Sca-1-Positive Cardiac Stem Cell migration in a Cardiac Infarction Model

Adult myocardium has the capacity for repair and regeneration, which is derived from cardiac stem cells (CSCs). In this study, we assessed the migration and changes in numbers of Sca-1-positive CSCs after myocardial infarction (MI) in vivo and in vitro. In this study, we showed that in a rat MI model the CSCs emerged around the vessels near the peri-infarct zone and in the epicardium of the infarcted area. Four weeks after infarction, no differences in the expression of connexin 43 (Cx43) were observed in the peri-infarct and infarct zones. In vitro, we mimicked tissue ischemia and hypoxia by using a culture environment of 5 % O₂ and a wound healing assay to monitor the migration of CSCs. In conclusion, under hypoxic conditions, the CSCs, conveyed by blood vessels, migrated from the niche to the infarct zone for repairing the damaged myocytes. The number of endogenous migrating CSCs was proportionate to the repair time after infarction, rather than the degree of infarction. Four weeks after MI, the expression of Cx43 was not altered in migratory CSCs, namely no enhanced gap-junctional communication with cardiomyocytes was seen in the CSCs. Further studies are necessary to delineate the molecular mechanisms that drive the migration of CSCs after MI.     

塞来昔布对心肌梗死后心肌细胞凋亡的影响

 目的：研究选择性环氧化酶-2抑制剂塞来昔布(celecoxib,Cele)对心肌梗死后心肌细胞抗氧化损伤能力、Bcl-2、Bax蛋白表达及细胞凋亡的影响。方法：选择新西兰兔24只，随机分为3组（每组8只）：假手术组（sham组）、心肌梗死组（MI组）、塞来昔布组(Cele组，10 mg·kg^-1·d^-1,灌胃)。6周后取梗死灶边缘缺血心肌制作组织匀浆进行NO浓度(以NO^-₂/ NO^-₃间接表示)、结构型一氧化氮合酶(cNOS)和诱导型一氧化氮合酶(iNOS)活性及总抗氧化能力（T-AOC）测定，并做病理观察，免疫组化观察各组Bcl-2、Bax蛋白表达，TUNEL法比较其细胞凋亡程度。结果：MI组心肌间质水肿，较多心肌纤维化与炎性细胞浸润,心肌胞浆空泡样变，心肌肌原纤维间隙增宽，排列紊乱，可见局灶性肌丝溶解，肌浆网明显扩张。而Cele组病理改变较轻。Cele组心肌组织匀浆中NO^-₂/ NO^-₃浓度、iNOS活性低于MI组，cNOS活性及T-AOC高于MI组(P<0.05)； Cele组Bcl-2表达阳性率高于MI组而bax表达率低于MI组（P<0.01）；细胞凋亡程度低于MI组（P<0.01）。结论：塞来昔布可增强心肌梗死后心肌细胞抗氧化损伤能力并降低细胞凋亡率。     

Myocardial apoptosis associated with the expression of proinflammatory cytokines during the course of myocardial infarction.

To clarify the role of myocardial apoptosis associated with the expression of proinflammatory cytokines in human myocardial infarction (MI), we have analyzed the expression of apoptosis positive for single-stranded DNA (ss-DNA) antibody, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-8 in 147 samples of infarcted myocardial tissue from 65 patients. ss-DNA-positive apoptotic nuclei were found mainly in cardiomyocytes in the border zones and granulation tissue cells in the infarct foci. The ss-DNA index (SI) of cardiomyocytes (average 0.13%) peaked at stage II (established myocardial necrosis), the value being significantly higher than at stages III (macrophage infiltration), IV (granulation formation), and V (scar formation) (P<0.05), whereas the SI of granulation tissue (average 0.08%) at stages III, IV, and V showed no significant differences between the three stages. These results suggest that cardiomyocyte apoptosis in the border zone is responsible for cellular loss in the acute stage of MI, whereas granulation tissue apoptosis may not be involved in the process of ventricular remodeling. TNF-alpha was expressed in cardiomyocytes in the border zones of infarct foci, but no significant positive correlation was found between SI and TNF-alpha index in cardiomyocytes (r=0.08, P = 0.37), suggesting that TNF-alpha does not serve as a direct trigger of cardiomyocyte apoptosis in vivo. The number of IL-8-positive cells peaked at stage II, and IL-8-myeloperoxidase-double-positive neutrophils were frequently detected, indicating that infiltrating neutrophils are the predominant source of IL-8 in the infarcted myocardium. These results suggest that, in human MI, TNF-alpha produced by cardiomyocytes does not play a critical role in their apoptosis, and that IL-8 produced by neutrophils is responsible for the subsequent accumulation and activation of neutrophils, thus increasing the degree of myocardial damage.     

