膜微粒抑制缺氧无血清诱导的骨髓间充质干细胞的凋亡

目的：明确心肌梗死后血液来源的膜微粒（MPs）抑制缺氧无血清诱导的骨髓间充质干细胞（BMSCs）凋亡的作用并探讨其相关机制。方法：利用结扎SD大鼠左冠脉前降支的方法来制作急性心肌梗死模型,然后提取血液中的MPs。提取培养SD大鼠的BMSCs,并建立缺氧无血清的干细胞凋亡模型。分别按照不同浓度（即0.5 μg/mL、1 μg/mL和2 μg/mL）的MPs对干细胞进行预处理,分别利用Hoechst染色、Tunel检测、AnnexinV/PI流式细胞学、Western blot检测caspase-3来揭示MPs抑制BMSCs的凋亡作用,并用Akt信号通路的通路抑制剂AZD5363来初步探讨其抗凋亡的相关机制。结果：大鼠心肌梗死后血液来源的MPs能够有效抑制缺氧无血清诱导的BMSCs的凋亡（P＜0.01）;并且其抗凋亡作用呈现出浓度依赖性,0.5 μg/mL 浓度的MPs亦能达到显著抗凋亡作用（P＜0.05）。其机制主要是通过激活Akt信号通路来实现。结论：心肌梗死后血液来源的MPs能有效抑制缺氧无血清诱导的BMSCs的凋亡。     

寻常型银屑病患者外周血中微粒子的表达

目的：检测微粒子在寻常型银屑病外周血中的表达。方法：高速离心法分离33例寻常型银屑病患者和33名正常人对照外周血T细胞、B细胞及单核细胞来源的微粒子,分别进行细胞特异性单克隆抗体标记,采用流式细胞仪检测三种细胞来源的微粒子数量。结果：银屑病组患者血浆中T淋巴细胞（CD3+）来源的微粒子、单核细胞（CD14+）来源的微粒子和B淋巴细胞（CD19+）来源的微粒子数量分别为（6.6±0.2）×105,（3.9±0.3）×105和（4.1±0.2）×105高于正常对照组的（2.0±0.3）×105,（1.6±0.3）×105和（1.1±0.2）×105.治疗后银屑病组患者微粒子的总数量较治疗前明显减少（P<0.01）。此外,银屑病患者血浆中微粒子水平与PASI评分具有相关性,尤其是T淋巴细胞源性微粒子。结论：微粒子的数量在寻常型银屑病外周血中明显升高,可能在银屑病的发病中起到重要作用。     

肿瘤来源微粒在肿瘤发生发展及诊断治疗中的作用

肿瘤来源微粒(Tumor-derived microparticles,TMPs)是由激活或凋亡的肿瘤细胞释放的直径0.1~1.0μm的细胞外囊泡。它含有其来源细胞的生物活性成分,包括核酸和蛋白质。本文就TMPs在肿瘤发生发展和诊断治疗中作用的研究进展做一综述。     

Increased levels of circulating platelet-derived microparticles in psoriasis:Possible implications for the associated cardiovascular risk

AIM To evaluate platelet activation markers in psoriasis patients, compared to controls, and investigate their association with the inflammatory burden of psoriasis.METHODS Forty psoriatic patients without cardiovascular disease,and 12 healthy controls were subjected to measurement of baseline platelet CD62 P, CD63 and CD42 b expression, platelet-leukocyte complexes, i.e., platelet-monocyte complexes(PMC), platelet-neutrophil complexes(PNC) and platelet-lymphocyte complexes, and concentrations of platelet-derived microparticles(PMPs) using flow cytometry. Both larger-size(0.5-0.9 μm) and smallersize( 0.5 μm) PMPs were determined. Serum interleukin(IL)-12 and IL-17 levels were also measured by enzyme-linked immunosorbent assay. The severity of psoriasis was evaluated by the Psoriasis Area Severity Index(PASI).RESULTS PMP concentrations were significantly higher in psoriasis patients than controls [mean±standard error of mean(SEM): 22±5/μL vs 11±6/μL; P=0.018), for both smaller-size(10±2/μL vs 4±2/μL; P=0.033) and larger-size(12±3/μL vs 6±4/μL; P=0.014) PMPs. Platelet CD62 P, CD63 and CD42 b expression and circulating PMC and PNC were similar between the two groups. Lower circulating PLC were observed in psoriasis patients compared to controls(mean±SEM: 16%±3% vs 23%±6%; P=0.047). Larger-size PMPs were related with IL-12 levels(P0.001) and smaller-size PMPs with both IL-12 and IL-17 levels(P0.001). Total PMPs also correlated with IL-12(P0.001). CD63 expression was positively correlated with both IL-12 and IL-17(P0.05). Increased PASI score was associated with increased levels of larger-size PMPs(r=0.45; P=0.011) and increased CD63 expression(r=0.47; P0.01).CONCLUSION PMPs, known to be predictive of cardiovascular outcomes, are increased in psoriasis patients, and associated with high inflammatory disease burden. Enhanced platelet activation may be the missing link leading to cardiovascular events in psoriatic patients.     

