Survival and development of neonatal rat cardiomyocytes transplanted into adult myocardium

Transplantation of neonatal cardiomyocytes is a novel approach for the treatment of heart failure and myocardial infarction, but quantitative information on long-term cell survival and development is limited. Male donor cardiomyocytes were isolated from neonatal Fischer 344 rats (1-2 days), purified, and injected into the left ventricular wall of female syngeneic adult rats. One hour to 12 weeks later, genomic DNA was isolated from recipient hearts. The amount of male DNA per sample was determined by quantitative real-time TaqMan PCR of the male-specific Sry gene. Transplanted cell survival was 57 +/- 9% at 0-1 h, 24 +/- 6% at 24 h, 28 +/- 11% at 7 days, 27 +/- 3% at 14 days, 23 +/- 8% at 4 weeks and 15 +/- 3% at 12 weeks. The caspase inhibitor AcYVADcmk failed to improve transplanted cell survival at 24 h, suggesting that apoptosis did not play a major role in cell loss. Histology revealed that transplanted cells became more elongated over time, developed cross-striations, and that their nuclei increased in size. However, at 12 weeks, transplanted cells and their nuclei were still smaller than those of host myocardium. We established a quantitative survival profile for neonatal cardiomyocytes transplanted into normal adult myocardium. There was significant loss of cells within 24 h, but 15% of transplanted cells survived 12 weeks. Those cells that did survive underwent differentiation and developed visible sarcomeres, suggesting a potential contribution toward ventricular function.     

Inhibition of K+ currents by homocysteine in rat ventricular myocytes

INTRODUCTION: Clinical evidence suggests that increased blood levels of homocysteine may be an independent risk factor for the development of cardiovascular disease, but the functional effects of this sulfhydryl amino acid on the myocardium are poorly understood. The present study was conducted to determine the direct effects of homocysteine on the electrophysiologic properties of the heart. METHODS AND RESULTS: Whole-cell voltage-clamp recordings were made in ventricular myocytes isolated from normal rat hearts to analyze the Ca2+-independent, transient outward K+ current (I(to)), a major repolarizing current in these cells. Maximum I(to) density (measured at +60 mV) was decreased approximately 47% from baseline in the presence of 500 microM homocysteine (P < 0.05), but the amount of block varied in a frequency- and voltage-dependent manner. Decreased I(to) density was not accompanied by significant changes in voltage- or time-dependent properties of the current, nor was it affected by pretreating myocytes with the protein kinase inhibitor staurosporine. Because a portion of total extracellular homocysteine is oxidized, we examined the response to homocystine, the oxidized form of homocysteine. In myocytes superfused with 500 microM homocystine, maximum I(to) density was decreased by approximately 40% from baseline (P < 0.05). In contrast, the thiolactone form of homocysteine did not alter I(to) amplitude. CONCLUSION: These data suggest that homocysteine and its oxidized form homocystine acutely inhibit I(to) channels in ventricular myocytes by mechanisms involving the free thiol or disulfide moieties of these compounds. High homocysteine or homocystine levels may contribute to abnormal repolarization and arrhythmogenic conditions in the intact heart.     

Prospective isolation of human embryonic stem cell-derived cardiovascular progenitors that integrate into human fetal heart tissue

A goal of regenerative medicine is to identify cardiovascular progenitors from human ES cells (hESCs) that can functionally integrate into the human heart. Previous studies to evaluate the developmental potential of candidate hESC-derived progenitors have delivered these cells into murine and porcine cardiac tissue, with inconclusive evidence regarding the capacity of these human cells to physiologically engraft in xenotransplantation assays. Further, the potential of hESC-derived cardiovascular lineage cells to functionally couple to human myocardium remains untested and unknown. Here, we have prospectively identified a population of hESC-derived ROR2⁺/CD13⁺/KDR⁺/PDGFRα⁺ cells that give rise to cardiomyocytes, endothelial cells, and vascular smooth muscle cells in vitro at a clonal level. We observed rare clusters of ROR2⁺ cells and diffuse expression of KDR and PDGFRα in first-trimester human fetal hearts. We then developed an in vivo transplantation model by transplanting second-trimester human fetal heart tissues s.c. into the ear pinna of a SCID mouse. ROR2⁺/CD13⁺/KDR⁺/PDGFRα⁺ cells were delivered into these functioning fetal heart tissues: in contrast to traditional murine heart models for cell transplantation, we show structural and functional integration of hESC-derived cardiovascular progenitors into human heart.     