Co-deposition of clusterin with the complement membrane attack complex in myocardial infarction.

Clusterin is a multi-functional plasma glycoprotein that has been shown to inhibit formation of the complement membrane attack complex (MAC) by preventing the association of terminal complement complexes with target cell membranes. Recent studies have suggested that complement activation is involved in the development of tissue injury of myocardial infarction. In this study we observed that clusterin is selectively deposited in the infarcted areas of human myocardium. Clusterin deposits were observed in the heart tissue of 10 patients whose infarcted lesions were 8 hr to 14 days old, but not in patients who died from other causes. Clusterin co-localized with the MAC on the surface of damaged cardiomyocytes. In normal myocardium only endothelial lining of blood vessels occasionally stained positive for clusterin. The 80,000 MW clusterin was also detected by Western blot analysis in extracts of myocardial infarction lesions, but only faintly in extracts of normal heart. As clusterin has apparently failed in protecting myocardium against complement-mediated cell injury its main role might be to participate in the clearance of damaged and necrotic tissue together with the MAC.     

黄芩素通过抗氧化及调节细胞内钙离子浓度抑制大鼠缺氧/复氧诱导的心肌细胞凋亡

背景：黄芩素对缺氧复氧损伤的心血管有保护作,但机制至今不清。 目的：探讨中药黄芩素对心肌细胞缺氧/复氧损伤导致心肌细胞凋亡的保护作用机制。 方法：体外培养大鼠乳鼠心肌细胞培养。实验分3组：正常对照组为正常培养的心肌细胞未做处理;缺氧/复氧组为应用缺氧/复氧方法诱导心肌细胞凋亡损伤;黄芩素预处理组为经黄芩素预处理30 min后经缺氧/复氧诱导的心肌细胞。通过检测培养基上清液中乳酸脱氢酶活力检测细胞损伤程度及黄芩苷保护作用;应用原位末端标记细胞法标记细胞后,流式细胞检测心肌细胞凋亡率;应用免疫印迹方法检测心肌细胞凋亡蛋白Bax与抗凋亡蛋白Bcl-2的蛋白表达水平;应用Fura-2-AM负载心肌细胞,实时检测心肌细胞内Ca2+浓度变化。 结果与结论：与正常对照组相比,缺氧/复氧组上清液乳酸脱氢酶活性、心肌细胞凋亡率、Bax蛋白含量、心肌细胞Ca2+浓度均增加(P < 0.05),Bcl-2蛋白含量降低(P < 0.05)。与缺氧/复氧组相比,黄芩素预处理组乳酸脱氢酶含量、心肌细胞凋亡率、Bax蛋白含量及心肌细胞Ca2+浓度均降低(P < 0.05),Bcl-2蛋白含量增加(P < 0.05)。证实黄芩素能抑制缺氧/复氧导致的心肌细胞凋亡,其作用机制可能与抗氧化与调节心肌细胞内钙离子浓度有关     

Sequential changes in localization of repair-related proteins (heat shock protein 70, ubiquitin and vascular endothelial growth factor) in the different stages of myocardial infarction

AIMS: The myocardium expresses vascular endothelial growth factor (VEGF), heat shock protein 70 (HSP70), and ubiquitin immediately after the onset of cardiac ischaemia. This study demonstrated the sequential changes in localization of these proteins, in addition to fibronectin and troponin T (TnT), in human hearts with myocardial infarction (MI). METHODS AND RESULTS: Myocardial tissues from 40 autopsied MI cases were immunostained with the five antibodies against VEGF, HSP70, ubiquitin, fibronectin and TnT. Fibronectin was recognized only in the cardiomyocytes with infarction. Although TnT, HSP70, ubiquitin and VEGF were detected in the affected myocardium in the early stages, their expression in cardiomyocytes around infarcted foci were more intense. The cardiomyocytes with coagulative myocytolysis were positive for fibronectin, but negative or weakly positive for TnT, HSP70, ubiquitin and VEGF. In contrast, the cardiomyocytes with colliquative myocytolysis were strongly positive for TnT, HSP70, ubiquitin and VEGF, but negative for fibronectin. CONCLUSIONS: Immunostaining using antibodies to fibronectin, TnT, HSP70, ubiquitin and VEGF is useful for the discrimination between infarcted myocytes and ischaemia-damaged myocytes in the human heart with MI at autopsy.     

