Blood Pressure Level and Variability During Long-Term Prasugrel or Clopidogrel Medication After Stroke: PRASTRO-I.

BACKGROUND AND PURPOSE: High blood pressure increases bleeding risk during treatment with antithrombotic medication. The association between blood pressure levels and the risk of recurrent stroke during long-term secondary stroke prevention with thienopyridines (particularly prasugrel) has not been well studied. METHODS: This was a post hoc analysis of the randomized, double-blind, multicenter PRASTRO-I trial (Comparison of Prasugrel and Clopidogrel in Japanese Patients With Ischemic Stroke-I). Patients with noncardioembolic stroke were randomly assigned (1:1) to receive prasugrel 3.75 mg/day or clopidogrel 75 mg/day for 96 to 104 weeks. Risks of any ischemic or hemorrhagic stroke, combined ischemic events, and combined bleeding events were determined based on the mean level and visit-to-visit variability, including successive variation, of systolic blood pressure (SBP) throughout the observational period. These risks were also compared between quartiles of mean SBP level and successive variation of SBP. RESULTS: A total of 3747 patients (age 62.1±8.5 years, 797 women), with a median average SBP level during the observational period of 132.5 mm Hg, were studied. All the risks of any stroke (146 events; hazard ratio, 1.318 [95% CI, 1.094-1.583] per 10-mm Hg increase), ischemic stroke (133 events, 1.219 [1.010-1.466]), hemorrhagic stroke (13 events, 3.247 [1.660-6.296]), ischemic events (142 events, 1.219 [1.020-1.466]), and bleeding events (47 events, 1.629 [1.172-2.261]) correlated with increasing mean SBP overall. Similarly, an increased risk of these events correlated with increasing successive variation of SBP (hazard ratio, 3.078 [95% CI, 2.220-4.225] per 10-mm Hg increase; 3.051 [2.179-4.262]; 3.276 [1.172-9.092]; 2.865 [2.042-4.011]; 2.764 [1.524-5.016], respectively). Event rates did not differ between the clopidogrel and prasugrel groups within each quartile of SBP or successive variation of SBP. CONCLUSIONS: Both high mean SBP level and high visit-to-visit variability in SBP were significantly associated with the risk of recurrent stroke during long-term medication with either prasugrel or clopidogrel after stroke. Control of hypertension would be important regardless of the type of antiplatelet drugs. Registration: URL: https://www.clinicaltrials.jp; Unique identifier: JapicCTI-111582.

Megakaryocytes and platelets from a novel human adipose tissue-derived mesenchymal stem cell line.

The clinical need for platelet transfusions is increasing; however, donor-dependent platelet transfusions are associated with practical problems, such as the limited supply and the risk of infection. Thus, we developed a manufacturing system for platelets from a donor-independent cell source: a human adipose-derived mesenchymal stromal/stem cell line (ASCL). The ASCL was obtained using an upside-down culture flask method and satisfied the minimal criteria for defining mesenchymal stem cells (MSCs) by The International Society for Cellular Therapy. The ASCL showed its proliferation capacity for ≥2 months without any abnormal karyotypes. The ASCL was cultured in megakaryocyte induction media. ASCL-derived megakaryocytes were obtained, with a peak at day 8 of culture, and ASCL-derived platelets (ASCL-PLTs) were obtained, with a peak at day 12 of culture. We observed that CD42b+ cells expressed an MSC marker (CD90) which is related to cell adhesion. Compared with peripheral platelets, ASCL-PLTs exhibit higher levels of PAC1 binding, P-selectin surface exposure, ristocetin-induced platelet aggregation, and ADP-induced platelet aggregation, as well as similar levels of fibrinogen binding and collagen-induced platelet aggregation. ASCL-PLTs have lower epinephrine-induced platelet aggregation. The pattern of in vivo kinetics after infusion into irradiated immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice was similar to that of platelet concentrates. ASCL-PLTs have similar characteristics to those of peripheral platelets and might have an additional function as MSCs. The establishment of the ASCL and its differentiation into ASCL-PLTs do not require gene transfer, and endogenous thrombopoietin is used for differentiation. The present protocol is a simple method that does not require feeder cells, further enhancing the clinical application of our approach.

Safety and Efficacy of Prasugrel in Elderly/Low Body Weight Japanese Patients with Ischemic Stroke: Randomized PRASTRO-II.

