FcRn augments induction of tissue factor activity by IgG-containing immune complexes.

Thromboembolism complicates disorders caused by immunoglobulin G (IgG)-containing immune complexes (ICs), but the underlying mechanisms are incompletely understood. Prior evidence indicates that induction of tissue factor (TF) on monocytes, a pivotal step in the initiation, localization, and propagation of coagulation by ICs, is mediated through Fcγ receptor IIa (FcγRIIa); however, the involvement of other receptors has not been investigated in detail. The neonatal Fc receptor (FcRn) that mediates IgG and albumin recycling also participates in cellular responses to IgG-containing ICs. Here we asked whether FcRn is also involved in the induction of TF-dependent factor Xa (FXa) activity by IgG-containing ICs by THP-1 monocytic cells and human monocytes. Induction of FXa activity by ICs containing IgG antibodies to platelet factor 4 (PF4) involved in heparin-induced thrombocytopenia (HIT), ß-2-glycoprotein-1 implicated in antiphospholipid syndrome, or red blood cells coated with anti-(α)-Rh(D) antibodies that mediate hemolysis in vivo was inhibited by a humanized monoclonal antibody (mAb) that blocks IgG binding to human FcRn. IgG-containing ICs that bind to FcγR and FcRn induced FXa activity, whereas IgG-containing ICs with an Fc engineered to be unable to engage FcRn did not. Infusion of an α-FcRn mAb prevented fibrin deposition after microvascular injury in a murine model of HIT in which human FcγRIIa was expressed as a transgene. These data implicate FcRn in TF-dependent FXa activity induced by soluble and cell-associated IgG-containing ICs. Antibodies to FcRn, now in clinical trials in warm autoimmune hemolytic anemia to lower IgG antibodies and IgG containing ICs may also reduce the risk of venous thromboembolism.

Functional, proteomic and phenotypic in vitro studies evidence podocyte injury after chronic exposure to heparin.

Unfractionated heparin (UFH) is a widely used anticoagulant that possess numerous properties including anti-inflammatory, anti-viral, anti-angiogenesis, and anti-metastatic effects. The effect of this drug was evaluated on the podocyte, an important actor of the glomerular filtration. Using a functional approach, we demonstrate that heparin treatment leads to a functional podocyte perturbation characterized by the increase of podocyte monolayer permeability. This effect is enhanced with time of exposure. Proteomic study reveals that heparin down regulate focal adhesion and cytoskeletal protein expressions as well as the synthesis of glomerular basement membrane components. This study clearly demonstrates that UFH may affect podocyte function by altering cytoskeleton organization, cell-cell contacts and cell attachment.

Safety and Functional Pharmacokinetic Profile of APAC, a Novel Intravascular Antiplatelet and Anticoagulant.

ABSTRACT: Vascular intervention-induced platelet and coagulation activation is often managed with a combination of antiplatelets and anticoagulants, with evident benefits, but with a risk of systemic bleeding. Antiplatelet and anticoagulant (APAC) is a dual antiplatelet and anticoagulant heparin bioconjugate, which targets vascular injury sites to act as a local antithrombotic. We assessed the nonclinical safety and exposure of intravenously infused APAC in rats and cynomolgus monkeys by using single-day and 14-day repeat dose toxicology and pharmacodynamic markers. Activated partial thromboplastin time (APTT) was used as a functional surrogate of anticoagulant exposure of APAC. Routine clinical in-life observations were followed by clinical pathology and necropsy. The no-observed-adverse-effect level (NOAEL) in rats for the single APAC dose was 20 mg/kg and for the repeated administration was 10 mg/kg/d. Monkeys tolerated a single APAC dose of 10 mg/kg, although the red blood cell count reduced 16%-19% correlating with tissue hemorrhage at vein puncture and affected muscle sites during handling of the animals. However, after 2-week recovery, all clinical signs were normal. The single dose NOAEL exceeded 3 mg/kg. The repeat administration of 3-6 mg/kg/d of APAC was tolerated, but some clinical signs were observed. The NOAEL for repeated dosing was 0.5 mg/kg/d. APAC prolonged APTT dose-dependently in both species, returning to baseline after 1.5 (<10 mg/kg) or essentially by 6 hours also under repetitive dosing. The toxicology profile supports the safety of an intravenous APAC dose of 0.5 mg/kg/d for possible clinical applications. APTT is an acceptable indicator of the immediate systemic anticoagulation effect of APAC.