The "border zone" in myocardial infarction. An ultrastructural study in the dog using an electron-dense blood flow marker

There is controversy over the existence of a lateral "border zone" of intermediately injured tissue in the developing myocardial infarct (MI). The authors attempted an ultrastructural demonstration of this zone in serial subepicardial biopsies from developing MIs in dogs subjected to 90 minutes, 6 hours, or 24 hours of left anterior descending coronary artery ligation (4 dogs per group). After ligation, 400,000 units of horseradish peroxidase was infused through the left atrial appendage as a blood flow marker, to allow distinction of perfused and ischemic myocytes under electron microscopy. Evans blue stain was infused in the same way for gross guidance in harvesting biopsies across the lateral margins of the ischemic region. Interdigitation of perfused and ischemic tissue was observed over a lateral margin 6 mm wide, which caused admixture of perfused and ischemic myocytes in biopsies from this region. Ultrastructural ischemic injury was graded on a five-level qualitative scale (normal, mild, moderate, severe, lethal). Perfused myocytes from control and border sites were equivalently well preserved (79% normal, 21% mild injury, n = 353). Ischemic myocyte injury increased with duration of ischemia. At 90 minutes, 65% of ischemic myocytes had mild injury, 35% moderate (n = 138); at 6 hours, 17% of ischemic myocytes had moderate injury, 81% severe, 2% lethal (n = 115); at 24 hr, 100% of ischemic myocytes had lethal injury (n = 148). Severity of ischemic myocyte injury did not vary from the lateral border to the center of the ischemic region: there was no lateral "border zone." However, if myocytes were not separated into perfused and ischemic subpopulations before statistical comparison of biopsy site to severity of injury, false evidence of a "border zone" was obtained.     

Cardiac and skeletal myopathy in Fabry disease: a clinicopathologic correlative study

Skeletal muscle disturbances are commonly reported in patients with Fabry disease. Whether they derive from cardiac dysfunction or direct muscle involvement is still unclear. Clinical, noninvasive, and invasive cardiac and muscle studies, including an endomyocardial and muscle biopsy, were obtained in 12 patients (mean age, 42.1 ± 12.6 years; range, 24-58 years) with Fabry disease. In the youngest patients (group A, 4 men aged <35 years), results of cardiac and skeletal noninvasive studies were normal, except for reduced velocities in tissue Doppler imaging. Histologic examination indicated that muscle myocytes were unaffected, whereas muscle vessels showed the presence of mild glycosphingolipid accumulation in endothelial and smooth muscle cells. In the heart, cardiomyocytes and endothelial and smooth muscle cells of intramural cardiac vessels were involved by the disease. The oldest patients (group B, 6 men and 2 women aged >35 years) showed ultrasound muscle disarray and electromyography signs of myopathy, increased left ventricular mass, and normal cardiac function. Histologic examination showed that muscle myocytes contained mild glycosphingolipid accumulation compared with severe engulfment of cardiomyocytes. Moreover, similar infiltration of myocardial and muscle intramural vessels, causing lumen narrowing and fibrofatty tissue replacement, was observed. Direct muscle involvement occurs in patients with Fabry disease. It is milder and delayed compared with that in the heart. The difference in organ function and the need of residual α-galactosidase A activity are the likely causes.     

Expression of cyclooxygenase-1 and cyclooxygenase-2 in the normal human heart and in myocardial infarction.