INTRODUCTION: The safety of prasugrel in elderly and/or low body weight Japanese patients with ischemic stroke who have a relatively high bleeding risk with antiplatelet therapy remains unknown. OBJECTIVE: We aimed to investigate the safety and efficacy of long-term prasugrel monotherapy for stroke prevention compared with clopidogrel in elderly and/or low body weight Japanese patients with non-cardioembolic ischemic stroke. METHODS: In this randomized, double-blind, comparative, phase III study, elderly (age ≥75 years) and/or low body weight (≤50 kg) Japanese patients with a previous history of non-cardioembolic ischemic stroke were assigned to a prasugrel 3.75 mg (PRA3.75) group, a prasugrel 2.5 mg (PRA2.5) group, or a clopidogrel 50 mg (CLO50) group and followed up for 48 weeks. The primary safety endpoint was the combined incidence of primary safety events, defined as life-threatening, major, and other clinically relevant bleeding. The efficacy endpoint was a composite of ischemic stroke, myocardial infarction, and death from other vascular causes. RESULTS: A total of 654 patients (age 76.4 ± 7.3 years, body weight 55.6 ± 9.3 kg, women 43.9%) from 74 medical institutions within Japan were enrolled. The combined incidence (95% CI) of primary safety events was 4.2% (1.9-7.8%), 1.9% (0.5-4.7%), and 3.6% (1.6-6.9%) in the PRA3.75 group (n = 216), PRA2.5 group (n = 215), and CLO50 group (n = 223), respectively (hazard ratios [HR] PRA3.75/CLO50, 1.13 [0.44-2.93]; PRA2.5/CLO50, 0.51 [0.15-1.69]). The incidences of bleeding leading to treatment discontinuation (95% CI) were 2.3% (0.8-5.3%), 0.9% (0.1-3.3%), and 2.2% (0.7-5.2%) in the PRA3.75, PRA2.5, and CLO50 groups, respectively (HRs PRA3.75/CLO50, 1.01 [0.29-3.48]; PRA2.5/CLO50, 0.41 [0.08-2.12]). There was no significant difference in all bleeding events between groups. The incidence of ischemic stroke, myocardial infarction, and death from other vascular causes was lower, but not significantly so, in patients treated with prasugrel than in patients treated with clopidogrel: PRA3.75, 0.0% (0/216); PRA2.5, 3.3% (7/215); and CLO50, 3.6% (8/223; HRs PRA3.75/CLO50, 0.00 [0.00-0.00]; PRA2.5/CLO50, 0.90 [0.32-2.47]). CONCLUSIONS: Elderly and/or low body weight -Japanese patients with previous non-cardioembolic ischemic stroke who received PRA3.75 showed similar results in terms of primary safety endpoint, and a numerically lower incidence of ischemic stroke, myocardial infarction, and death from other vascular causes, compared with those who received CLO50.

Pharmacodynamic assessment of prasugrel and clopidogrel in patients with non-cardioembolic stroke: a multicenter, randomized, active-control clinical trial.

Prasugrel, a novel P2Y12 receptor antagonist, has been shown to be more effective than clopidogrel for preventing cardiovascular events in patients with acute coronary syndromes undergoing percutaneous coronary intervention. We investigated the dose-response antiplatelet effects of prasugrel compared with clopidogrel in Japanese patients with non-cardioembolic stroke. The influence of cytochrome P450 (CYP) polymorphisms on the antiplatelet effects of both drugs was also compared. In this multicenter randomized active-control comparative study, patients were randomized to receive prasugrel 2.5 mg, 5 mg, or 7.5 mg (double blind) or clopidogrel 75 mg (open label) once daily for 14 days. The primary endpoint was inhibition of platelet aggregation (IPA) in response to adenosine diphosphate 20 µM within 8 h of study drug administration on day 14. Of the 66 patients randomized, data from 63 (prasugrel 2.5 mg, 5 mg, and 7.5 mg groups, n = 14, 16, and 18, respectively; clopidogrel group, n = 15) were used in the pharmacodynamic assessment. IPA (arithmetic mean ± SD) after prasugrel administration increased dose-dependently (33 ± 9%, 44 ± 11%, and 53 ± 14%, at 2.5 mg, 5 mg, and 7.5 mg, respectively) and was higher in these groups than after clopidogrel (23 ± 16%). In a subgroup of CYP2C19 intermediate metabolizers, IPA was higher in the prasugrel 5 mg and 7.5 mg groups than in the clopidogrel group. No death or serious adverse events were reported. Prasugrel was well tolerated at doses up to 7.5 mg/day and had antiplatelet effects higher than those of clopidogrel 75 mg/day. CYP2C19 polymorphisms may have reduced clopidogrel-induced IPA.