Coronary Stents Decorated by Heparin/NONOate Nanoparticles for Anticoagulant and Endothelialized Effects.

In the treatment of coronary artery disease (CAD), the use of stent implantation often leads to clinical complications such as restenosis, delayed endothelial healing, and thrombosis. Here, we develop a double drug sustained-release coating for the stent surface by grafting heparin/NONOate nanoparticles (Hep/NONOates). The Hep/NONOates and surface modification of the stent were characterized by X-ray photoelectron spectroscopy, attenuated total reflection Fourier-transform infrared spectroscopy, static water contact angle, and scanning electron microscopy (SEM), and the release behaviors of the anticoagulant, heparin (Hep) and the bioactive molecule, nitric oxide (NO) were studied. Furthermore, the blood compatibility and cytotoxicity of the modified stent were evaluated by whole blood adhesion and platelet adhesion tests, hemolysis assay, morphological changes of red blood cells, plasma recalcification time assay, in vitro coagulation time tests, and MTT assay. Finally, the results of a rabbit carotid artery stent implantation experiment showed that the double drug sustained-release coating for the stent can accelerate regeneration of endothelial cells and keep good anticoagulant activity. This study can provide new design ideas based on nanotechnology for improving the safety and effectiveness of drug-eluting stents.

Pre-treatment with compound Danshen dripping pills prevents lipid infusion-induced microvascular dysfunction in mice.

CONTEXT: Recent studies have shown compound Danshen dripping pills (CDDP) could improve microcirculation in ischemic/reperfusion injury and other microvascular disorders. The mechanism for CDDP's role in microcirculation is not clear. OBJECTIVE: To explore the protective effects of CDDP on microvascular dysfunction. MATERIALS AND METHODS: C57BL/6 male mice (6-8 weeks) were randomized into control, model and CDDP groups (n = 10), which were treated with normal saline or CDDP (105.30 mg/kg), respectively. Then, lipid emulsion and heparin were infused via mice jugular vein to establish systemic microvascular dysfunction model. Coronary flow reserve (CFR) and leukocytes adhesion on microvascular wall were measured. Relative CD11b and CD62L expression levels on neutrophils were measured by flow cytometric analysis. Expression level of forkhead box transcription factor O1 (FOXO1) mRNA was identified by real-time PCR. RESULTS: Lipid infusion significantly attenuated the CFR (1.84 ± 0.14 vs. 2.65 ± 0.02) and increased the number of leukocytes adherent to microvascular wall in cremaster (4067.00 ± 581.20 cells/mm2 vs. 10.67 ± 4.81 cells/mm2). The expression level of CD11b and FOXO1 in neutrophils was also up-regulated by lipid infusion. Pre-treatment with CDDP significantly improved CFR (2.57 ± 0.29 vs. 1.84 ± 0.14), decreased the number of leukocytes adherent to microvascular wall (2500.00 ± 288.70 cells/mm2 vs. 4067.00 ± 581.20 cells/mm2) and down-regulated CD11b and FOXO1 expression. Discussion and conclusions: Pre-treatment with CDDP could prevent lipid infusion-induced systemic microvascular disorder including coronary and peripheral microvascular dysfunction. Down-regulated FOXO1 and decreased leukocyte adhesion might play an important role in the mechanisms of CDDP's efficacy.

Potential role of tracing stem cell transplantation and effects on the immune cell function of ferumoxytol combining with heparin and protamine in vivo/in vitro.

Cell labeling and tracing have played an increasingly important role in the field of stem cell transplantation. Nanocomplexes combining three Food and Drug Administration (FDA)-approved drugs: heparin (H), protamine (P), and ferumoxytol (F) (HPF nanocomplexes) display high labeling efficiency in human adipose tissue-derived stem cells (hADSCs), but their biological safety has not been determined. In this study, we tested the labeling efficiency of HPF in hADSCs through in vitro cytotoxicity studies and in vivo murine preclinical studies using HPF-labeled hADSCs. The labeling process did not cause cell apoptosis and had little effect on cell proliferation. In vivo magnetic resonance imaging (MRI) showed that the HPF-labeled cells produced a hypointense signal that did not affect liver and kidney functions. However, after injection of HPF-labeled cells into mice, lymphocyte transformation testing showed that T and B lymphocyte proliferation was significantly increased. These findings suggest that extensive safety testing of HPF nanocomplexes is necessary; the process to evaluate HPF as an investigative new drug application could therefore be postponed.