INTRODUCTION: Cyclooxygenase is a key enzyme in prostanoid synthesis. It exists in two isoforms: cyclooxygenase-1 (COX-1), which is constitutively expressed in cells and tissues maintaining normal homeostasis, and cyclooxygenase-2 (COX-2), which is normally not present in most cells, but can be induced by various stimuli. Little is known about the significance of COX isoforms in the normal human heart and in myocardial infarction (MI). Thus, we aimed to investigate the immunohistochemical expression of COX-1 and COX-2 in the normal human heart and in MI. METHODS: Our study included autopsy samples of heart tissue from 15 healthy individuals who died in accidents, and from 40 patients with MI who died few hours to a month after the onset of symptoms. Immunohistochemistry was performed by a sensitive peroxidase-streptavidin method on formalin fixed, paraffin-embedded tissue, using monoclonal antibodies against COX-1 and COX-2. RESULTS: In normal hearts, COX-1 was found in endothelial and smooth muscle cells of blood vessels and in endothelial cells of the endocardium. In MI, it was expressed in inflammatory cells, as well as in myofibroblasts and capillaries of granulation and fibrous tissue. COX-2 was either not present or it was present in occasional myocytes in the normal hearts. In MI, its expression was induced in cardiomyocytes as well as in interstitial inflammatory cells, and in capillaries and myofibroblasts in granulation tissue. CONCLUSIONS: Our results suggest that COX-1 is associated with normal homeostasis in the heart, whereas COX-2 probably mediates inflammatory reaction in MI. It appears that both COX-1 and COX-2 are associated with the healing processes and scar formation after MI.     

Intracoronary delivery of DNAzymes targeting human EGR-1 reduces infarct size following myocardial ischaemia reperfusion

Despite improvements in treatment, myocardial infarction (MI) remains an important cause of morbidity and mortality. Inflammation arising from ischaemic and reperfusion injury is a key mechanism which underpins myocardial damage and impairment of cardiac function. Early growth response-1 (Egr-1) is an early immediate gene and a master regulator that has been implicated in the pathogenesis of ischaemia-reperfusion (IR) injury. This study sought to examine the effect of selective inhibition of Egr-1 using catalytic deoxyribonucleic acid molecules (DNAzymes, DZs) delivered via the clinically relevant coronary route in a large animal model of myocardial IR. It was hypothesized that Egr-1 inhibition with intracoronary DZ would reduce infarction size by modulating its downstream effector molecules. Egr-1 DZs inhibited the adherence of THP-1 monocytes to IL-1β-activated endothelial cells in vitro and retained its catalytic activity up to 225 min after in vivo administration. In a porcine model of myocardial IR (45 min ischaemia/3 h reperfusion), DZ was taken up in the cytoplasm and nuclei of cardiomyocytes and endothelial cells in the myocardium after intracoronary delivery. Egr-1 DZs reduced infarct size and improved cardiac functional recovery following intracoronary delivery at the initiation of IR in this large animal model of MI. This was associated with inhibition of pro-inflammatory Egr-1 and ICAM-1 expression, and the reduced expression of TNF-α, PAI-1, TF, and myocardial MPO activity in tissue derived from the border zone of the infarct. Taken together, these data suggest that strategies targeting Egr-1 via the intracoronary route after IR injury in pigs have potential therapeutic implications in human MI.     

The mechanical coupling of adult marrow stromal stem cells during cardiac regeneration assessed in a 2-D co-culture model

Postnatal cardiomyocytes undergo terminal differentiation and a restricted number of human cardiomyocytes retain the ability to divide and regenerate in response to ischemic injury. However, whether these neo-cardiomyocytes are derived from endogenous population of resident cardiac stem cells or from the exogenous double assurance population of resident bone marrow-derived stem cells that populate the damaged myocardium is unresolved and under intense investigation. The vital challenge is to ameliorate and/or regenerate the damaged myocardium. This can be achieved by stimulating proliferation of native quiescent cardiomyocytes and/or cardiac stem cell, or by recruiting exogenous autologous or allogeneic cells such as fetal or embryonic cardiomyocyte progenitors or bone marrow-derived stromal stem cells. The prerequisites are that these neo-cardiomyocytes must have the ability to integrate well within the native myocardium and must exhibit functional synchronization. Adult bone marrow stromal cells (BMSCs) have been shown to differentiate into cardiomyocyte-like cells both in vitro and in vivo. As a result, BMSCs may potentially play an essential role in cardiac repair and regeneration, but this concept requires further validation. In this report, we have provided compelling evidence that functioning cardiac tissue can be generated by the interaction of multipotent BMSCs with embryonic cardiac myocytes (ECMs) in two-dimensional (2-D) co-cultures. The differentiating BMSCs were induced to undergo cardiomyogenic differentiation pathway and were able to express unequivocal electromechanical coupling and functional synchronization with ECMs. Our 2-D co-culture system provides a useful in vitro model to elucidate various molecular mechanisms underpinning the integration and orderly maturation and differentiation of BMSCs into neo-cardiomyocytes during myocardial repair and regeneration.     

