Circulating circRNA expression profile and its potential role in late recurrence of paroxysmal atrial fibrillation post catheter ablation.

BACKGROUND: Catheter-based pulmonary vein isolation (PVI) is an effective and well-established intervention for symptomatic paroxysmal atrial fibrillation (PAF). Nevertheless, late recurrences of atrial fibrillation (LRAF) occurring during 3 to 12 months are common, and the underlying mechanisms remain elusive. Circular RNAs (circRNAs) in atrial tissue have been linked to the pathophysiological mechanisms and progression of PAF in a few studies. However, their expression patterns in peripheral blood and regulatory function in LRAF are not clear. METHODS: In the present study, the expression profile of circulating circRNAs in three paired nonvalvular PAF patients with or without LRAF was investigated by high-throughput sequencing and validated by quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and circRNA/miRNA regulatory network, were performed to predict the functions and potential regulatory roles of differentially expressed (DE) circRNAs. RESULTS: A total of 12,834 circRNAs, comprising 5,491 down-regulated and 7,343 up-regulated circRNAs, were found to be DE in blood smaples from the two groups in peripheral blood between LRAF and non-recurrence control individuals. The most enriched GO categories in terms of molecular function, biological process, and cellular component features were catalytic activity, cellular metabolic process, and intracellular part, respectively. The KEGG enrichment study revealed that the most important metabolic process controlled by DE circRNAs is endocytosis. In the circRNA/microRNAs interaction network, four up-regulated circRNAs (hsa_circ_0002665, hsa_circ_0001953, hsa_circ_0003831, and hsa_circ_0040533) and one down-regulated circRNA (hsa_circ_0041103) were predicted to play potential regulatory roles in the pathogenesis of LRAF. CONCLUSIONS: This investigation discovered the expression pattern of circulating circRNAs that is indicative of PAF late recurrence, which may serve as risk markers or therapeutic targets for LRAF after PVI.

[Microparticles, stem cells' new mechanism for tissue repair?].

Though stem cell transplantation has been confirmed to be useful in repairing aging and diseased tissues, the underlying mechanism remains elusive. In addition to soluble molecules, cells-derived membrane microparticles (MPs) are considered as new mediators served in cross-talk communication among cells. MPs are tiny membrane coated subcellular vesicles released by a variety of cell types including stem cells. MPs may interact with target cells through specific receptor-ligand interactions and transfering proteins, bioactive lipids, mRNA and miRNA. Composition and function of stem cells derived MPs are highlighted in recent years. Here, we give an overview of MPs'composition, vesiculation and liberation mechanism, roles involved in communication exchages, and research progress in stem cells derived MPs. The report here might provide some novel information to highlight the stem cells therapy.

[Mesenchymal Stem Cells Stimulated by Growth Factors Release Exosomes with Potent Proangiogenic Activity].

OBJECTIVE: To explore the proangiogenic activity of exsomes released by human umbilical cord mesenchymal stem cells (MSCs) stimulated by erythropoietin and platelet-derived growth factor BB (PDGF-BB). METHODS: Human umbilical cord-derived MSCs were seeded and maintained in culture overnight. The media were then replaced by alpha-MEM containing EPO (1 U/ml) and/or PDGF-BB (50 ng/ml), and the culture was maintained for 72 hours. The exosomes from the culture supernatants were isolated with a routine ultra-catrifagation method. Flow cytometric analysis was performed to identify the origin of the exosomes, and their morphological features were observed by using a transmission electron microscopy. The exosomes were added at a concentration of 10 µg/ml into the culture system of human umbilical cord vein endothelial cells. MTT assay was used to evaluate the proliferative status. The Matrigel assay was used to observe the formation of net-work structures which were calculated after culture for 12 hours. RESULTS: Flow cytometric analysis showed that microparticles released by human umbilical cord MSCs expressed CD9, CD63 and CD81, which was in accordance with the surface molecular features of exosomes. Under an electron microscope, the exosomes took the featured cystic shape. The protein contents of exosomes released by untreated, EPO-stimulated, PDGF-BB-stimulated and EPO plus PDGF-BB stimulated MSCs (108 cells) were 256±124 µg, 1021±392 µg, 830±265 µg and 2207±733 µg, respectively. The results revealed that MSCs treated by EPO and PDGF-BB released significantly higher amounts of exosomes (P<0.01). MTT assay proved that the exosomes from EPO and PDGF-BB treated MSCs had more potent proliferation-promoting activity on human umbilical cord vein endothelial cells than those from untreated MSCs. The Matrigel assay showed that the numbers of capillary-like structures in untreated, EPO-, PDGF-BB and EPO plus PDGF-BB-treated groups were 2.6±0.84, 4.6±1.57, 4.2±0.78 and 6.3±1.34 per high power objective. Treatment with EPO or PDGF-BB dramatically enhanced the numbers of capillary liue structure, compared with that of untreated group (P<0.01) and those in EPO and PDGF-BB combination group was significantly greater than those of EPO or PDGF-BB group (P<0.01). CONCLUSION: EPO and PDGF-BB can stimulate MSCs to release exosomes with more potent proangiogenic activity.