Preparation of highly efficient MRI contrast agents through complexation of cationic Gd(III)-containing metallosurfactant with biocompatible polyelectrolytes.

Novel contrast agents were developed through assembling of Gd(III) -containing metallosurfactant (MS) with biocompatible polyelectrolytes sodium hyaluronate (HA), heparinsodium (HS) and dextran sulfate sodium (DSS). The formed polyelectrolyte-surfactant complexes showed different structural patterns as the charge ratio increased, including spherical aggregates, rod-like aggregates and network patterns in monovalent HA system, while spherical structures emerged in multivalent HS and DSS systems. Energy dispersive spectroscopy analysis and scanning electron microscopy mapping showed the presence of Gd(III) in these complexes. Inductively coupled plasma atomic emission spectrometry was further used to quantify the contents of Gd(III) in the assemblies. T1 magnetic resonance imaging showed that these Gd(III) -loaded complexes exhibited relaxivity of up to 63.81 mM(-1) s(-1) , much higher than that of Ominiscan (4.64 mM(-1) s(-1) ). The cytotoxicity test in vitro demonstrated the excellent biocompatibility of these complexes, which is essential for clinical application.

Evaluation of antiproliferative and antimetastatic effects of heparin and erythropoietin on B16f10 melanoma cell line.

A number of chemotherapeutic agents and treatment strategies have been developed or designed to treat cancer patients. However, chemotherapeutic regimens frequently cause side-effects, one of which is anemia, a severe clinical problem for cancer patients. Erythropoietin is commonly used to treat anemia and reduce blood transfusions in cancer patients. Another agent which has potential use in cancer therapy is heparin, a glycosaminoglycan with a negative charge, known to increase the clearance of tumor cells from the blood in mice and also has anti-metastatic effects. In this current study, we investigated the effects of rEpo and heparin either as single agents or in combination on B16F10 melanoma cells. Contrary to our expectations based on the previous in vitro and in vivo studies, we have not found a significant growth-promoting effect of rEpo on B16F10 cells. We have also not observed a significant cytotoxic effect of heparin on B16F10 melanoma cell as assayed by MTT test (p > 0.05). However, heparin did significantly prevent the migration/proliferation of B16F10 cell in the wound assay as compared to the control cells after 24 h of incubation (p < 0.001). In addition, this effect of heparin was not prevented when rEpo was present in the medium in the wound assay (p < 0.01 as compared to the control). These results suggest that heparin may have a therapeutic potential as an anti-metastatic drug for cancer.

A Systematic Review and Meta-Analysis on the Therapeutic Efficacy of Heparin and Low Molecular Weight Heparins in Animal Studies of Traumatic Brain Injury.

The identification of effective pharmacotherapies for traumatic brain injury (TBI) remains a major challenge. Treatment with heparin and its derivatives is associated with neuroprotective effects after experimental TBI; however, the optimal dosage and method of administration, modes of action, and effects on hemorrhage remain unclear. Therefore, this review aimed to systematically evaluate, analyze, and summarize the available literature on the use of heparin and low molecular weight heparins (LMWHs) as treatment options for experimental TBI. We searched two online databases (PubMed and ISI Web of Science) to identify relevant studies. Data pertaining to TBI paradigm, animal subjects, drug administration, and all pathological and behavior outcomes were extracted. Eleven studies met our pre-specified inclusion criteria, and for outcomes with sufficient numbers, data from seven publications were analyzed in a weighted mean difference meta-analysis using a random-effects model. Study quality and risk of bias were also determined. Meta-analysis revealed that heparin and its derivatives decreased brain edema, leukocyte rolling, and vascular permeability, and improved neurological function. Further, treatment did not aggravate hemorrhage. These findings must be interpreted with caution, however, because they were determined from a limited number of studies with substantial heterogeneity. Also, overall study quality was low based on absences of data reporting, and potential publication bias was identified. Importantly, we found that there are insufficient data to evaluate the variables we had hoped to investigate. The beneficial effects of heparin and LMWHs, however, suggest that further pre-clinical studies are warranted.