Internalization of microparticles by endothelial cells promotes platelet/endothelial cell interaction under flow

Summary. Background: Microparticles (MPs) released by activated or apoptotic cells increase in number in the blood of subjects with vascular or metabolic diseases and may contribute to thrombotic complications. Objectives: In this study, we investigated whether MPs promoted platelet recruitment to endothelial cells in flow conditions, and by which mechanism. Methods: Human umbilical vein endothelial cells (HUVECs) grown in microslide perfusion chambers were exposed to MPs prepared in vitro from HUVECs, monocytes or platelets. Results: Videomicroscopy of DIOC‐labelled blood perfused at arterial rate on human umbilical vein ECs demonstrated that, irrespective of their cell origin, MPs promoted the formation of platelet strings at the surface of HUVECs. This platelet/endothelial cell interaction was dependent on von Willebrand factor (VWF) expression at the HUVEC surface and involved Glycoprotein Ib and P‐selectin. Interestingly, HUVECs internalized MPs within a few hours through a process involving anionic phospholipids, lactadherin and αvβ3 integrin. This uptake generated the production of reactive oxygen species via the xanthine/xanthine oxidase system (inhibited by allopurinol and the ROCK inhibitor Y‐27632) and the NADPH oxidase (inhibited by SOD). Reactive oxygen species appeared essential for VWF expression at the endothelial cell surface and subsequent platelet/endothelial cell interaction under flow. The pathophysiological relevance of this process is underlined by the fact that circulating MPs from Type I diabetic patients induced platelet/endothelial cell interaction under flow, with an intensity correlated with the severity of the vasculopathy.     

Improving Protein Delivery from Microparticles Using Blends of Poly(DL lactide co-glycolide) and Poly(ethylene oxide)-poly(propylene oxide) Copolymers

Purpose. Microparticles containing ovalbumin as a model for protein drugs were formulated from blends of poly(DL lactide-co-glycolide) and poly(ethylene oxide)-poly(propylene oxide) copolymers (Pluronic). The objectives were to achieve uniform release characteristics and improved protein delivery capacity. Methods. The water- in oil -in oil emulsion/solvent extraction technique was used for microparticle production. Results. A protein loading level of over 40% (w/w) was attained in microparticles having a mean diameter of approximately 5 µm. Linear protein release profiles over 25 days in vitro were exhibited by certain blend formulations incorporating hydrophilic Pluronic F127. The release profile tended to plateau after 10 days when the more hydrophobic Pluronic L121 copolymer was used to prepare microparticles. A delivery capacity of 3 µg OVA/mg particles/ day was achieved by formulation of microparticles using a 1:2 blend of PLG:Pluronic F127. Conclusions. The w/o/o formulation approach in combination with PLG:Pluronic blends shows potential for improving the delivery of therapeutic proteins and peptides from microparticulate systems. Novel vaccine formulations are also feasible by incorporation of Pluronic L121 in the microparticles as a co-adjuvant.     

Prolonged circulation of activated platelets following plasmapheresis

The extent and duration of in vivo platelet activation were determined in 12 volunteer donors undergoing automated plasmapheresis. Expression of P-selectin, activated GpIIb/IIIa, and platelet microparticle formation were measured by flow cytometry on peripheral blood samples obtained immediately before and after plasmapheresis and at 24 hour intervals thereafter for up to 3 days. Although no adverse effects were noted in any donor, immediately after apheresis 3 87% of circulating platelets expressed P-selectin: by 48 hours. 0.5 50% expressed P-selectin; and by 72 hours, all donors studied had fewer than 5% P-selectin expression on circulating platelets. Results were similar for the expression of the activated conformation of GpIIb/IIIa. There was a positive correlation with in vitro P-selectin expression in response to ADP in the pre-apheresis sample and the number of platelet microparticles detected in the donor following plasmapheresis. In addition, the percent expression of P-selectin and activated GpIIb/IIIa in response to ADP was reproducible in each individual studied on five separate occasions (CV ≤ 8%). Platelets activated during plasmapheresis using an automated device may circulate for at least 48 hours, and pre-plasmapheresis response of platelets to the agonist ADP correlated with platelet microparticle formation post-plasmapheresis. © 1994 Wiley-Liss, Inc.     

Augmentation of ultrasound-induced clot disruption by nongas-filled microparticles

The augmentation of ultrasound-induced clot disruption by echocardiographic contrast microbubbles may be a direct mechanical erosive effect of the clot by the microparticles. To further assess this hypothesis, we evaluated the rate and extent of clot disruption by using external ultrasound and nongas-filled microparticles (HAEMACCEL and HAES). Human blood clots were used in this in vitro study. The percent clot reduction using the combination of ultrasound and microparticles was dose dependent and significantly higher than that with microparticles alone.