Mingbao Song

Baseline serum uric acid level as a predictor of cardiovascular disease related mortality and all-cause mortality: a meta-analysis of prospective studies.

OBJECTIVE Serum uric acid (SUA) levels have been used to predict cardiovascular and all-cause mortality event, but the data have yielded conflicting results. We investigated whether SUA was an independent predictor for cardiovascular or all-cause mortality with prospective studies by meta-analysis. METHODS Pubmed and Embase were searched without language restrictions for publications available till April 2013. Only prospective studies on cardiovascular or all-cause mortality related to SUA levels were included. Pooled adjust relative risk (RR) and corresponding 95% confidence intervals (CI) were calculated separately for the highest vs. lowest category or the lowest vs. middle category. RESULTS For the highest SUA, eleven studies with 172,123 participants were identified and analyzed. Elevated SUA increased risk of all-cause mortality (RR 1.24; 95% CI 1.09-1.42) and cardiovascular mortality (RR 1.37; 95% CI 1.19-1.57). Subgroup analyses showed that elevated SUA significantly increase the risk of all-cause mortality among men (RR 1.23; 95% CI 1.08-1.42), but not in women (RR 1.05; 95% CI 0.79-1.39). Risk of cardiovascular mortality appeared to be more pronounced among women (RR 1.35; 95% CI 1.06-1.72). The association between extremely low SUA and mortality was reported in three studies; we did not perform a pooled analysis because of high degree of heterogeneity in these studies. CONCLUSIONS Baseline SUA level is an independent predictor for future cardiovascular mortality. Elevated SUA appears to significantly increase the risk of all-cause mortality in men, but not in women. Whether low SUA levels are predictors of mortality is still inconclusive.

An essential role for stromal interaction molecule 1 in neointima formation following arterial injury

AIMS There is evidence to suggest that stromal interaction molecule 1 (STIM1) functions as a Ca2+ sensor on the endoplasmic reticulum, leading to transduction of signals to the plasma membrane and opening of store-operated Ca2+ channels (SOC). SOC have been detected in vascular smooth muscle cells (VSMCs) and are thought to have an essential role in the regulation of contraction and cell proliferation. We hypothesized that knockdown of STIM1 inhibits VSMC proliferation and suppresses neointimal hyperplasia. METHODS AND RESULTS We examined the effect of the knockdown of STIM1 using a rat balloon injury model and cultured rat aortic VSMCs. Interestingly, knockdown of rat STIM1 by adenovirus delivery of small interfering RNA (siRNA) significantly suppressed neointimal hyperplasia in a rat carotid artery balloon injury model at 14 days after injury. The re-expression of human STIM1 to smooth muscle reversed the effect of STIM1 knockdown on neointimal formation. Rat aortic VSMCs were used for the in vitro assays. Knockdown of endogenous STIM1 significantly inhibited proliferation and migration of VSMCs. Moreover, STIM1 knockdown induced cell-cycle arrest in G0/G1 and resulted in a marked decrease in SOC. Replenishment with recombinant human STIM1 reversed the effect of siRNA knockdown. These results suggest STIM1 has a critical role in neointimal formation in a rat model of vascular injury. CONCLUSION STIM1 may represent a novel therapeutic target in the prevention of restenosis after vascular interventions.

SDF-1α involved in mobilization and recruitment of endothelial progenitor cells after arterial injury in mice