Heparin-coated iron oxide nanoparticles: application as a liver contrast agent, toxicity and pharmacokinetics.

The prepared heparin-coated iron oxide nanoparticles (Hep-IONPs) contrasted cholangioma tumors in the liver in T2 MRI. The NPs were not toxic to rats and rabbits after 14 days of consecutive IV injections as observed from the monitoring of the body weight and biochemical and hematological parameters. No embryotoxic or immunotoxic side effects of the material were detected. However, we observed mutagenicity of iron oxide NPs in the Ames test and micronucleus assay. The pharmacokinetic studies showed that Hep-IONPs circulated in the blood for 14 days after IV injection. The liver iron level reached its maximum after 6 hours and slowly decreased within 30 days. Altogether, these results suggest that the synthesized Hep-IONPs are promising for use as the MRI contrast agent to identify liver malignancies.

A dose-response study in animals to evaluate the anticoagulant effect of the stage 2 unfractionated heparin USP monograph change.

The United States Pharmacopeia (USP) monograph for unfractionated heparin (UFH) was revised in October 2009. This revision was anticipated, based upon in vitro tests, to reduce UFH potency by approximately 10%. To study the potential in vivo consequences of the monograph change, we evaluated activated partial thromboplastin time (aPTT) and activated clotting time (ACT) responses in animals. Female mini-pigs and monkeys (n=8/species) were administered intravenously 60, 54, 48, or 42 U/kg and 50, 45, 40, or 35 U/kg "old" (pre-USP revision) UFH, respectively, in a Williams 4×4 crossover design. Blood samples for aPTT and ACT were collected at 15 min after dosing. The same study design was then repeated using "new" (post-USP revision) UFH. Mean "new" UFH aPTT and ACT values were generally lower than those for "old" UFH although individual animal responses varied considerably. The aPTT and ACT response was generally dose-proportional for both "old" and "new" UFH. These studies indicate that the USP monograph alteration for UFH may result in a modest reduction in the anticoagulant response across a population, but the variability in animal responses underscores the importance of individualization of clinical UFH dosing and the importance of anticoagulant test monitoring.

Enhanced Antimalarial Efficacy Obtained by Targeted Delivery of Artemisinin in Heparin-Coated Magnetic Hollow Mesoporous Nanoparticles.

Malaria is one of the deadliest infectious diseases threatening half of the world population. With the deterioration of the parasiticidal effect of the current antimalarials, novel approaches such as screening of more specific inhibitors and targeted delivery of drugs have been under intensive research. Herein, we prepare hollow mesoporous ferrite nanoparticles (HMFNs) of 200 nm with ferromagnetic properties using a one-pot hydrothermal reaction. A magnetically targeted drug-delivery system coloaded with artemisinin in the inner magnetite shell and heparin on the outer mesoporous shell (HMFN@ART@HEP) is developed. Specific targeting of the magnetic nanoparticles to the parasite-infected erythrocytes is achieved by the attraction between the HMFNs and hemozoin (paramagnetic), a vital metabolite of plasmodium in the erythrocytic stage. With the hemozoin production reaching the maximum during the schizont period of the parasite, HMFN@ART@HEPs are adsorbed to the infected red blood cells (iRBCs), which not only interferes with the release of merozoites but also significantly enhances the inhibitory efficacy due to the increased local concentration of artemisinin. Subsequently, the heparin coated on the surface of the nanoparticles can efficiently interfere with the invasion of freshly released merozoites to new RBCs through the specific interaction between the parasite-derived ligands and heparin, which further increases the inhibitory effect on malaria. As a cluster of heparin, heparin-coated nanoparticles provide stronger blocking capability than free heparin, resulting from multivalent interactions with surface receptors on merozoite. Thus, we have developed a HMFN-based delivery system with considerable antimalarial efficacy, which is a promising platform for treatment against malaria.

Mimicking the Endothelium: Dual Action Heparinized Nitric Oxide Releasing Surface.