淫羊藿苷预适应对乳鼠心肌细胞的保护作用

目的:探讨淫羊藿苷预适应对培养乳鼠心肌细胞缺氧/复氧损伤和氧化损伤的作用及其机制。方法:体外培养原代乳鼠心肌细胞,淫羊藿苷预适应24h后,采用连二亚硫酸钠(Na2S2O4)诱导心肌细胞缺氧/复氧损伤和过氧化氢(H2O2)诱导氧化损伤模型,测定细胞存活率(MTT法)、细胞培养液中乳酸脱氢酶(LDH)释放量、细胞内超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。结果:在缺氧/复氧损伤模型和氧化损伤模型中,淫羊藿苷预适应明显提高细胞存活率,增加胞内SOD活性,降低培养液中LDH释放量和胞内MDA含量。结论:淫羊藿苷预适应对缺氧/复氧损伤以及氧化损伤心肌细胞都具有明显的保护作用,可能与其抑制脂质过氧化作用有关。     

恩格列净及达格列净对棕榈酸诱导的心肌细胞损伤的保护作用及其机制

目的 探讨钠-葡萄糖共转运蛋白-2抑制剂恩格列净（empagliflozin,EMPA）及达格列净（dapagliflozin,DAPA）对棕榈酸（palmitic acid,PA）诱导H9c2心肌细胞损伤的保护作用及其可能机制。方法 采用PA诱导H9c2心肌细胞损伤,CCK-8法筛选PA、EMPA及DAPA的最佳给药浓度;Western blotting检测TLR4、p-AKT、p-mTOR、Nrf2和HO-1的蛋白表达水平;ELISA法检测IL-1β、IL-6和TNF-α的含量;荧光显微镜和流式细胞术检测PA诱导H9c2心肌细胞中ROS水平。结果 PA 100 μmol·L^–1刺激24 h可诱导H9c2心肌细胞存活率明显下降（P<0.01）,IL-1β、IL-6、TNF-α、TLR4蛋白表达、p-mTOR蛋白表达及ROS水平明显增加（P<0.01）,p-AKT、Nrf2和HO-1蛋白表达显著降低（P<0.01）;与模型组比较,经EMPA及DAPA处理后,细胞存活率明显增加（P<0.01）,IL-1β、IL-6、TNF-α、TLR4蛋白表达、p-mTOR蛋白表达及ROS水平明显降低（P<0.05或P<0.01）,p-AKT、Nrf2和HO-1蛋白表达显著上调（P<0.05或P<0.01）。结论 EMPA及DAPA对PA诱导的心肌细胞损伤均具有保护作用,其机制可能与下调TLR4、p-mTOR蛋白表达,增强AKT蛋白磷酸化,激活Nrf2/HO-1通路,抑制ROS的生成有关。     

苓桂术甘汤对慢性心律失常大鼠心肌损伤的保护作用及对Nrf2/HO-1通路的影响

[目的]探讨苓桂术甘汤对慢性心律失常大鼠心肌损伤的保护作用及对核因子E2相关因子2(nuclear factor E2 related factor 2,Nrf2)/血红素氧合酶-1(heme oxygenase-1,HO-1)通路的影响.[方法]45只雄性SD大鼠中随机选择10只作为正常对照组,其余35只经尾静脉注射...     

