Together, these findings suggest that heparin binding to a site on ZPI extending from helix C to helix H promotes ZPI inhibition of FXa and allosterically antagonizes PZ binding to ZPI through long-range conformational changes. Heparin antagonism of PZ binding to ZPI may serve to spare limiting PZ and allow PZ and heparin cofactors to target FXa at different sites of action.

Development and In Vitro Whole Blood Hemocompatibility Screening of Endothelium-Mimetic Multifunctional Coatings.

Multifunctional antithrombotic surface modifications for blood-contacting medical devices have emerged as a solution for foreign surface-mediated coagulation disturbance. Herein, we have developed and evaluated an endothelium-inspired strategy to reduce the thrombogenicity of medical plastics by imparting nitric oxide (NO) elution and heparin immobilization on the material surface. This dual-action approach (NO+Hep) was applied to polyethylene terephthalate (PET) blood incubation vials and compared to isolated modifications. Vials were characterized to evaluate NO surface flux as well as heparin density and activity. Hemocompatibility was assessed in vitro using whole blood from human donors. Compared to unmodified surfaces, blood incubated in the NO+Hep vials exhibited reduced platelet aggregation (15% decrease AUC, p = 0.040) and prolonged plasma clotting times (aPTT = 147% increase, p < 0.0001, prothrombin time = 5% increase, p = 0.0002). Prolongation of thromboelastography reaction time and elevated antifactor Xa levels in blood from NO+Hep versus PET vials suggests some heparin leaching from the vial surface, confirmed by post-blood incubation heparin density assessment. Results suggest NO+Hep surface modification is a promising approach for blood-contacting plastics; however, careful tuning of NO flux and heparin stabilization are essential and require assessment using human blood as performed here.

Tuning the intentional corona of cerium oxide nanoparticles to promote angiogenesis via fibroblast growth factor 2 signalling.

Inadequate angiogenesis is a hallmark of conditions including cardiovascular diseases, stroke and chronic diabetic wounds, which exhibit tissue ischaemia ensuring that therapeutic strategies to promote angiogenesis are of great interest. However, many angiogenic treatments involve the delivery of growth factors which have limited clinical success due to poor stability, high manufacturing cost and poor efficacy. Cerium oxide nanoparticles (nanoceria) can either promote or inhibit angiogenesis depending on their surface corona chemistry. Here, nanoceria were functionalized with an intentional heparin corona, a polysaccharide which binds and signals growth factors, of different chain lengths and surface grafting density to establish their effect on angiogenesis. These nanoparticles promoted angiogenesis in vivo with the surface grafting density positively correlated with angiogenesis over the widest concentration range; however, chain length did not play a role. The heparin-nanoceria supported fibroblast growth factor 2 (FGF2) signalling in vitro and promoted FGF2-mediated angiogenesis in vivo. The nanoparticles were internalized by endothelial cells in vitro where they trafficked to the lysosomes and reduced cell viability suggesting that the angiogenic activity of heparin-nanoceria is mediated in the extracellular environment. Together, this study adds to our knowledge of the angiogenic effects of heparin-nanoceria towards finding new angiogenic treatments.

Heparinase Digestion of 3-O-Sulfated Sequences: Selective Heparinase II Digestion for Separation and Identification of Binding Sequences Present in ATIII Affinity Fractions of Bovine Intestinal Heparins