Cancer risk in older people receiving statin therapy: a meta-analysis of randomized controlled trials.

BACKGROUND: Although statins are well tolerated by most aged people, their potential carcinogenicity is considered as one of the biggest factors limiting the use of statins. The aim of the present study was to determine the risk of cancer in people aged over 60 years receiving statin therapy. METHODS: A comprehensive search for articles published up to December 2015 was performed, reviews of each randomized controlled trials (RCTs) that compared the effects of statin mono-therapy with placebo on the risk of cancer in people aged > 60 years were conducted and data abstracted. All the included studies were evaluated for publication bias and heterogeneity. Pooled odds ratios (OR) estimates and 95% confidence intervals (CIs) were calculated using the random effects model. RESULTS: A total of 12 RCTs, involving 62,927 patients (31,517 in statin therapy group and 31,410 in control group), with a follow-up duration of 1.9-5.4 years, contributed to the analysis. The statin therapy did not affect the overall incidence of cancer (OR = 1.03, 95% CI: 0.94-1.14, P = 0.52); subgroup analyses showed that neither the variety nor the chemical properties of the statins accounted for the incidence of cancer in older people. CONCLUSIONS: Our meta-analysis findings do not support a potential cancer risk of statin treatment in people over 60 years old. Further targeted researches with a longer follow-up duration are warranted to confirm this issue.

[Experimental study of effect of carvedilol on myocardial collagen network remodeling after acute myocardial infarction in rats].

OBJECTIVE: To investigate the effects of carvedilol, irbesartan and their combination on myocardial collagen network remodeling after acute myocardial infarction (AMI) in rats. METHODS: Twenty-four hours after ligating left anterior descending coronary artery, 35 surviving AMI male Sprague-Dawley rats were randomly assigned to control (n=8), carvedilol (n=9, 10 mg.kg(-1).d(-1)), irbesartan (n=9, 45 mg.kg(-1).d(-1)), and carvedilol (10 mg.kg(-1).d(-1)) plus irbesartan (45 mg.kg(-1).d(-1), n=9) groups. Sham operating group was comprised of 8 rats without coronary artery ligation as controls. After 8 weeks of administration of the drug by gastric gavage, hemodynamics and left ventricular function were measured, then the rat hearts were fixed, sectioned, and stained with Sirius red, and pathologically analyzed using polarized light. The total collagen volume density fraction (CVF) and type I and III CVF in the infarcted and noninfarcted zone (IZ/NIZ) were measured by computer-assisted image analysis system. RESULTS: There were no significant differences in myocardial infarction size among the four AMI groups (40.02%-44.70%, P>0.05). Compared with the sham operation group, left ventricular (LV) end diastolic pressure (LVEDP), left and right ventricular relative weight (LVRW/RVRW), the total CVF and the CVF of type I and III in the IZ and NIZ were all significantly higher (P<0.05 or P<0.01), and in contrast, blood pressure, left ventricular systolic pressure (LVSP), the left ventricular pressure maximal rate of rise and fall (+/-dp/dt max) and their adjustment by LVSP (+/-dp/dt max/LVSP) were significantly decreased (P<0.05 or P<0.01). Compared with the control group, LVEDP, LVRW, RVRW, the total CVF and the CVF of type I and III in the NIZ were all significantly decreased (P<0.05 or P<0.01), while +/-dp/dt max and +/-dp/dt max/LVSP were all significantly increased (all P<0.01) in the carvedilol, irbesartan and their combination therapy groups. CONCLUSION: Carvedilol, irbesartan and their combination can all effectively decrease collagen deposition in the NIZ of left ventricle, prevent left ventricular remodeling after AMI in rats, improve hemodynamics and LV function.