BACKGROUND Endothelial progenitor cells (EPCs) can be mobilized by cytokines and recruited to sites of neovascularization and neointima, where they differentiate into mature endothelial cells. It is thought that stromal cell-derived factor-1alpha (SDF-1alpha) is involved in ischemia-mediated mobilization and homing of EPCs and in vascular injury-mediated mobilization and homing of vascular smooth muscle progenitor cells. It is unclear if SDF-1alpha plays a similar role in the mobilization and recruitment of EPCs after vascular injury. METHODS AND RESULTS SDF-1alpha was detected by reverse transcriptase-polymerase chain reaction and Western blot in the carotid arteries of mice at different times after wire-induced injury. SDF-1alpha expression was evident at 1 day and peaked at 3 days after arterial injury. In an ELISA test, a rise in the plasmatic concentration of SDF-1alpha and a significant reduction of SDF-1alpha bone marrow (BM) concentration were noticed at different times after injury (Days 1, 3, and 7). Fluorescence-activated cell sorting analysis revealed that the amount of circulating EPCs was increased shortly after induction of vascular injury and persisted for up to 7 days. In SDF-1alpha antibody-treated mice, only a small rise in the amount of circulating EPCs was noted at 1 day. En-face microscopy and immunohistochemical analysis showed that systemic injection of EPCs after vascular injury demonstrated their recruitment to the sites of endothelial denudation, where they could adopt an endothelium-like phenotype and accelerate reendothelialization of the injured arteries. Fewer CXCR4 (receptor of SDF-1)-blocked EPCs could home to the sites of endothelial denudation, and accelerated reendothelialization was not observed in this group. Treatment of mice after carotid injury with a neutralizing SDF-1alpha monoclonal antibody for 2 weeks reduced reendothelialization area. CONCLUSION We demonstrated for the first time that SDF-1alpha plays an important role in reendothelialization after vascular injury in mice. This contribution appears to be attributable to SDF-1alpha-dependent mobilization and recruitment of circulating EPCs.

Transfection of HGF gene enhances endothelial progenitor cell (EPC) function and improves EPC transplant efficiency for balloon-induced arterial injury in hypercholesterolemic rats

Risk factors for coronary heart disease can reduce the number of endothelial progenitor cells (EPCs) and impair EPC function, thus hindering their utility in the treatment of cardiovascular diseases. In the present study, we began exploring the feasibility of genetic modification of EPCs with hepatocyte growth factor (HGF) to counter the effects of these risk factors and enhance the biological functions of EPCs. The effects of HGF transfection on proliferation, migration and angiogenesis of EPCs were investigated. Additionally, the role of ERK1/2 in this process was evaluated through the observation of ERK1/2 and ERK1/2 phosphorylation as well as by pharmacological analysis. Finally, we evaluated the effect of HGF-transfected EPCs (HGF-EPCs) on neointima formation after balloon-induced arterial injury in hypercholesterolemic rats. Our data showed that EPCs transfected with the HGF gene released high levels of soluble HGF protein, which were maintained for at least nine days. Transfection with HGF also enhanced the proliferative, migratory and angiogenic capabilities of EPCs, and promoted the activation of ERK1/2 without affecting its expression. ERK1/2 blockade by the chemical inhibitor PD98059 partially inhibited these effects. In hypercholesterolemic rats, HGF-EPCs homed to the site of vascular injury at a significantly higher rate than did EPCs without the exogenous HGF gene. Furthermore, systemically applied HGF-EPCs were more effective in decreasing neointima formation and increasing re-endothelialization. These data suggest that gene delivery combined with EPC transplant may be a practical and promising therapy for the prevention of neointimal formation after vascular injury.

Blockade of connexin 43 hemichannels reduces neointima formation after vascular injury by inhibiting proliferation and phenotypic modulation of smooth muscle cells.