Binding to antithrombin-III (ATIII) determines the anticoagulant activity of heparin. The complexes formed between heparin and ATIII result from a specific pentasaccharide sequence containing a 3-O-sulfated glucosamine in medium position. Building block analysis of heparins, following heparinase digestion, is a critical method in quality control that provides a simple structural characterization of a complex product. Hence, in these applications, study of the digestion of 3-O-sulfated moieties merits special attention. With heparinase II, specific inhibition of cleavage of the non-reducing bond of 3-O-sulfated units is observed. This specificity was erroneously generalized to other heparinases when it was observed that in exhaustive digests of heparins with the heparinase mixture, resistant 3-O-sulfated tetrasaccharides were also obtained from the specific ATIII-binding pentasaccharides. In fact, the detection of unsaturated 3-O-sulfated disaccharides in digests of heparin by heparinases I+II+III, resulting from the cleavage of the 3-O sulfated unit by heparinase I in non-conventional sequences, shows that this inhibition has exceptions. Thus, in experiments where heparinase II is selectively applied, these sequences can only be digested into tetra- or hexasaccharides where the 3-O-sulfated glucosamine is shifted on the reducing end. Heparinase I+II+III and heparinase II digests with additional tagging by reductive amination with sulfanilic acid were used to study the structural neighborhood of 3-O-sulfated disaccharides in bovine mucosal heparin fractions with increasing affinity for ATIII. The 3-O-sulfated disaccharides detected in heparinase I+II+III digests turn into numerous specific 3-O-sulfated tetrasaccharides in heparinase II digests. Additionally, ATIII-binding pentasaccharides with an extra 3-O-sulfate at the reducing glucosamine are detected in fractions of highest affinity as heparinase II-resistant hexasaccharides with two consecutive 3-O-sulfated units.

Antithrombotic therapies for neurointerventional surgery: a 2021 French comprehensive national survey

BackgroundNeurointerventionists lack guidelines for the use of antithrombotic therapies in their clinical practice; consequently, there is likely to be significant heterogeneity in antithrombotic use between centers. Through a nationwide survey,...

Enoxaparin augments alpha-1-antitrypsin inhibition of TMPRSS2, a promising drug combination against COVID-19

The cell surface serine protease Transmembrane Protease 2 (TMPRSS2) is required to cleave the spike protein of SARS-CoV-2 for viral entry into cells. We determined whether negatively-charged heparin enhanced TMPRSS2 inhibition by alpha-1-antitrypsin (AAT). TMPRSS2 activity was determined in HEK293T cells overexpressing TMPRSS2. We quantified infection of primary human airway epithelial cells (hAEc) with human coronavirus 229E (HCoV-229E) by immunostaining for the nucleocapsid protein and by the plaque assay. Detailed molecular modeling was undertaken with the heparin–TMPRSS2–AAT ternary complex. Enoxaparin enhanced AAT inhibition of both TMPRSS2 activity and infection of hAEc with HCoV-229E. Underlying these findings, detailed molecular modeling revealed that: (i) the reactive center loop of AAT adopts an inhibitory-competent conformation compared with the crystal structure of TMPRSS2 bound to an exogenous (nafamostat) or endogenous (HAI-2) TMPRSS2 inhibitor and (ii) negatively-charged heparin bridges adjacent electropositive patches at the TMPRSS2–AAT interface, neutralizing otherwise repulsive forces. In conclusion, enoxaparin enhances AAT inhibition of both TMPRSS2 and coronavirus infection. Such host-directed therapy is less likely to be affected by SARS-CoV-2 mutations. Furthermore, given the known anti-inflammatory activities of both AAT and heparin, this form of treatment may target both the virus and the excessive inflammatory consequences of severe COVID-19.

Horizons of Heparin Therapy in COVID-19 and Pandemic-Related Diseases.

The disease caused by the coronavirus SARS-CoV-2, named COVID-19, has been spread around the world at a high transmission rate. It was initially considered to be an acute respiratory distress syndrome. Recent clinical data has highlighted that COVID-19 is characterized by a vascular dysfunction and thrombosis, which are not typical for many other acute respiratory diseases. Thrombotic complications are markers of severe COVID-19 and are associated with multiple organ failure and increased mortality. The application of unfractionated and/or low-molecular-weight heparins as anticoagulant medications, significantly reduced the severity of the disease and COVID-19-induced mortality, since heparin is a multifunctional agent. The goal of this review is to summarize the literature data on the pathogenic mechanisms of SARS-CoV-2 and to characterize the properties of heparin, which allow inhibiting these mechanisms at any stage of pathogenesis. We proposed a vicious circle hypothesis of SARS-CoV-2 pathogenesis, as well as an original approach to low-dose heparin therapy beyond its anticoagulant properties. The analysis of a wide range of effects and mechanisms of action of heparin will help create an idea of current possibilities and future potential of applying this drug.