Major cardiovascular and bleeding events with long-term use of aspirin in patients with prior cardiovascular diseases: 1-year follow-up results from the Management of Aspirin-induced Gastrointestinal Complications (MAGIC) study.

Aspirin should be used for the prevention of cardiovascular (CV) events by the risk-benefit balance. This study was conducted to clarify CV and bleeding events in Japanese aspirin users with a history of CV diseases. This study was a prospective, nationwide, multicenter cooperative registry of Japanese patients with CV diseases at risk of thromboembolism who were taking aspirin (75-325 mg) for at least 1 year. We observed major CV and bleeding events during follow-up. Patients with history of ischemic stroke (IS), transient ischemic attack (TIA), coronary artery disease (CAD), atrial fibrillation (AF), and venous thromboembolism (VTE) were included and analyzed in this sutdy. CV events included IS, TIA, CAD, CV death, angioplasty or stenting, and hospitalization because of CV disease. Bleeding events included major bleeding requiring hospitalization and/or blood transfusion. A total of 1506 patients were categorized into IS/TIA (N = 540), CAD (N = 632), and AF/VTE (N = 232). Among them, 101 patients had two or more categories. CV and bleeding events occurred in 61 (3.82%/year) and 15 patients (0.93%/year), respectively. The annual rates of CV and bleeding events were 2.81% and 0.93% in IS/TIA, 5.32% and 0.75% in CAD, 1.15% and 1.15% in AF/VTE, and 6.44% and 0.91% in two or more disease categories, respectively. The Management of Aspirin-induced Gastrointestinal Complications (MAGIC) study clarified the rates of major CV and bleeding events with long-term use of aspirin in patients with prior CV diseases in real-world clinical practice. The risk-benefit balance of aspirin was acceptable in patients with IS/TIA, CAD, and multiple CV diseases but not in those with AF/VTE.Trial Registration: The MAGIC Study is registered at UMIN Clinical Trial Registry (www.umin.ac.jp/ctr/index-j.htm), number UMIN000000750.

Phospholipase Cß1 induces membrane tubulation and is involved in caveolae formation.

Lipid membrane curvature plays important roles in various physiological phenomena. Curvature-regulated dynamic membrane remodeling is achieved by the interaction between lipids and proteins. So far, several membrane sensing/sculpting proteins, such as Bin/amphiphysin/Rvs (BAR) proteins, are reported, but there remains the possibility of the existence of unidentified membrane-deforming proteins that have not been uncovered by sequence homology. To identify new lipid membrane deformation proteins, we applied liposome-based microscopic screening, using unbiased-darkfield microscopy. Using this method, we identified phospholipase Cß1 (PLCß1) as a new candidate. PLCß1 is well characterized as an enzyme catalyzing the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2). In addition to lipase activity, our results indicate that PLCß1 possessed the ability of membrane tubulation. Lipase domains and inositol phospholipids binding the pleckstrin homology (PH) domain of PLCß1 were not involved, but the C-terminal sequence was responsible for this tubulation activity. Computational modeling revealed that the C terminus displays the structural homology to the BAR domains, which is well known as a membrane sensing/sculpting domain. Overexpression of PLCß1 caused plasma membrane tubulation, whereas knockdown of the protein reduced the number of caveolae and induced the evagination of caveolin-rich membrane domains. Taken together, our results suggest a new function of PLCß1: plasma membrane remodeling, and in particular, caveolae formation.

Influence of cytochrome P450 polymorphisms on the antiplatelet effects of prasugrel in patients with non-cardioembolic stroke previously treated with clopidogrel.

This randomized double-blind crossover study aimed to investigate the influence of cytochrome P450 (CYP) 2C19 polymorphisms on the antiplatelet effects of prasugrel in patients with non-cardioembolic stroke treated with clopidogrel. Patients received clopidogrel 75 mg/day for > 4 weeks. Subsequently, patients received prasugrel 3.75 mg/day (group A; n = 64) or 2.5 mg/day (group B; n = 65) for 4 weeks followed by a 4 week switched-dose regimen. To assess the influence of CYP2C19 polymorphisms, patients were classified as extensive metabolizers (EMs), intermediate metabolizers (IMs), and poor metabolizers (PMs). The primary endpoint was P2Y12 reaction units (PRU) at the end of each 4 week treatment. A significant reduction in PRU was noted after treatment with prasugrel 3.75 mg/day compared with the pre-dose value (after treatment with clopidogrel) (p < 0.0001). By CYP2C19 phenotypes, a significant reduction in PRU was noted in IMs and PMs after treatment with prasugrel 3.75 mg/day and in PMs after treatment with prasugrel 2.5 mg/day, as compared with the pre-dose value (p < 0.0001). The plasma concentration of the active metabolite of clopidogrel was relatively low in PMs compared to EMs and IMs; prasugrel was similar across all CYP2C19 phenotypes. No major or clinically significant hemorrhagic adverse events occurred. By CYP2C19 phenotype, the antiplatelet effects of prasugrel were greater with 3.75 mg/day in IMs and PMs, and with 2.5 mg/day in PMs compared with clopidogrel 75 mg/day, without safety concerns. CYP2C19 polymorphisms did not affect the plasma concentration of the active metabolite of prasugrel or its antiplatelet effects. (JapicCTI-101044).

