Abstract:Acute coronary syndrome (ACS) is a group of clinical syndromes with high morbidity and mortality worldwide. Increasing evidence suggest that plaque erosion with an intact fibrous cap is one of the major causes responsible for ACS. Basic experiments have shed light on the unique molecular characteristics of plaque erosion. It has been indicated that plaque erosion starts with the changes of blood flow disturbance-induced endothelial cell damage, resulting in loss of basement membrane integrity and endothelial cell desquamation, with consequent formation of neutrophil extracellular traps and thrombosis. This review will discuss the molecular characteristics of atherosclerotic plaque erosion and translational research needed for future precision medicine in patients with plaque erosion.

Abstract:Aim Cell culture system with glass-like rigid substrates is currently used to detect cell biological behaviors. However, the impact of the stiffness of tissue-like soft substrates on stem cell morphology and differentiation is rarely considered in cell-based cardiac repair. This work aimed to access the effects of myocardium-like soft culture substrates on the specification of CD34+ as well as CD34－ subsets along endothelial lineage in comparison with conventional glass-like rigid substrates. Methods Elastic modulus (E, a material property that describes the stiffness or elasticity) of normal myocardium was measured using atomic force microscopy (elastic modulus≈15 kPa). Myocardium-like soft culture substrates were prepared using polyacrylamide gel with a similar stiffness to normal myocardium. Meanwhile, cell culture system with glass-like rigid substrates (elastic modulus >1 GPa) was used as the control. Mouse bone marrow-derived CD34+ and CD34－ cells were collected by density gradient centrifugation and magnetic activated cell sorting (MACS). The isolated cells were cultured both on myocardium-like soft matrix and glass rigid substrate (E>1 GPa). At day 7 of culture, the surface markers of endothelial lineage, cell morphology, and cytoskeleton were observed by laser scanning confocal microscopy. Results Regardless of the substrate stiffness, mouse bone marrow-derived CD34+ cell subsets exhibited higher percentage of double-positive cells for dil-labelled acetylated-low density lipoprotein (Dil-ac-LDL) uptake and FITC-labelled ulex europaeus agglutinin I lectin (FITC-UEA-1) binding, and higher expression of endothelial lineage markers, CD31, vWF, Flk-1, and VE-cadherin than CD34－ subsets. Moreover, in terms of the difference in cell specification efficacy between CD34+ subsets and CD34－ subsets, myocardium-like soft substrate showed a more potent induction capacity than conventional glass-like rigid substrate. It might partially result from more stressful F-actin fibers and more abundant focal adhesions of CD34+ cell subsets on myocardium-like soft substrates. Conclusions Myocardium-like soft substrate was capable of inducing potently cell specification of CD34+ subsets compared with glass-like rigid substrate. It speculated that tissue-like soft substrate might be a more optimal culture system for detecting the specification of stem cells in vitro.

Abstract:Matrix metalloproteinase-9 (MMP-9), a proteinase containing Zn2+ mostly expressed in macrophages, has involved in synthesis and degradation of extracellular matrix, as well as regulation of inflammatory mediators, which facilitated the initiation and exacerbation of atherosclerosis and vascular wall remodeling, leading to the occurrence of cardiovascular events. In this review, we focused on the research progress of MMP-9 in atherosclerosis and introduced the predicting value of MMP-9 for acute myocardial infarction and cardiac remodeling of post-myocardial infarction.