The relationship between INTEM/HEPTEM coagulation time ratio and heparin plasma concentration in obstetric patients: an exploratory in vitro investigation.

Unfractionated heparin continues to be one of the main agents used for thromboprophylaxis in obstetrics, which can complicate the placement of neuraxial anesthetics. In this study, we explored the relationship between a point-of-care coagulation test (thromboelastometry) and plasma heparin concentrations in vitro. We obtained blood from consenting obstetric patients with uncomplicated pregnancies in their third trimester who were not in labour and had a specific hematocrit range. Blood was processed and analyzed. We added increasing amounts of unfractionated heparin to samples from 0 to 0.3 U·mL-1 in 0.05 U·mL-1 increments to simulate increasing doses of unfractionated heparin. We performed INTEM and HEPTEM testing in parallel with activated partial thromboplastin time (aPTT) testing. We created a model of the relationship between heparin concentration and the INTEM/HEPTEM coagulation time (IH CT) ratio using nonlinear regression. A similar model for aPTT was also created. Seventy-seven patients were included in the study. Only one concentration of heparin was added to blood samples of each patient. At a concentration of 0.05 U·mL-1, the IH CT ratio was less than or equal to 1.1 in 9/11 (82%) samples. Activated partial thromboplastin time was not prolonged (> 35 sec) until a concentration of 0.1 U·mL-1 heparin was added. In all samples, the IH CT ratio was prolonged at a concentration ≥ 0.2 U·mL-1 as measured by thromboelastometry; however, at no concentration of heparin was aPTT prolonged in all samples. The point-of-care IH CT ratio may be useful in identifying the presence of little to no heparin activity. Further research is needed to determine if this ratio can predict heparin activity in vivo.

Emicizumab does not interfere with the activated clotting time.

The activated clotting time (ACT) is a useful marker of unfractionated heparin (UFH) activity during cardiopulmonary bypass (CPB) or cardiac catheterization. Emicizumab, recently approved for bleeding prevention in haemophilia A patients, acts like FVIII but does not need prior activation; it therefore shortens coagulation times in assays using intrinsic pathway activators and so is expected to shorten the ACT. To evaluated emicizumab's impact on heparin-induced ACT (Hemochron®) prolongation. We measured the high-range (HR) ACT in citrated blood samples from healthy donors (HDs) (n=9), CPB patients (n=3) and emicizumab-treated patients (n=5) after spiking with UFH and/or emicizumab. The low range (LR) ACT was also measured in spiked-samples from HDs and emicizumab-treated patients. In HDs, the median [interquartile range] baseline HR-ACTs were similar with and without emicizumab (129 [123-138] and 136 [115-141]s for 50μg/ml, respectively); whatever the concentration of emicizumab (10 to 50μg/ml), increasing the UFH concentration (1-5 UI/ml) prolonged the HR-ACT. In blood from patients undergoing CPB, the HR-ACT prolongation observed during this procedure was not masked by emicizumab at any concentration. Likewise, the addition of increasing concentrations of UFH to blood from emicizumab-treated patients induced a concentration-dependent prolongation of HR-ACT. Baseline LR-ACT were prolonged in emicizumab-treated patients but as for HR-ACT, emicizumab does not prevent heparin-induced prolongation of LR-ACT. Emicizumab does not interfere with UFH-induced ACT prolongation. The hemochron® ACT can be used to monitor UFH in patients receiving emicizumab during CPB or cardiac catheterization.

Antithrombotic Activity of Heparinoid G2 and Its Derivatives from the Clam Coelomactra antiquata.