Should antiplatelet therapy be interrupted in drug eluting stent recipients throughout the periendoscopic period? A very late stent thrombosis case report and review of the literature.

In-stent thrombosis after cessation of antiplatelet medications in patients with drug-eluting stents (DES) is a significant problem in medical practice, particularly in the perioperative period. We report a case of an 87-year-old man with a medical history of hypertension, coronary artery disease and chronic atrophic gastritis. Very late thrombosis of a sirolimus-eluting stent occurred 1207 days after implantation, seven months after discontinuation of clopidogrel, and the interruption of aspirin 13 days in preparation of an elective endoscopic gastrointestinal procedure presented with acute myocardial infarction. The patient was treated with thrombectomy and successfully revascularized with superimposition of two sirolimus-eluting stents. Medications administered in the catheterization laboratory included low molecular weight heparin and nitroglycerin. Flow was defined as grade 2 according to the thrombolysis in myocardial infarction scale. Electrocardiogram after the procedure revealed persistent, but decreased, ST-segment elevation in the anterolateral leads. The patient recovered and was discharged on aspirin and clopidogrel indefinitely. There was no cardiac event during the two year follow-up period. This case underlines the importance of maintaining the balance of thrombosis and bleeding during perioperation of non-cardiac procedure and the possible need for continuation of aspirin therapy during periendoscopic procedures among patients with low bleeding risks who received DES.

Rare occurrence of simultaneous coronary artery perforation and intracoronary thrombus formation following angioplasty.

Both coronary artery perforation and intracoronary thrombus formation are life-threatening complications of percutaneous coronary interventions, which rarely occur simultaneously during angioplasty. We herein report a case of stent-related, left circumflex artery perforation, and subsequently acute left main artery thrombosis after the leakage was embolized with 7 microcoils. Intracoronary thromboectomy and systemic anticoagulant therapy were carefully used with good results. This case also represents some of our uncertainties regarding the best management of the patient.

[Mesenchymal stem cells release membrane microparticles in the process of apoptosis].

Though mesenchymal stem cells (MSC) have been clinically used to repair a variety of damaged tissues, the underlying mechanisms remain elusively as the majority of the ex vivo expanded MSC die shortly after transplantation. To explore the mechanism in which the death cells play tissue repair effect, apoptosis of rat bone marrow MSC was induced by culturing cells in the conditions of hypoxia or/and serum-free medium, and the subcellular structures in the supernatants were analyzed. The results showed that apoptosis occurred in the presence of either hypoxia or serum-free condition as well, and the apoptotic proportion reached up to (17.44 ± 2.15) after the cells were treated by hypoxia plus serum free culture for 72 hours. The flow cytometric analysis of the sub-cellular substances harvested by ultracentrifugation of the supernatants found that the MSC released substantial amount of membrane microparticles into the supernatants, which expressed CD29, CD44A and Annexin-V-binding phosphatidylserine. It is concluded that the MSC can release membrane microparticles after induction, the amount of these membrane microparticles was around 15-fold of the parent cell numbers. The membrane microparticles is the mediators in the cross-talk between the transplanted cells and their surrounding tissues. This study provides some novel information for the mechanisms of MSC therapy.

Association of glomerular filtration rate with arterial stiffness in Chinese women with normal to mildly impaired renal function.