Aspirin for Stroke Prevention in Elderly Patients With Vascular Risk Factors: Japanese Primary Prevention Project.

BACKGROUND AND PURPOSE: The effect of aspirin in primary prevention of stroke is controversial among clinical trials conducted in Western countries, and no data are available for Asian populations with a high risk of intracranial hemorrhage. The objective of this study was to evaluate the effect of aspirin on the risk of stroke and intracranial hemorrhage in the Japanese Primary Prevention Project (JPPP). METHODS: A total of 14 464 patients (age, 60-85 years) with hypertension, dyslipidemia, and diabetes mellitus participated and were randomized into 2 treatment groups: 100 mg of aspirin or no aspirin. The median follow-up period was 5.02 years. RESULTS: The cumulative rate of fatal or nonfatal stroke was similar for the aspirin (2.068%; 95% confidence interval [CI], 1.750-2.443) and no aspirin (2.299%; 95% CI, 1.963-2.692) groups at 5 years; the estimated hazard ratio was 0.927 (95% CI, 0.741-1.160; P=0.509). Aspirin nonsignificantly reduced the risk of ischemic stroke or transient ischemic attack (hazard ratio, 0.783; 95% CI, 0.606-1.012; P=0.061) and nonsignificantly increased the risk of intracranial hemorrhage (hazard ratio, 1.463; 95% CI; 0.956-2.237; P=0.078). A Cox regression adjusted by the risk factors for all stroke, which were age >70 years, smoking, and diabetes mellitus, supported the above result. CONCLUSIONS: Aspirin did not show any net benefit for the primary prevention of stroke in elderly Japanese patients with risk factors for stroke, whereas age >70 years, smoking, and diabetes mellitus were risk factors for stroke regardless of aspirin treatment. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00225849.

Cardiovascular risk in relation to body mass index and use of evidence-based preventive medications in patients with or at risk of atherothrombosis.

AIM: Explore the relation between body mass index (BMI) and cardiovascular disease, and the influence of optimal medical therapy (OMT) on this relationship. METHODS AND RESULTS: Patients from the REACH cohort, an international, prospective cohort of patients with or at high risk of atherosclerosis with documentation of potential confounders, including treatments and risk factors, were followed up to 4 years (n = 54 285). Patients were categorized according to baseline BMI (ranging from underweight to Grade III obesity). Optimal medical therapy was defined as the use of the four cardioprotective medication classes (statins, ACE inhibitors/angiotensin II receptor blockers, ß-blockers, and antiplatelet agents). The main outcomes were all-cause mortality, cardiovascular (CV) mortality, and CV events. In primary and secondary prevention, a reverse J-shaped curve best described the relationship between BMI categories and the incidence of the various outcomes. In secondary prevention, the highest adjusted risks were observed for underweight patients (1.97, P < 0.01, and 1.29, P = 0.03, for CV mortality and CV events) and the lowest HRs were observed, respectively, in Grade II and Grade III obese patients (0.73, P < 0.01 and 0.80, P < 0.01). The proportion of patients on OMT increased with BMI from 10.1 to 36% (P < 0.001). The apparent CV protection conferred by obesity persisted in patients receiving OMT. CONCLUSION: An obesity paradox was observed in both primary and secondary CV prevention patients. The intensity of use of evidence-based preventive medications does not account for the paradoxical CV protection associated with obesity. At extremes of BMI, further interventions beyond OMT may be needed to reduce CV risk.

Induction of functional platelets from mouse and human fibroblasts by p45NF-E2/Maf.