Abstract:Aim To investigate the pathological changes of vascular remodeling and collagen in spontaneously hypertensive rats（SHR） and the effect of treatment by Xuezhikang. Methods 30 male SHR at 8-week-old were randomly divided into three groups （n10 each）: Xuezhikang low dose group （XZK-L group,Xuezhikang 20 mg/（kg·d））,Xuezhikang high dose group （XZK-H group,Xuezhikang 200 mg/（kg·d）） and placebo group,sex and age matched Wistar rats （control group,n10） were also designed. 8 weeks after intragastric administration,the levels of serum matrix metalloproteinase-9（MMP-9） and tissue inhibitors of metalloproteinase-1（TIMP-1） were measured by enzyme linked immunosorbent assay （ELISA）. The thoracic aortas were collected for hematoxylin-eosin （HE） stain to detect vascular wall thickness and Wall-to-lumen area ratio （W/L）. The aortic collagen was showed by Masson trichrome stain. The thoracic aortas were observed by immunohistochemistry to detect the expressions of MMP-9 and TIMP-1. Quantitation of the protein content of MMP-9 and TIMP-1 was assessed by computerized planimetry in the aortic media in immunohistochemically stained slides by using Image-Pro Plus 6.0. Results The level of serum MMP-9 in placebo group was significantly increased compared with XZK-H group and control group （P<0.05）. The levels of serum TIMP-1 in the SHR groups were higher than control group（P<0.01）. There was no significance of the levels of TIMP-1 in all SHR group （P>0.05）. Aortas of SHR showed wall thickening,increasing wall-to-lumen area ratio and collagen,disordered fibres. The thickness of vascular wall and W/L ratio of SHR were significantly higher than those of Wistar rats （P<0.05）. Arteries in XZK group showed less collagen in aortic wall than that of placebo group,especially the XZK-H group was near to the control group. In the placebo group,MMP-9 protein expression was significantly increased in the thoracic aorta compared with control group and XZK-H group（P<0.05）. However,the level of TIMP-1 had no significance in the four groups （P>0.05）. Conclusions Hypertensive vascular remodeling shows elevated level of MMP-9 and collagen deposition. While Xuezhikang can inhibit the elevated MMP-9 and collagen deposition,improve vascular remodeling in hypertension.

Abstract:Aim To study the effects of phentolamine on myocardial extracellular matrix of cardiac remodeling induced by norepinephrine in rats. Methods Twenty-four male SD rats were randomly divided into control group, norepinephrine group （model group） and norepinephrine＋phentolamine group （treatment group）. Left ventricular structure and function among groups of rats were measured by echocardiography. Extracellular matrix remodeling was evaluated by morphological examination, stained with Van-Gieson （VG）. The content of hydroxyproline in the tissue of myocardium was measured. The protein expression of matrix metalloproteinase- 2 （MMP-2） and collagen Ⅰ were examined by immunohistochemical analysis. Results Compared with control group, left ventricular hypertrophy, the hydroxyproline content, collagen volume fraction （CVF） and protein expression of MMP-2 and collagen Ⅰ was significantly higher in the model group rats （P＜0.01）. In treatment group rats, myocardial hypertrophy obviously improved, hydroxyproline, CVF reduced, protein expression of MMP-2 and collagenⅠdecreased （P＜0.05）. Conclusion Phentolamine can prevent the cardiac hypertrophy and extracellular matrix remodeling, which was associated with the attenuation of myocardial MMP-2and collagen Ⅰ.

Abstract:Aim To study the effect of serum interleukin-18 （IL-18） in human acute myocardial infarction and its possible mechanism in the process of plaque rupture. Methods Serum levels of IL-18 and MMP-9 proteins were determined using commercially available enzyme-linked immunoassays in each group: acute myocardial infarction （AMI） group, stable angina pectoris （SAP） group and heathy control group （n＝20, respectively）. Flow cytometry was applied to assess extracellular matrix metalloproteinase inducer （EMMPRIN） expression on the surface of monocytes of each group. In vitro experiment, quantitative real-time polymerase chain reaction （QRT-PCR） and Western blot were performed to compare EMMPRIN expression of monocytes cultured in presence and absence of IL-18. Results In patients with AMI, serum level of IL-18 and MMP-9 and expression of EMMPRIN on monocytes markedly increased compared with patiens with SAP and heathy control group. Furthermore, increased level of IL-18 was positively associated with elevated expression of EMMPRIN on monocytes in AMI group （r2＝0.57, P<0.001）. The data proved that expression of EMMPRIN was enhanced in monocytes cultured in presence of IL-18 （P<0.05）. Conclusion IL-18 stimulates monocytes to express EMMPRIN, which may induce secretion of MMP-9, contributing to atherosclerotic plaque instability and rupture.

Abstract:AimTo investigate the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) and urokinase-type plasminogen activator(uPA) in aortic atherosclerotic plaques of apolipoprotein E knockout(ApoE-/-) mice and to explore the relationship between the two.MethodsApoE-/- mice were randomized into ordinary diet fed group and high-fat diet fed group，raising for 18 weeks.At 6 weeks, 10 weeks, 14 weeks, 18 weeks mice were sacrificed and observed by HE staining of atherosclerotic plaque morphology.EMMPRIN and uPA expression in aortic atherosclerotic plaques were detected by semi-quantity RT-PCR and Western blot.RusultsAtherosclerosis model was successfully established; EMMPRIN and uPA in aorta atherosclerotic plaques were highly expressed, with statistically significant difference from normal diet group (p<0.05).Expression of EMMPRIN and uPA increased with feeding time extended.ConclusionExpression of EMMPRIN and uPA in ApoE-/- mice aortic atherosclerosis increased with plaque lesions degree of severity, both of EMMPRIN and uPA may play a role in the atherosclerotic plaques development.