Clam heparinoid G2 (60.25 kDa) and its depolymerized derivatives DG1 (24.48 kDa) and DG2 (6.75 kDa) prepared from Coelomactra antiquata have been documented to have excellent fibrinolytic and anticoagulant activity. In this study, to further explore the antithrombotic activity of G2, DG1 and DG2, azure A, sheep plasma, and clot lytic rate assays were used to determine their anticoagulant and thrombolytic activity in vitro. The results indicated that the anticoagulant titer of G2 was approximately 70% that of heparin and the thrombolytic activity of DG2 was greater than G2, DG1, and heparin activities. Moreover, in a carrageenan-induced venous thrombosis model, oral administration of G2 and DG1 each at 20 mg/kg and 40 mg/kg for 7 days significantly reduced blacktail thrombus formation, increased tissue-type plasminogen activator, fibrin degradation products, and D-dimer levels, decreased von Willebrand factor and thromboxane B2 levels, and restored phylum and genus abundance changes of intestinal bacteria. DG2 had no antithrombotic effect. At 20 mg/kg, G2, DG1, and heparin had comparable antithrombotic activities, and DG1 at 40 mg/kg had more muscular antithrombotic activity than G2. Thus, DG1 could be an antithrombotic oral agent owing to its more robust antithrombotic activity and lower molecular weight.

The kinetics of heparin adsorption with Dowex 1x1 ion exchange resin

The recovery of heparin from the porcine intestinal mucosa by using the ion exchange resin was studied. The procedure involved the following steps: alkaline hydrolysis, ion exchange resin adsorption, and elution. The activity of heparin was measured by an antifactor Xa assay. The ammonium chloride/ammonium hydroxide was used as a buffer, and the effect of salt concentration on the adsorption efficiency was evaluated. The results showed that the highest heparin yield (86.17%) was achieved at the lowest concentration of ammonium chloride. The pseudo-first-order model was shown as more adequate to describe heparin adsorption onto the resin.

Improving outcome of COVID-19-associated thrombosis: the need for evaluation of fibrinolytic activation

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 and is known to have thrombotic complications. Various-sized thrombosis occurs in the arteries and veins, especially in lung tissue. The prevention and treatment of thrombosis is an important issue that is directly linked to its prognosis. Additionally, the drastic fibrinolytic enhancement and lethal bleeding in some severe COVID-19 are important issues. The efficacy of antiplatelet for COVID-19 is controversial. Thus, warfarin or tranexamic acid alone should be avoided. Heparin is effective for mild to moderate COVID-19 but is ineffective in severe cases since the anticoagulant activity of heparin is insufficient or heparin increases major bleeding. In severe COVID-19 cases with drastic fibrinolytic enhancement, heparin and nafamostat combination therapy may avoid lethal bleeding. In COVID-19 clinical practice, not only the coagulation activation was evaluated but also the fibrinolytic activation to consider treatment strategies.

Cationic Fluoropolyphosphazenes: Synthesis and Assembly with Heparin as a Pathway to Hemocompatible Nanocoatings

The development of state-of-the-art blood-contacting devices can be advanced through integrating hemocompatibility, durability, and anticoagulant functionalities within engineered nanoscale coatings. To enable all-aqueous assembly of nanocoatings combining omniphobic fluorinated features with the potent anticoagulant activity of hydrophilic heparin, two fluoropolymers containing cationic functionalities were synthesized─poly[(trifluoroethoxy)(dimethylaminopropyloxy)phosphazene], PFAP-O, and poly[(trifluoroethoxy)(dimethylaminopropylamino)phosphazene], PFAP-A. Despite a relatively high content of fluorinated pendant groups─approximately 50% (mol) in each─both polymers displayed solubility in aqueous solutions and were able to spontaneously form stable supramolecular complexes with heparin, as determined by dynamic light scattering and asymmetric flow field-flow fractionation methods. Heparin-containing coatings were then assembled by layer-by-layer deposition in aqueous solutions. Nanoassembled coatings were evaluated for potential thrombogenicity in three important categories of in vitro tests─coagulation by thrombin generation, platelet retention, and hemolysis. In all assays, heparin-containing fluoro-coatings consistently displayed superior performance compared to untreated titanium surfaces or fluoro-coatings assembled using poly(acrylic acid) in the absence of heparin. Short-term stability studies revealed the noneluting nature of these noncovalently assembled coatings.