Determinant factors leading from stem cells to megakaryocytes (MKs) and subsequently platelets have yet to be identified. We now report that a combination of nuclear factor erythroid-derived 2 p45 unit (p45NF-E2), Maf G, and Maf K can convert mouse fibroblast 3T3 cells and adult human dermal fibroblasts into MKs. To screen MK-inducing factors, gene expressions were compared between 3T3 cells that do not differentiate into MKs and 3T3-L1 cells known to differentiate into MKs. 3T3 cells transfected with candidate factors were cultured in a defined MK lineage induction medium. Among the tested factors, transfection with p45NF-E2/MafG/MafK lead to the highest frequency of CD41-positive cells. Adult human dermal fibroblasts transfected with these genes were cultured in MK lineage induction medium. Cultured cells had megakaryocytic features, including surface markers, ploidy, and morphology. More than 90% of MK-sized cells expressed CD41, designated induced MK (iMK). Infusion of these iMK cells into immunodeficient mice led to a time-dependent appearance of CD41-positive, platelet-sized particles. Blood samples from iMK-infused into thrombocytopenic immunodeficient mice were perfused on a collagen-coated chip, and human CD41-positive platelets were incorporated into thrombi on the chip, demonstrating their functionality. These findings demonstrate that a combination of p45NF-E2, Maf G, and Maf K is a key determinant of both megakaryopoiesis and thrombopoiesis.

Prasugrel, a third-generation P2Y12 receptor antagonist, in patients with coronary artery disease undergoing elective percutaneous coronary intervention.

BACKGROUND: Prasugrel is being developed in Japan as an antiplatelet therapy for use during percutaneous coronary intervention (PCI). Up to 70% of Japanese patients with coronary artery disease undergo elective PCI. The PRASugrel For Japanese PatIenTs with Coronary Artery Diseases Undergoing Elective PCI (PRASFIT-Elective) study investigated the efficacy and safety of different prasugrel dosing regimens in Japanese patients undergoing elective PCI. METHODS AND RESULTS: A total of 742 patients scheduled for elective coronary artery stenting were enrolled. Patients were randomized to receive either prasugrel (20/3.75 mg, loading/maintenance dose) or clopidogrel (300/75 mg) in a double-blind manner. Endpoints, including cardiovascular events and bleeding, were assessed at weeks 24-48. The incidence rate of major cardiovascular events (cardiovascular death, non-fatal myocardial infarction, or non-fatal ischemic stroke) up to week 24 was 4.1% (15/370) and 6.7% (25/372) in the prasugrel and clopidogrel groups, respectively. Other incidence rates were: non-coronary artery bypass graft-related major bleeding, 0% and 2.2%; major/minor bleeding, 1.6% and 3.0%; and all bleeding events, 38.1% and 34.4% in the prasugrel and clopidogrel groups, respectively. The incidence rate of bleeding-related adverse events was similar in both groups, being 40.8% and 35.8% in the prasugrel and clopidogrel groups, respectively. CONCLUSIONS: These results support the risk-benefit profile of an adjusted dosing regimen of prasugrel in Japanese patients undergoing PCI. Larger studies are required to confirm these findings.

PML targeting eradicates quiescent leukaemia-initiating cells.

The existence of a small population of 'cancer-initiating cells' responsible for tumour maintenance has been firmly demonstrated in leukaemia. This concept is currently being tested in solid tumours. Leukaemia-initiating cells, particularly those that are in a quiescent state, are thought to be resistant to chemotherapy and targeted therapies, resulting in disease relapse. Chronic myeloid leukaemia is a paradigmatic haematopoietic stem cell disease in which the leukaemia-initiating-cell pool is not eradicated by current therapy, leading to disease relapse on drug discontinuation. Here we define the critical role of the promyelocytic leukaemia protein (PML) tumour suppressor in haematopoietic stem cell maintenance, and present a new therapeutic approach for targeting quiescent leukaemia-initiating cells and possibly cancer-initiating cells by pharmacological inhibition of PML.

Low-dose aspirin for primary prevention of cardiovascular events in Japanese patients 60 years or older with atherosclerotic risk factors: a randomized clinical trial.