Abstract:Aim To evaluate the effect of AngiotensinⅡon EMMPRIN expression in THP-1 macrophage and its potential mechanism. Methods Macrophages cell line was esteblished by induced THP-1 using PMA,and then the effect of AngⅡ on EMMPRIN expression on THP-1 macrophages was investigated. Results RT-PCR and Western Blot showed that AngⅡ upregulated EMMPRIN expression in a dose and time dependent manner.Either nuclear factor-κB inhibitor PDTC or P65 RNAi treatment can suppress the effect of angⅡon EMMPRIN. Conclusion AngⅡupregulates the expression of EMMPRIN.Nuclear factor-κB is the critical factor involving in the EMMPRIN upregulation induced by angⅡ.

Abstract:Aim To investigate the changes of matrix metalloproteinase-2 and 9(MMP-2,MMP-9)in rat cardiac hypertrophy,and the effects of Pentoxifylline(PTX)on it in a rat model.Methods Twenty-four male SD rats were randomly divided into control group,norepinephrine(model)group and norepinephrine + PTX(treated)group.The rat cardiac hypertrophy models were established by intraperitoneal injection of norepinephrine(NE)twice a day for 15 days.Extracellular matrix remodeling was evaluated by morphological examination,stained with Van-Gieson(VG).The content of hydroxyproline in the tissue of myocardium was measured.The protein expression of MMP-2 and MMP-9 were examined by immunohistochemical analysis.Results NE-induced hypertrophy and extracellular matrix remodeling predominantly occurred in the left ventricular,the expression of the collagen(1.929±0.514 mg/g vs 1.009±0.442 mg/g,p<0.01)elevated obviously;the average of the grave scale of protein expression of the MMP-2(131.1±9.8)and MMP-9(125.3±4.1)were lower than those of the control group obviously(p<0.01);After PTX treatment,the collagen(1.151±0.215 mg/g)was decreased and the average of the grave scale of protein expression of MMP-2(153.5±6.9)and MMP-9(149.5±5.3)were higher than those of the model group prominently(p<0.01).Conclusion Pentoxifylline can prevent the cardiac hypertrophy and extracellular matrix remodeling,which was associated with the attenuation of myocardial MMP-2 and MMP-9.

Abstract:Aim To investigate the special pharmacological effect of phenytoin on the healing process after ballon injury in rat carotid artery.Methods Study was performed on rat model of balloon-injury in common carotid artery.Rats survived from successful operation were divided into phenytoin group and injury group.On the 28th day after operation,rats were anesthetized,then the left carotids and the corresponding part of the right carotids were separated,embedded with paraffin,sectioned into 5 μm and stained.Results On the 28th day after operation,the intima area(0.154±0.018 mm2 vs 0.204±0.054 mm2,p<0.01),intima/media area(1.70±0.08 vs 2.26±0.46,p<0.01)and the rate of restenosis(59.5%±3.2% vs 75.9%±13.3%,p<0.01)in phenytoin group were all less than those in injury group,while lumen area(0.106±0.024 mm2 vs 0.063±0.034 mm2,p<0.01)was larger than that in injury group,cell density in intima(72.18±20.08/cm2 vs 84.85±10.77/cm2,p<0.05),proliferating cell nuclear antigen(PCNA)positive cell counting(9.89±7.63 per 200 magnification vs 23.03±13.95 per 200 magnification,p<0.01)and α-smooth muscle actin positive cell counting(30.91±20.05 per 200 magnification vs 61.81±16.57 per 200 magnification,p<0.01)were all smaller than those in injury group;under polarized light,collagen could be visualized deposite in intima,but there were no statistic difference in collagen area and density(p>0.05).Conclusion 28 days after vascular injury,phenytoin can decrease the cell number in neointima and promote the synthesis of extracellular matrix which result in diminished neointima thickening.