Connexins 43 (Cx43) plays a key role in neointimal formation after vascular injury, but the mechanism still needs to be further explored. We hypothesized that the gap junction-dependent function of Cx43 to mediate intercellular communication has a crucial role in the development and progression of vascular diseases. The effect of intercellular communication mediated by Cx43 hemichannels on neointimal formation after vascular injury was investigated. Cx43 was overexpressed or knockdown in rat vascular smooth muscle cell (SMC) by transfection pcDNA-Cx43 plasmid or small interfering RNA (siRNA) against Cx43 (siCx43). SMC proliferation and marker genes expression after Cx43 alteration and blockade of the Cx43 hemichannel were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and RT-PCR. The effect of carbenoxolone on neointimal formation was investigated in carotid artery injured rat model. We demonstrated that overexpression of Cx43 promoted SMC proliferation, meanwhile, mRNA expression level of smooth muscle α-actin and calponin, which were important markers of SMC in a contractile state, were down-regulated in smooth muscle. Knockdown of Cx43 inhibited SMC proliferation but increased SMC marker genes expression level. Carbenoxolone (50 μM) improved SMC contractile differentiation and inhibited its proliferation. Our data showed that carbenoxolone reduced neointimal formation after carotid artery injury. In summary, blockade of intercellular communication via Cx43 hemichannels reduces neointimal formation after vascular injury by inhibiting proliferation and phenotypic modulation of SMCs.

The matrix protein CCN1 (CYR61) promotes proliferation, migration and tube formation of endothelial progenitor cells.

Neovascularization and re-endothelialization relies on circulating endothelial progenitor cells (EPCs), but their recruitment and angiogenic roles are subjected to regulation by the vascular microenvironment, which remains largely unknown. The present study was designed to investigate the effects of mature ECs and matrix protein CCN1 on the properties of EPCs. In a coculture system, effects of ECs on proliferation, migration and participation in tube-like formation of EPCs were evaluated, and functional assays were employed to identify the exact role of CCN1 in EPCs vitality and function. We demonstrated that ECs, as an indispensable part of the cellular milieu, significantly promoted the proliferation, migration and tube formation activities of EPCs, and more importantly, CCN1 was potentially involved in such effects of ECs. Expression of CCN1 in EPCs was significantly increased by serum, VEGF, ECs-cocultivation and ECs conditioned medium. Moreover, Ad-CCN1-mediated overexpression of CCN1 directly enhanced migration and tube formation of EPCs, whereas silencing of endogenous CCN1 in EPCs inhibits cell functions. Furthermore, CCN1 induced the expressions of chemokines and growth factors, such as MCP-1 and VEGF, suggesting a complex interaction between those proangiogenic factors. Our data suggest that matrix protein CCN1 may play an important role in microenvironment-mediated biological properties of EPCs.

Beneficial effects of a polysaccharide from Salvia miltiorrhiza on myocardial ischemia–reperfusion injury in rats

In the present study, one water-soluble polysaccharide (SMP1) was isolated from the roots of Salvia miltiorrhiza. The cardio-protective potential of SMP1 was studied in the ischemia-reperfusion (I/R) model of rats in vivo. Results showed that 30 min of left anterior descending coronary artery occlusion (LAD) followed by 4 h of reperfusion markedly decreased myocardial superoxide dismutase (SOD), Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities and increased myocardial malondialdehyde (MDA) level and serum activities of creatine kinase (CK) and lactate dehydrogenase (LDH) in I/R rats. An increase in infarct size and high apoptosis index of cardiac cell were also observed in IR rats. Administration of SMP1 400 and 800 mg/kg significantly reversed these biochemical parameters in the I/R rats to the normal levels in sham control rats. The infarct sizes and the percent of TUNEL-positive cells were found significantly decreased in SMP1-treated groups compared to I/R rats. Taken together, the present study clearly suggests SMP1 has a protective effect against myocardial I/R injury in rats by ameliorating oxidative stress and inhibiting myocardial apoptosis.