Time-Dependent Expression Patterns of Cardiac Aquaporins Following Myocardial Infarction

Aquaporins (AQPs) are expressed in myocardium and the implication of AQPs in myocardial water balance has been suggested. We investigated the expression patterns of AQP subtypes in normal myocardium and their changes in the process of edema formation and cardiac dysfunction following myocardial infarction (MI). Immunostaining demonstrated abundant expression of AQP1, AQP4, and AQP6 in normal mouse heart; AQP1 in blood vessels and cardiac myocytes, AQP4 exclusively on the intercalated discs between cardiac myocytes and AQP6 inside the myocytes. However, neither AQP7 nor AQP9 proteins were expressed in CD1 mouse myocardium. Echocardiography revealed that cardiac function was reduced at 1 week and recovered at 4 weeks after MI, whereas myocardial water content determined by wet-to-dry weight ratio increased at 1 week and rather reduced below the normal at 4 weeks. The expression of cardiac AQPs was up-regulated in MI-induced groups compared with sham-operated control group, but their time-dependent patterns were different. The time course of AQP4 expression coincided with that of myocardial edema and cardiac dysfunction following MI. However, expression of both AQP1 and AQP6 increased persistently up to 4 weeks. Our findings suggest a different role for cardiac AQPs in the formation and reabsorption of myocardial edema after MI.     

An immunohistochemical study of feline myocardial fibrosis

The aim of the present study was to investigate the pathology of feline myocardial fibrosis. The hearts from 40 cats with myocardial fibrosis were compared with the hearts from 25 normal cats. Clinical data were available in 11 cases. Hearts with myocardial fibrosis were hypomotile and there were hyperechoic areas in the ventricular wall on echocardiography. The presence of myocardial fibrosis was correlated significantly with hypertrophy of the ventricles, atrial dilation and angiosclerosis. Immunohistochemical studies demonstrated that normal feline cardiomyocytes expressed matrix metalloproteinase (MMP)-2, MMP-9, MMP-14, tissue inhibitor of matrix metalloproteinase (TIMP)-2 and transforming growth factor (TGF)-β2. Fibroblasts in normal hearts expressed only TIMP-2. In the hearts with myocardial fibrosis, expression of MMP-2, TIMP-3 and TGF-β2 by cardiomyocytes was significantly increased, but TIMP-2 expression was diminished. Fibroblasts in the affected hearts showed expression of MMP-14 in several cases. These findings suggest that a complex fibrotic remodelling of the feline myocardium occurs in this disease and that cardiomyocytes are involved in this process.     

Anti-inflammatory Effect of Protocatechuic Aldehyde on Myocardial Ischemia/Reperfusion Injury In Vivo and In Vitro

Myocardial ischemia/reperfusion (MI/R) injury, in which inflammatory response plays a vital role, is frequently encountered in clinical practice. The present study was aimed to investigate the anti-inflammatory effect and the possible mechanism of protocatechuic aldehyde (PAl) on MI/R injury both in vivo and in vitro. The rat model of MI/R injury was induced by ligation of the left anterior descending coronary artery for 30 min, followed by 3-h reperfusion, and pretreatment with PAl could protect the heart from MI/R injury by reducing myocardial infarct size and the activities of creatine kinase-MB and cardiac troponin I (cTn-I) in serum. Also, PAl administration markedly reduced cellular injury induced by simulated ischemia/reperfusion (SI/R) in cultured neonatal rat cardiomyocytes, which was evidenced by increased cell viability, reduced lactate dehydrogenase and cTn-I activities in the culture medium, and greatly decreased percentage of cell apoptosis. Moreover, the levels of tumor necrosis factor-α, interleukin-6, intracellular adhesion molecule-1, phosphorylated IκB-α, and the nuclear translocation of nuclear factor-kappa B (NF-κB) were all evidently decreased by PAl both in vivo and in vitro. Taken together, these observations suggested that PAl could exert great protective effects against MI/R injury in rats and SI/R injury in cultured neonatal rat cardiomyocytes, and the cardioprotective mechanism might be involved in the suppression of inflammatory response via inhibiting the NF-κB signaling pathway.     