The management of thrombosis and bacterial infection is critical to ensure the functionality of medical devices. While administration of anticoagulants is the current antithrombotic clinical practice, a variety of complications, such as uncontrolled hemorrhages or heparin-induced thrombocytopenia, can occur. Additionally, infection rates remain a costly and deadly complication associated with use of these medical devices. It has been hypothesized that if a synthetic surface could mimic the biochemical mechanisms of the endothelium of blood vessels, thrombosis could be reduced, anticoagulant use could be avoided, and infection could be prevented. Herein, the interfacial biochemical effects of the endothelium were mimicked by altering the surface of medical grade silicone rubber (SR). Surface modification was accomplished via heparin surface immobilization (Hep) and the inclusion of a nitric oxide (NO) donor into the SR polymeric matrix to achieve synergistic effects (Hep-NO-SR). An in vitro bacteria adhesion study revealed that Hep-NO-SR exhibited a 99.46 ± 0.17% reduction in viable bacteria adhesion compared to SR. An in vitro platelet study revealed Hep-NO-SR reduced platelet adhesion by 84.12 ± 6.19% compared to SR, while not generating a cytotoxic response against fibroblast cells. In a 4 h extracorporeal circuit model without systemic anticoagulation, all Hep-NO-SR samples were able to maintain baseline platelet count and device patency; whereas 66% of SR samples clotted within the first 2 h of study. Results indicate that Hep-NO-SR creates a more hemocompatible and antibacterial surface by mimicking two key biochemical functions of the native endothelium.

Prospective evaluation of heparin-induced thrombocytopenia expert probability and 4T scores in Chinese patients with suspected heparin-induced thrombocytopenia.

BACKGROUND: Diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. This study aimed to compare the diagnostic performance of HIT expert probability (HEP) and 4T scores, and to evaluate the inter-observer reliability for the 4T score in a clinical setting. METHODS: This prospective study included HIT-suspected patients between 2016 and 2018. Three hematologists assessed the HEP and 4T scores. Correlations between scores and anti-platelet factor 4 (anti-PF4)/heparin antibodies were evaluated. Receiver operating characteristic curves and area under the curve (AUC) were used to assess the predictive accuracy of these two scoring models. The intraclass correlation coefficient (ICC) was used to assess the inter-observer agreement of 4T scores between residents and hematologists. RESULTS: Of the 89 subjects included, 22 (24.7%) were positive for anti-PF4/heparin antibody. The correlations between antibody titer and either HEP or 4T scores were similar (r = 0.392, P < 0.01 for the HEP score; r = 0.444, P < 0.01 for the 4T score). No significant difference in the diagnostic performance was displayed between these two scores (AUC for the HEP score: 0.778 vs. AUC for the 4T score: 0.741, P = 0.357). Only 72 4T scores were collected from the residents, with a surprisingly low percentage of observers (43.1%) presenting the four individual item scores which made up their 4T score. The AUC of 4T score assessed by residents and hematologists was 0.657 (95% confidence interval [CI]: 536-0.765) and 0.780 (95% CI: 0.667-0.869, P < 0.05), respectively. The ICC of 4T score between residents and hematologists was 0.49 (95% CI: 0.29-0.65, P < 0.01), demonstrating a fair inter-observer agreement. CONCLUSIONS: The HEP score does not display a better performance for predicting HIT than the 4T score. With the unsatisfactory completion rate, the inter-observer agreement of 4T score in a tertiary hospital is fair, underscoring the necessity for continuing education for physicians.

A synthetic heparin mimetic that allosterically inhibits factor XIa and reduces thrombosis in vivo without enhanced risk of bleeding.