IMPORTANCE: Prevention of atherosclerotic cardiovascular diseases is an important public health priority in Japan due to an aging population. OBJECTIVE: To determine whether daily, low-dose aspirin reduces the incidence of cardiovascular events in older Japanese patients with multiple atherosclerotic risk factors. DESIGN, SETTING, AND PARTICIPANTS: The Japanese Primary Prevention Project (JPPP) was a multicenter, open-label, randomized, parallel-group trial. Patients (N = 14,464) were aged 60 to 85 years, presenting with hypertension, dyslipidemia, or diabetes mellitus recruited by primary care physicians at 1007 clinics in Japan between March 2005 and June 2007, and were followed up for up to 6.5 years, with last follow-up in May 2012. A multidisciplinary expert panel (blinded to treatment assignments) adjudicated study outcomes. INTERVENTIONS: Patients were randomized 1:1 to enteric-coated aspirin 100 mg/d or no aspirin in addition to ongoing medications. MAIN OUTCOMES AND MEASURES: Composite primary outcome was death from cardiovascular causes (myocardial infarction, stroke, and other cardiovascular causes), nonfatal stroke (ischemic or hemorrhagic, including undefined cerebrovascular events), and nonfatal myocardial infarction. Secondary outcomes included individual end points. RESULTS: The study was terminated early by the data monitoring committee after a median follow-up of 5.02 years (interquartile range, 4.55-5.33) based on likely futility. In both the aspirin and no aspirin groups, 56 fatal events occurred. Patients with an occurrence of nonfatal stroke totaled 114 in the aspirin group and 108 in the no aspirin group; of nonfatal myocardial infarction, 20 in the aspirin group and 38 in the no aspirin group; of undefined cerebrovascular events, 3 in the aspirin group and 5 in the no aspirin group. The 5-year cumulative primary outcome event rate was not significantly different between the groups (2.77% [95% CI, 2.40%-3.20%] for aspirin vs 2.96% [95% CI, 2.58%-3.40%] for no aspirin; hazard ratio [HR], 0.94 [95% CI, 0.77-1.15]; P = .54). Aspirin significantly reduced incidence of nonfatal myocardial infarction (0.30 [95% CI, 0.19-0.47] for aspirin vs 0.58 [95% CI, 0.42-0.81] for no aspirin; HR, 0.53 [95% CI, 0.31-0.91]; P = .02) and transient ischemic attack (0.26 [95% CI, 0.16-0.42] for aspirin vs 0.49 [95% CI, 0.35-0.69] for no aspirin; HR, 0.57 [95% CI, 0.32-0.99]; P = .04), and significantly increased the risk of extracranial hemorrhage requiring transfusion or hospitalization (0.86 [95% CI, 0.67-1.11] for aspirin vs 0.51 [95% CI, 0.37-0.72] for no aspirin; HR, 1.85 [95% CI, 1.22-2.81]; P = .004). CONCLUSIONS AND RELEVANCE: Once-daily, low-dose aspirin did not significantly reduce the risk of the composite outcome of cardiovascular death, nonfatal stroke, and nonfatal myocardial infarction among Japanese patients 60 years or older with atherosclerotic risk factors. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00225849.

Pharmacokinetic study of the structural components of adenosine diphosphate-encapsulated liposomes coated with fibrinogen γ-chain dodecapeptide as a synthetic platelet substitute.

Fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, ADP-encapsulated liposomes [H12-(ADP)-liposomes] were developed as a synthetic platelet alternative that specifically accumulates at bleeding sites as the result of interactions with activated platelets via glycoprotein IIb/IIIa and augments platelet aggregation by releasing ADP. The aim of this study is to characterize the pharmacokinetic properties of H12-(ADP)-liposomes and structural components in rats, and to predict the blood retention of H12-(ADP)-liposomes in humans. With use of H12-(ADP)-liposomes in which the encapsulated ADP and liposomal membrane cholesterol were radiolabeled with (14)C and (3)H, respectively, it was found that the time courses for the plasma concentration curves of (14)C and (3)H radioactivity showed that the H12-(ADP)-liposomes remained intact in the blood circulation for up to 24 hours after injection, and were mainly distributed to the liver and spleen. However, the (14)C and (3)H radioactivity of H12-(ADP)-liposomes disappeared from organs within 7 days after injection. The encapsulated ADP was metabolized to allantoin, which is the final metabolite of ADP in rodents, and was mainly eliminated in the urine, whereas the cholesterol was mainly eliminated in feces. In addition, the half-life of the H12-(ADP)-liposomes in humans was predicted to be approximately 96 hours from pharmacokinetic data obtained for mice, rats, and rabbits using an allometric equation. These results suggest that the H12-(ADP)-liposome has potential with proper pharmacokinetic and acceptable biodegradable properties as a synthetic platelet substitute.

Reactive oxygen species act through p38 MAPK to limit the lifespan of hematopoietic stem cells.