OBJECTIVE: Both decreased glomerular filtration rate (GFR) and arterial stiffness were considered as risk factors for atherosclerosis. Previous studies have suggested the association between central arterial stiffness and the degree of GFR loss. Whether decreased GFR contributes to peripheral artery stiffness remains controversial. Moreover, data analyzed from a cohort of Chinese women are rare. Our aim was to explore the relationship between GFR and regional arterial stiffness in Chinese women. METHODS: In this cross-sectional study, we randomly recruited 1131 adult women residents with GFR ≥ 60 mL/min per 1.73 m(2) estimated by the Chinese Modification of Diet in Renal Disease equation from three large communities. Central and peripheral arterial stiffness were estimated simultaneously by measuring carotid-femoral pulse wave velocity (PWVcf) and carotid-radial PWV (PWVcr) using a validated automatic device. Augmentation Index at heart rate 75 beats/minutes (AIx-75) was measured by pulse wave analysis as a composite parameter reflecting both large and distal arterial properties. RESULTS: The mean estimated GFR (eGFR) of the study group was 100.05 ± 23.26 mL/minute per 1.73 m(2). Subjects were grouped by tertiles of eGFR level. PWVcf and AIx-75 increased ongoing from the top to the bottom eGFR tertile, while the values of PWVcr were comparable. Both univariate Pearson correlations and multiple stepwise regression analyses showed that eGFR significantly correlated to PWVcf, but not to PWVcr and AIx-75. CONCLUSIONS: In Chinese women with normal to mildly impaired renal function, decreased eGFR affected carotid-to-femoral rather than carotid-to-radial stiffening. This provides rational to conduct future prospective studies to investigate predictors of atherosclerosis in this population.

[Mesenchymal stem cells exist in the compact bones from four species of mammals].

The biological properties of cultured mesenchymal stem cells (MSC) have been intensively investigated, while there is still a paucity of information about the definite in vivo sites that harbor these stem cells due to the lack of specific surface markers. Previous data have demonstrated that human and murine MSC can be isolated from the compact bones. To investigate if it is the case for other species, the femurs from Wistar rats, Beagles, C57 mice and New Zealand rabbits were collected, minced and digested with collagenase type I. The digested bone fragments were seeded into the medium for human bone marrow culture after removal of the suspended cells in the digestion. The results showed that the fibroblast-like cells were observed to migrate from the bone fragments after several days of culture, and they gradually formed an adherent confluent layer. The adherent cells could be passaged and expressed homogenously the mesenchymal cell marker vimentin. Differentiation assays showed that these cells had the capacity to differentiate into osteoblasts and adipocytes. In conclusion, the results here provide new information for the further investigations on the in vivo biological features of MSC in the context of the simplicity of the compact bone structure.

[In vivo tracing of transplanted bone marrow mesenchymal stem cells with bioluminescence imaging].

Mesenchymal stem cell (MSC)-based cell therapy has shifted into clinical trials to repair the damage of various tissues. In this setting, the survival of the transplanted cells contributes critically to the therapeutic effectiveness. To investigate the in vivo tracing of MSCs, a recombinant retroviral vector carrying firefly-luciferase reporter gene [pL (FLUC) SN] was constructed and several GPE+86 cell clones that stably expressed fluc were selected. The retroviral supernatants were collected and used to transfect MSC derived from C57 mice. The cells were then screened with G418 and the expression of the exogenous gene was identified by luciferase enzyme activity analysis. Labeled mouse MSCs (2x10(6)) were injected into skeletal muscles, and the in situ expression was noninvasively tracked by in vivo bioluminescence imaging for 1, 3 and 6 days after transplantation. The results showed that the survival rates of the grafted cells dropped sharply with time, they were 57.2+/-11.7%, 8.6+/-2.5% and 5.4+/-3.1% on day 1, 3 and 6 after transplantation, and no fluorescent signals above background were detected on day 10. It is concluded that the method described above could be used for in vivo tracing of grafted cells. Furthermore, MSCs could not survive even transplanted into the none-ischemic skeletal muscles.