MicroRNA-23a is involved in tumor necrosis factor-α induced apoptosis in mesenchymal stem cells and myocardial infarction

Cell therapy has emerged as an attractive therapeutic modality to treat myocardial infarction (MI) via repairing damaged myocardium, and mesenchymal stem cells (MSCs) are an appealing therapeutic approach for cardiac regeneration. However, the clinical application of MSC-based therapy is restricted because of the poor survival of implanted cells, and this poor survival remains poorly understood. Using a tumor necrosis factor (TNF)-α-induced bone marrow (BM)-MSC injury model in vitro and a rat MI model in vivo, we showed in the current study that miR-23a was involved in TNF-α-induced BM-MSC apoptosis through regulating caspase-7 and that the injection of BM-MSCs overexpressing miR-23a could improve left ventricular (LV) function and reduce infarct size in the rat MI model. Our findings elucidate the etiology of MI and provide an alternative treatment strategy for patients with heart failure caused by MI who are not optimal candidates for surgical treatment.     

Effect of decay-accelerating factor on the assembly of the classical and alternative pathway C3 convertases in the presence of C4 or C3 nephritic factor

Decay-accelerating factor (DAF) is a 70,000 MW membrane protein that regulates the complement system on the cell surface. In the present study, we found that DAF had no effect on the classical pathway C3 and C5 convertases that had been stabilized by C4 nephritic factor (C4NeF). In DAF-incorporated cells, however, the assembly of the classical pathway C3 convertase was markedly inhibited even in the presence of C4NeF. C3 nephritic factor (C3NeF) in the alternative pathway protected the C3 convertase from the action of DAF to some extent, while the generation of C3 convertase was also inhibited by DAF. These results indicate that under physiological conditions, DAF functions to inhibit the assembly of C3 convertases even in the presence of nephritic factors, although it has no or little effect on the stabilized convertases. Thus, it is likely that DAF plays an important role in protection of host cells from damage by autologous complement in patients with nephritic factors.     

Evaluation of the membrane attack complex of complement for the detection of a recent myocardial infarction in man

The diagnosis of an acute myocardial infarction (MI) can be cumbersome for pathologists. Even with a positive nitroblue tetrazolium (NBT) reaction, haematoxylin and eosin (H&E) evaluation of the myocardial tissue can remain inconclusive. Early signs presumed diagnostic for myocardial infarction, such as hypereosinophilia, waviness, and contraction band necrosis, have to be considered non-specific and are probably reversible signs of ischaemia. Several studies implicate the complement system, and especially complement factor C9, as part of the membrane attack factor (MAC), in cardiomyocyte damage during MI. In a post-mortem study on well-documented cardiological autopsies, we evaluated the use of complement factor C9 immunostaining as a marker for the detection of very recent MI. Forty-three tissue samples from 40 patients were obtained from the left ventricular free wall only, a region that can be specifically attributed to one corresponding coronary artery. As some patients presented with MIs of various stages in that perfusion area, in total 57 observations were possible. C9 immunostaining specifically detected irreversibly damaged (=infarcted) cardiomyocytes, as is implied by the lytic activity of C9/MAC binding to cell membranes. Most interesting was the group of clinically suspected, NBT-positive MIs resulting from very recent myocardial ischaemia. In this population, where H&E evaluation by (cardio-) experienced pathologists was not conclusive, C9 immunostaining clearly pointed towards myocardial infarction in 47% of the cases. In conclusion, C9 immunostaining, routinely practicable in the pathology laboratory, has an additional value in discriminating between reversible ischaemia and infarcted cardiomyocytes in very early MIs.     

Induction of a reversible cardiac lipidosis by a dietary long-chain fatty acid (erucic acid). Relationship to lipid accumulation in border zones of myocardial infarcts.