Hematopoietic stem cells (HSCs) undergo self-renewing cell divisions and maintain blood production for their lifetime. Appropriate control of HSC self-renewal is crucial for the maintenance of hematopoietic homeostasis. Here we show that activation of p38 MAPK in response to increasing levels of reactive oxygen species (ROS) limits the lifespan of HSCs in vivo. In Atm(-/-) mice, elevation of ROS levels induces HSC-specific phosphorylation of p38 MAPK accompanied by a defect in the maintenance of HSC quiescence. Inhibition of p38 MAPK rescued ROS-induced defects in HSC repopulating capacity and in the maintenance of HSC quiescence, indicating that the ROS-p38 MAPK pathway contributes to exhaustion of the stem cell population. Furthermore, prolonged treatment with an antioxidant or an inhibitor of p38 MAPK extended the lifespan of HSCs from wild-type mice in serial transplantation experiments. These data show that inactivation of p38 MAPK protects HSCs against loss of self-renewal capacity. Our characterization of molecular mechanisms that limit HSC lifespan may lead to beneficial therapies for human disease.

Statins and intracerebral hemorrhage: collaborative systematic review and meta-analysis.

BACKGROUND: A recent large, randomized trial suggested that statins may increase the risk of intracerebral hemorrhage. Accordingly, we systematically reviewed the association of statins with intracerebral hemorrhage in randomized and observational data. METHODS AND RESULTS: We screened 17 electronic bibliographic databases to identify eligible studies and consulted with experts in the field. We used DerSimonian-Laird random-effects models to compute summary risk ratios with 95% confidence intervals. Randomized trials, cohort studies, and case-control studies were analyzed separately. Only adjusted risk estimates were used for pooling observational data. We included published and unpublished data from 23 randomized trials and 19 observational studies. The complete data set comprised 248 391 patients and 14 784 intracerebral hemorrhages. Statins were not associated with an increased risk of intracerebral hemorrhage in randomized trials (risk ratio, 1.10; 95% confidence interval, 0.86-1.41), cohort studies (risk ratio, 0.94; 95% confidence interval, 0.81-1.10), or case-control studies (risk ratio, 0.60; 95% confidence interval, 0.41-0.88). Substantial statistical heterogeneity was evident for the case-control studies (I(2)=66%, P=0.01), but not for the cohort studies (I(2)=0%, P=0.48) or randomized trials (I(2)=30%, P=0.09). Sensitivity analyses by study design features, patient characteristics, or magnitude of cholesterol lowering did not materially alter the results. CONCLUSIONS: We found no evidence that statins were associated with intracerebral hemorrhage; if such a risk is present, its absolute magnitude is likely to be small and outweighed by the other cardiovascular benefits of these drugs.

Heparin-dependent and -independent anti-platelet factor 4 autoantibodies in patients with systemic lupus erythematosus.

OBJECTIVE: Antibodies that recognize complexes formed by platelet factor 4 (PF4) and heparin are involved in the pathogenesis of heparin-induced thrombocytopenia (HIT). This study was undertaken to investigate the prevalence and clinical correlations of anti-PF4 autoantibodies in patients with SLE. METHODS: We studied 118 patients with SLE, 78 with primary immune thrombocytopenia (ITP), 27 with primary APS, 2 with HIT (as positive controls) and 47 healthy controls. Heparin-dependent and -independent anti-PF4 antibodies were measured with an ELISA. Antibody binding was confirmed to be heparin-dependent when inhibited by the presence of a high concentration of heparin. Pathogenic anti-PF4 antibody was assessed by serotonin-release assay. RESULTS: Heparin-dependent anti-PF4 antibodies were detected in 11 SLE (9%) and 2 primary ITP (3%) patients, but at much lower levels than in HIT patients. In serotonin-release assays, only the HIT sera induced platelet activation in vitro. Heparin-independent anti-PF4 antibodies were detected in 17 SLE patients (14%). There was no correlation between the levels of heparin-dependent and -independent anti-PF4 antibodies. Cross-reactivity between these two antibodies was not detectable by ELISA competitive assay. Heparin-dependent anti-PF4 antibodies were associated with thrombocytopenia and IgM aCLs (P = 0.007 for both comparisons), while heparin-independent anti-PF4 antibody levels were correlated with SLE disease activity index (P = 0.0005). None of the SLE patients with anti-PF4 antibodies had previous heparin exposure. CONCLUSION: PF4 is an autoimmune target in SLE patients. Heparin-dependent and -independent anti-PF4 autoantibodies may be involved in different aspects of pathophysiology of SLE.

Effect of chronic kidney disease on platelet reactivity to dual-antiplatelet therapy in patients treated with drug-eluting stents.