BACKGROUND: Human factor XIa (FXIa) is an actively pursued target for development of safer anticoagulants. Our long-standing hypothesis has been that allosterism originating from heparin-binding site(s) on coagulation enzymes is a promising approach to yield safer agents. OBJECTIVES: To develop a synthetic heparin mimetic as an inhibitor of FXIa so as to reduce clot formation in vivo but not carry high bleeding risk. METHODS: We employed a gamut of methods involving synthetic chemistry, biophysical biochemistry, enzyme assays, blood and plasma coagulation assays, and in vivo thrombosis models in this work. RESULTS: Sulfated chiro-inositol (SCI), a non-saccharide mimetic of heparin, was synthesized in three steps in overall yields of >50%. SCI inhibited FXIa with potency of 280 nmol/L and preferentially engaged FXIa's heparin-binding site to conformationally alter its active site. SCI inhibition of FXIa could be rapidly reversed by common antidotes, such as protamine. SCI preferentially prolonged plasma clotting initiated with recalcification, rather than thromboplastin, alluding to its intrinsic pathway-based mechanism. Human blood thromboelastography indicated good ex vivo anticoagulation properties of SCI. Rat tail bleeding and maximum-dose-tolerated studies indicated that no major bleeding or toxicity concerns for SCI suggesting a potentially safer anticoagulation outcome. FeCl3 -induced arterial and thromboplastin-induced venous thrombosis model studies in the rat showed reduced thrombus formation by SCI at 250 µg/animal, which matched enoxaparin at 2500 µg/animal. CONCLUSIONS: Overall, SCI is a highly promising, allosteric inhibitor of FXIa that induces potent anticoagulation in vivo. Further studies are necessary to assess SCI in animal models mimicking human clinical indications.

Comparison of the Effects of Contractubex Gel and Benzothiazole After Topical Application in an Experimental Model of Epidural Fibrosis in Rats.

BACKGROUND: Postoperative epidural adhesion is a frequent cause of failed back surgery syndrome, manifesting with back and leg pain or neurologic deficits. Development of preventive measures for epidural adhesion after laminectomy is critical to improve outcomes of lumbar surgery. We hypothesized that positive effects of topical application of Contractubex (CTX) gel and benzothiazole (BT) individually and in combination could aid in preventing epidural fibrosis in a rat laminectomy model. METHODS: Rats were randomly assigned to 2 control and 5 experimental groups (n = 8 for each group). The control(-) group received no surgery, whereas the control(+) group underwent laminectomy without any drug administration. In experimental groups, study agents applied to dura mater after laminectomy were 100mgCTX, 2.5%BT, 5%BT; 100mgCTXplus2.5%BT, and 100mgCTXplus5%BT. Laminectomy was performed at the L3 level for all rats. The extent of epidural fibrosis was assessed 4 weeks later macroscopically and histopathologically. Hepatic and renal toxicity of study drugs was assessed histopathologically. RESULTS: Topical CTX and BT individually and in combination reduced epidural fibrosis after laminectomy in rats. Although a meaningful decrease of epidural fibrosis with individual application of CTX and BT (2.5% or 5%) was obtained (P < 0.05), the effect of their combination was more pronounced without meaningful hepatic and renal toxicity (P < 0.05). CONCLUSIONS: Combined use of topical CTX and BT could be a potential therapy for epidural fibrosis. Further research with this agents for the prevention of epidural fibrosis is warranted.

Rapid immunoassays for diagnosis of heparin-induced thrombocytopenia: Comparison of diagnostic accuracy, reproducibility, and costs in clinical practice.

BACKGROUND: Immunoassays are crucial in the work-up of patients with suspected heparin-induced thrombocytopenia (HIT) and rapid tests have been recently developed. However, comparative data on diagnostic accuracy, reproducibility, and analytical costs of different immunoassays in clinical practice are limited. METHODS: Samples of 179 consecutive patients evaluated for suspected HIT in clinical practice using a polyspecific enzyme-linked immunoabsorbent assay (GTI diagnostics; ELISA) and a rapid particle gel immunoassay (PaGIA), were additionally analysed with a IgG-specific chemiluminescent immunoassay (AcuStar HIT-IgG). Presence of HIT was defined as a positive functional heparin-induced platelet aggregation test. Diagnostic accuracy was determined for low, intermediate and high thresholds as previously established (ELISA: optical density 0.4, 1.3, and 2.0 respectively; PaGIA: positive/negative, titre of 4, titre of 32; AcuStar HIT-IgG: 1.0 U/ml, 2.8, 9.4) and reproducibility was assessed by repeated measurements. Costs of test determination were calculated taking reagents, controls, and working time of technicians according to Swiss health care system into account. RESULTS: Data on PaGIA results were available for 171 patients (95.5%), ELISA for 144 patients (80.4%), and AcuStar HIT-IgG for 179 patients (100%). Sensitivity was above 95% for all assays at low and intermediate thresholds. Specificity increased with higher thresholds and was above 90% for all assays with intermediate and high thresholds. Specificity of AcuStar HIT-IgG (92.8%; 95% CI 87.7, 96.2) was significantly higher than PaGIA (83.0%; 95% CI 76.3, 88.5) and higher than ELISA (81.8%, 95% CI 74.2, 88.0) at low threshold (p<0.05). Reproducibility was adequate for all assays. Total costs per test were CHF 51.02 for ELISA, 117.70 for AcuStar HIT-IgG, and 83.13 for PaGIA. CONCLUSIONS: We observed favourable diagnostic accuracy measures and a high reproducibility for PaGIA and AcuStar HIT-IgG. Implementation into 24-hours-service might improve patient care but the results must be confirmed in other settings and larger populations as well.