体外诱导脂肪来源细胞向心肌细胞分化的实验研究

目的通过5-氮杂胞苷(5-AZA)体外诱导脂肪来源细胞(adipose-derived cells,ADC),来观察其向心肌细胞分化的潜能,探讨脂肪来源细胞治疗缺血性心脏病的可能性。方法应用酶消化法获得兔ADC,并进行体外培养、扩增、鉴定。然后5-AZA体外诱导3周后,应用RT-PCR检测心肌细胞特异性α肌球蛋白重链(-αMHC)基因。结果RT-PCR显示与正常心肌组织-αMHC阳性条带对照,诱导后ADC也在相同位置出现-αMHC的阳性条带,而未诱导ADC没有阳性条带出现。结论ADC可在一定诱导条件下向心肌细胞分化,是一种较有潜力的治疗缺血性心脏病的移植细胞。     

眼睛蛇毒心脏毒素对大鼠心肌细胞收缩及细胞内钙离子的作用

目的 研究眼睛蛇毒心脏毒素（Cardiotoxin,CTX）对心肌细胞的形态、收缩幅度和细胞内钙离子（[Ca^2＋]i）的作用。方法 应用荧光计量法（以Fura-2／AM为荧光染料）及光学成像系统来测定单个心肌细胞[Ca^2＋]i和收缩幅度。结果 0．001～1μmol／L的CTX使心肌细胞由杆状变成圆形,药物的作用从第1分钟时开始,到第20分钟时趋于稳定。在电刺激存在的情况下,1μmol／L的CTX最初导致电诱导的[Ca^2＋]i和收缩幅度瞬间增加,接下来[Ca^2＋]i时程延长,最终细胞对电刺激不敏感、突然收缩、[Ca^2＋]i持续增高。在缺乏电刺激的情况下,1μmol／L的CTX可诱导Ca^2＋震荡波、持续性[Ca^2＋]i增高,这种作用与40mmol／L的KCl和10mmol／L咖啡因所引起的[Ca^2＋]i瞬间增加不同。结论 CTX作用初期使[Ca^2＋]i增高,使细胞[Ca^2＋]。超载,同时伴随细胞形状的改变。     

人参总皂甙对大鼠心肌细胞凋亡影响的实验研究

目的:观察人参总皂甙对由外源性羟自由基诱导的心肌细胞凋亡的影响。方法:利用第4代心肌细胞,随机分成7组,以10~(-3)mol/L 外源性羟自由基(OH~-)诱导心肌细胞凋亡为模型,分别观察4种不同浓度的人参总皂甙(25、50、100、150 mg/L)对心肌细胞存活率、形态学、心肌细胞凋亡百分率、DNA 琼脂糖凝胶电泳等参数的影响。结果:与凋亡组比较,加用不同浓度的人参总皂甙各组,随着人参总皂甙浓度升高,心肌细胞存活率明显升高,心肌细胞凋亡程度降低,呈剂量依赖性。结论:人参总皂甙能抑制由外源性羟自由基诱导的心肌细胞凋亡。     

当归、红芪超滤膜提取物对培养乳鼠心肌细胞缺氧-复氧损伤的影响

目的探讨当归、红芪超滤膜提取物对心肌细胞缺氧/复氧损伤的影响。方法通过给原代培养乳鼠心室肌细胞进行缺氧1h/复氧1h,建立缺氧/复氧（A/R）心肌细胞损伤模型。于复氧期开始随机将心肌细胞分为正常对照组（C）、缺氧/复氧组（A/R组）、药物低剂量组（LD）、药物高剂量组（HD）,于药物作用24h后测定各组缺氧/复氧后细胞损伤指标肌酸激酶（CK）、丙二醛（MDA）、超氧化物歧化酶（SOD）、髓过氧化物酶（MPO）。结果LD、HD组MDA、MPO、肌酸激酶（CK）明显较A/R组降低（P〈0.01）,SOD明显增高（P〈0.01）。结论当归、红芪超滤膜提取物（10万分子量）可减轻心肌细胞缺氧/复氧损伤。