We investigated the effect of chronic kidney disease (CKD) on platelet function in patients receiving dual-antiplatelet therapy after drug-eluting stent (DES) implantation. We examined 19 patients with CKD and 18 patients without CKD who underwent percutaneous coronary intervention (PCI) with DES. All of the patients had been on chronic aspirin treatment. Blood samples were obtained 20-24 h after a loading dose (300 mg) of clopidogrel. Platelet function was evaluated by measuring the closure time (CT) of a collagen/epinephrine (CEPI) or collagen/adenosine diphosphate (CADP) cartridge in the PFA-100 system. Maximum aggregation of agonist (epinephrine, ADP, collagen, or ristocetin)-induced platelet aggregation was also examined by light transmittance aggregometry. The frequency of the poor responders among CKD (n = 9, 47.4%) patients was significantly higher than that among non-CKD patients (n = 2, 11.1%, P = 0.016) as assessed using a CEPI-CT cartridge. Multiple logistic regression analysis revealed that CKD (odds ratio 7.39, 95% confidence interval 1.38-62.09, P = 0.0183] was the only independent determinant of the poor responders. There were no significant differences between the two groups in the value of CADP-CT or in maximum aggregation of epinephrine-, ADP-, collagen-, and ristocetin-induced platelet aggregation. Compared with non-CKD patients, CKD patients had lower response to aspirin therapy as assessed by the PFA-100 system with a CEPI cartridge. On the other hand, the platelet response to dual-antiplatelet therapy was not different between CKD and non-CKD patients.

Structural requirements for activation in alphaIIb beta3 integrin.

Integrins are postulated to undergo structural rearrangement from a low affinity bent conformer to a high affinity extended conformer upon activation. However, some reports have shown that a bent conformer is capable of binding a ligand, whereas another report has shown that integrin extension does not absolutely lead to activation. To clarify whether integrin affinity is indeed regulated by the so-called switchblade-like movement, we have engineered a series of mutant αIIbß3 integrins that are constrained specifically in either a bent or an extended conformation. These mutant αIIbß3 integrins were expressed in mammalian cells, and fibrinogen binding to these cells was examined. The bent integrins were created through the introduction of artificial disulfide bridges in the ß-head/ß-tail interface. Cells expressing bent integrins all failed to bind fibrinogen unless pretreated with DTT to disrupt the disulfide bridges. The extended integrins were created by introducing N-glycosylation sites in amino acid residues located close to the α-genu, where the integrin legs fold backward. Among these mutants, activation was maximized in one integrin with an N-glycosylation site located behind the α-genu. This extension-induced activation was completely blocked when the swing-out of the hybrid domain was prevented. These results suggest that the bent and extended conformers represent low affinity and high affinity conformers, respectively, and that extension-induced activation depends on the swing-out of the hybrid domain. Taken together, these results are consistent with the current hypothesis that integrin affinity is regulated by the switchblade-like movement of the integrin legs.

A new disulfide-linked dimer of a single-chain antibody fragment against human CD47 induces apoptosis in lymphoid malignant cells via the hypoxia inducible factor-1α pathway.

CD47 belongs to the immunoglobulin superfamily and is associated with ß-integrins. Recently it was reported that CD47 ligation rapidly induces apoptosis in B-chronic lymphocytic leukemia (CLL) cells. Chronic lymphocytic leukemia is still an incurable hematological malignancy even with the novel therapeutic agents; therefore, new and effective agents for the treatment of CLL in clinical settings are urgently needed. We generated a murine monoclonal antibody against an extracellular domain of human CD47 (designated MABL). Subsequently, we created a disulfide-stabilized dimer of a single-chain antibody fragment of MABL (S-S diabody) to get rid of the adverse effect of MABL such as hemagglutination. In this study, we analyzed the effects of this new antibody on cellular proliferation, and the molecular mechanism of CD47-mediated apoptosis in human lymphoid malignant cells. Treatment with S-S diabody alone induced apoptosis of CD47-positive primary B-CLL and leukemic cells (MOLT-4 and JOK-1). In addition, administration of S-S diabody significantly prolonged the survival of severe combined immunodeficiency (SCID) mice inoculated with JOK-1 cells. In gene expression profiling of the S-S diabody-treated MOLT-4 cells, hypoxia inducible factor (HIF)-1α downstream genes (RTP801 and BNIP3) were upregulated, and the mRNA expression levels of HIF-1α, RTP801 and BNIP3 were increased. Knockdown of HIF-1α by siRNA repressed S-S diabody-induced apoptosis in MOLT4 cells. In conclusion, CD47 will be a molecular target for the treatment of lymphoid malignancies, and S-S diabody might have potential as a novel therapeutic agent for B-CLL.