In Vitro and In Vivo Biocompatibility Evaluation of Polyallylamine and Macromolecular Heparin Conjugates Modified Alginate Microbeads.

Host reactivity to biocompatible immunoisolation devices is a major challenge for cellular therapies, and a human screening model would be of great value. We designed new types of surface modified barium alginate microspheres, and evaluated their inflammatory properties using human whole blood, and the intraperitoneal response after three weeks in Wistar rats. Microspheres were modified using proprietary polyallylamine (PAV) and coupled with macromolecular heparin conjugates (Corline Heparin Conjugate, CHC). The PAV-CHC strategy resulted in uniform and stable coatings with increased anti-clot activity and low cytotoxicity. In human whole blood, PAV coating at high dose (100 µg/ml) induced elevated complement, leukocyte CD11b and inflammatory mediators, and in Wistar rats increased fibrotic overgrowth. Coating of high dose PAV with CHC significantly reduced these responses. Low dose PAV (10 µg/ml) ± CHC and unmodified alginate microbeads showed low responses. That the human whole blood inflammatory reactions paralleled the host response shows a link between inflammatory potential and initial fibrotic response. CHC possessed anti-inflammatory activity, but failed to improve overall biocompatibility. We conclude that the human whole blood assay is an efficient first-phase screening model for inflammation, and a guiding tool in development of new generation microspheres for cell encapsulation therapy.

Angiographic and clinical outcomes in patients receiving low-molecular-weight heparin versus unfractionated heparin in ST-elevation myocardial infarction treated with fibrinolytics in the CLARITY-TIMI 28 Trial.

BACKGROUND: Low-molecular-weight heparin (LMWH) offers pharmacological and practical advantages over unfractionated heparin (UFH). Whether these advantages translate into greater infarct-related artery patency and fewer adverse clinical events in patients with ST-elevation myocardial infarction (STEMI) receiving fibrinolytic therapy remains under study. METHODS AND RESULTS: We compared angiographic and clinical outcomes in patients treated with LMWH (n=1429) versus UFH (n=1431) in CLARITY-TIMI 28, a randomized trial of clopidogrel versus placebo in STEMI patients aged 18 to 75 years undergoing fibrinolysis. After comprehensive adjustment for baseline characteristics, therapeutic interventions, and a propensity score, treatment with LMWH was associated with a significantly lower rate of a closed infarct-related artery or death or myocardial infarction before angiography (13.5% versus 22.5%, adjusted OR 0.76, P=0.027). Treatment with LMWH was also associated with a significantly lower rate of cardiovascular death or recurrent myocardial infarction through 30 days (6.9% versus 11.5%, adjusted OR 0.68, P=0.030). The lower event rates were observed in patients allocated to clopidogrel and in those who underwent percutaneous coronary intervention. Rates of TIMI major bleeding through 30 days (1.6% versus 2.2%, P=0.27) and intracranial hemorrhage (0.6% versus 0.8%, P=0.37) were similar in the LMWH and UFH groups. Patients who received both clopidogrel and LMWH, in addition to a standard fibrinolytic and aspirin, had a particularly high rate of infarct-related artery patency (90.9%) and particularly low rates of cardiovascular death (3.2%), recurrent myocardial infarction (3.0%), and major bleeding (1.8%). CONCLUSIONS: In patients with STEMI receiving fibrinolytic therapy, use of LMWH with other standard therapies, including clopidogrel and aspirin, is associated with improved angiographic outcomes and lower rates of major adverse cardiovascular events.