Over-expression of hepatocyte growth factor in smooth muscle cells regulates endothelial progenitor cells differentiation, migration and proliferation

BACKGROUND Endothelial repair is one of key events after vascular injury. The mechanisms by which hepatocyte growth factor (HGF) and endothelial progenitor cells (EPCs) may be responsible for re-endothelialization of injured blood vessel wall are poorly understood. METHODS Primary culture SMCs were transfected with pcDNA3.0-HGF followed by G418 selection, one of G418-resistant colonies in well was picked, propagated and used as donor cells for further experiments. HGF and VEGF expression in SMCs were detected with western blot and enzyme linked immunosorbent assays (ELISA). Rat EPCs were cultured in untreated, pcDNA3.0 and pcDNA3.0-HGF transfected SMCs conditioned medium with or without anti-VEGF or exogenous recombinant HGF addition. eNOS, KDR and CD31 expression in EPCs was determined by real-time quantitative polymerase chain reaction (RT-qPCR) or flow cytometry; EPCs migration and proliferation were measured by using a modified Boyden chambers and MTT assay respectively. RESULTS Abundant and stable expression of HGF was found in G418-resistant colony-derived SMCs. VEGF expression significantly increased in HGF transfected SMCs. Exogenous recombinant HGF (rHGF) markedly up-regulated eNOS mRNA expression in EPCs and promoted EPCs migration and proliferation, but no significant changes were found in KDR and CD31 mRNA expression. HGF transfection in SMCs was more effective than exogenous HGF for EPCs differentiation, proliferation and migration. CONCLUSIONS Over-expression of HGF in SMCs can be helpful for promoting EPCs differentiation, increasing EPCs migration and proliferation. It may be responsible for angiogenesis of arteriosclerosis lesions and useful for blood vessel tissue engineering.

Hepatocyte growth factor protects endothelial progenitor cell from damage of low-density lipoprotein cholesterol via the PI3K/Akt signaling pathway

Risk factors for coronary heart disease including low-density lipoprotein (LDL) cholesterol can reduce the number and activity of endothelial progenitor cells (EPCs), thereby hindering their usefulness for treating cardiovascular disease in transplants. The aim of this study was to investigate whether hepatocyte growth factor (HGF) can protect EPCs from the inhibition caused by LDL cholesterol. EPCs derived from mouse bone marrow were isolated and cultured in medium supplemented with different concentrations of LDL cholesterol. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, modified Boyden chambers and flow cytometry were used to evaluate EPC proliferation, migration and apoptosis. The role of Akt in this process was also evaluated through observing the expressions of total Akt and Akt phosphorylation, and pharmacological analysis. Our results indicate that LDL cholesterol inhibits the proliferation and migration of EPCs, and induces their apoptosis. However, HGF improves the activity of EPCs inhibited by LDL cholesterol, and it simultaneously decreases EPC apoptosis induced by LDL cholesterol. Blockade of phosphoinositide-3 kinase (PI3K) by Ly294002 attenuates the effect of HGF. Furthermore, our experiments suggest that HGF increases the level of phosphorylated Akt in EPCs rather than Akt. However, PI3K inhibitor reduces the increase of phosphorylated Akt level induced by HGF. These findings suggest HGF promotes endothelial progenitor cells migration, proliferation and survival impaired by low-density lipoprotein cholesterol via the PI3K/Akt signaling pathway.

Inhibitor of DNA binding-1 promotes the migration and proliferation of endothelial progenitor cells in vitro.

Migration and proliferation of endothelial progenitor cells (EPCs) are the key mechanisms in re-endothelialization after vascular injury. Inhibitor of DNA binding-1 (Id1) function has been linked to the proliferation, migration, and senescence of cells, and studies have shed light on the relationship between Id1 and the biological functions of EPCs. On the basis of the available data concerning Id1 and the behavior of EPCs, we hypothesized that Id1 was an important regulator in modulating the migration and proliferation of EPCs. Culture of spleen-derived EPCs was done as previously described. Id1 was presented at low levels in EPCs. Id1 was localized predominantly in the cytoplasm, and was rapidly upregulated by stimulation with serum and vascular endothelial growth factor. The migration and proliferation of EPCs were extensively improved by overexpression of adenovirus-mediated exogenous Id1 and inhibited by silencing of endogenous Id1 in EPCs. These results suggest that Id1 has a direct role in regulation of the migration and proliferation in EPCs.