Previous studies have demonstrated that cardiac myocytes in the border zone of acute myocardial infarction become markedly overloaded with neutral lipid during the transition from reversible to irreversible injury. To examine directly the role of these changes in neutral lipid metabolism in the development of irreversible cellular injury and associated increases in tissue Ca2+ content, the authors fed rats large amounts of a fatty acid (erucic acid) that is poorly oxidized by the heart and that subsequently accumulates as neutral lipid. Rats fed a high erucic acid (C22:1) diet in the form of 20% rapeseed oil for 3-5 days had a fourfold increase in triglyceride (49.5 +/- 3.8 SEM mg/g wet wt versus 13.6 +/- 13, n = 4) and a 60% increase in long-chain acyl CoA content (166.0 +/- 21.9 versus 91.5 +/- 9.0 nM/g wet wt, n = 4), compared with controls. However, there was no change in long-chain acyl carnitine or total phospholipid content. Histochemical studies showed accumulation of numerous lipid droplets in the myocytes, and electron microscopy revealed localization of lipid vesicles in direct contact with mitochondria, thus mimicking the lipid-laden cells in the border zone regions of acute myocardial infarcts. The acute lipidosis was reversible with either continued feeding of erucic acid for several weeks or conversion to a normal diet. It was not associated with an increased tissue Ca2+ content, nor with cell necrosis. However, continued erucic acid intake for 3 months was associated with focal myocardial degeneration and loss of myocytes. These results suggest that acute increases in neutral lipids, as found in the border zone of acute myocardial infarction, may not be the cause of progression to irreversible damage during acute myocardial injury, but that the persistent presence of similar lipid material over months may result in focal myocardial degeneration.     

A novel Danshensu/tetramethylpyrazine protects against Myocardial Ischemia Reperfusion Injury in rats

A new Danshensu/tetramethylpyrazine derivative (ADTM) with cardio-protection effects such as antioxidant, arterial relaxation, pro-angiogenesis and antiplatelet activities. Platelet activating factor receptor (PAFR) plays a key role in myocardial ischemia reperfusion (MIR) injury. This study aims to investigate the protective role of ADTM in MIR injury and clarify the potential role of PAFR. We measured the effects of ADTM on MIR injury in rats in vivo and hypoxia re-oxygenation (HR) injury in neonatal rat ventricular myocytes (NRVMs) in vitro. The results show that ADTM can significantly improve the IR-induced decline in heart function as increasing EF and FS, and restore the decreased cardiac hemodynamic parameters (LVSP, ± dp/dt max) and increased the level of LVEDP, decrease the infarct size of damaged myocardium and lactate dehydrogenase (LDH) activity in serum. Additionally, ADTM inhibits cardiomyocytes apoptosis, caspase-3 activity, and inflammatory response as well as down-regulates the MIR-induced IL-1β and TNFα production. Next, PAFR expression was significantly down-regulated in cardiomyocytes of MIR model in vivo and in vitro after treated with ADTM compare to IR group. At the same time, ADTM and PAFR small interfering RNA (siRNA) could inhibit cardiomyocytes apoptosis and inflammation during HR, while PAF presents the opposite effect. Furthermore, the above effects of PAF in HR induced cardiomyocytes were reversed by co-treatment of ADTM. Our findings demonstrate for the first time that ADTM protects against MIR injury through inhibition of PAFR signaling, which provides a new treatment for MIR.     

Changes in cardiovascular function on treatment of inhibitors of apoptotic signal transduction pathways in left ventricular remodeling after myocardial infarction.

INTRODUCTION: It has been suggested that apoptosis in cardiac remodeling after myocardial infarction (MI) occurs in cardiomyocytes and is critically involved in the process of postinfarct cardiac remodeling. We investigated the pathophysiological link between myocardial apoptosis and cardiovascular function by modulating apoptotic signal transduction pathways. METHODS: Either a caspase-3 inhibitor (CasI) or a calpain inhibitor (CalI) was administered immediately after MI in a rat model of MI. Blood pressure (BP), heart rate (HR), and blood flow velocity (BFV) were measured, and pressure-rate product (PRP) was calculated to estimate the changes in cardiovascular function (n=6 for each group). RESULTS: BFV showed no remarkable changes in any of the groups. Both systolic blood pressure (SBP) and HR changed significantly (P<.01) in the MI+CasI and MI+CalI groups at 1 day after MI and returned to control levels thereafter. In contrast, SBP and HR remained significantly (P<.01) altered in the MI group. PRP in the MI groups was significantly decreased (P<.05 in the MI and MI+CasI groups; P<.01 in the MI+CalI group) at 1 day after MI and returned to control levels at 4 days. CONCLUSION: This study suggests that inhibition of apoptosis during left ventricular remodeling ameliorates cardiovascular function in remodeled hearts.