体外诱导骨髓干细胞转化成心肌细胞的实验研究

目的　探讨 5 -氮胞苷 (5 -aza)浓度对骨髓基质干细胞 (MSCs)向心肌细胞转化的影响。方法　利用梯度离心法分离大鼠MSCs ;用 5 -aza对MSCs进行体外诱导转化 ,并使用心肌特异性抗体 (肌钙蛋白I和肌凝蛋白重链 )对诱导后的MSCs进行免疫组化染色 ,进行光镜和电镜观察。结果　分离培养后的MSCs生长密集 ,形态呈纺锤状 ,在 5 μmol/L和 10 μmol/L 5 -aza的诱导下分化成类心肌细胞 ,HE染色结果 :胞浆嗜酸性 ,免疫组化染色心肌特异性抗体阳性。电镜发现 :胞核居细胞中央 ,肌丝和幼稚肌结形成。结论　 5 -aza是促进干细胞向心肌细胞转化的有效诱导剂 ,以 5 μmol/L的 5 -aza对MSCs向心肌细胞转化的影响最大。     

人肌纤生成调节因子1真核表达载体的构建及其在乳鼠心肌细胞中的表达

目的构建人肌纤生成调节因子1全长的真核表达质粒,并观察其在HEK293T细胞系及Sprague-Daw-ley乳鼠心肌细胞中的表达。方法从NCBI GenBank数据库中克隆得到人肌纤生成调节因子1基因(AF417001)全长序列,与真核表达载体质粒pcDNA3.1/Myc-His(-)B连接并转化大肠杆菌XL1-Blue,筛选阳性克隆,T7引物测序,转染细胞后以逆转录聚合酶链反应、Western Blotting方法检测人肌纤生成调节因子1的表达。结果pcDNA3.1/Myc-His(-)B-hMR-1质粒经测序证实目的基因序列正确,无碱基突变。该质粒转染到HEK293T细胞系和乳鼠心肌细胞后人肌纤生成调节因子1的转录水平及表达水平明显增高。结论成功构建了人肌纤生成调节因子1全长的真核表达载体并确定了简便有效的乳鼠心肌细胞瞬时转染方法。     

心肌细胞缺氧／复氧损伤模型研究与应用进展

心肌细胞缺氧,复氧损伤模型是体外筛选抗心肌缺血,再灌注损伤活性物质的模拟模型,有效建立该模型是筛选结果可靠的保证。本文从心肌细胞缺氧,复氧损伤模型建立的一般程序,心肌细胞种类的选择与培养,心肌细胞缺氧腹氧损伤模型建立的方法等方面就近年来国内外心肌细胞缺氧,复氧损伤模型的研究与应用情况进行了综述,并就模型建．立中需要注意的相关问题进行了探讨。为有效复制该模型提供参考。     

新生小鼠心肌细胞的纯化培养与鉴定

目的建立新生小鼠心肌细胞(CM)的分离纯化、培养及鉴定的方法。方法采用酶消化法分离消化心室组织,差速贴壁法和化学方法纯化CM;培养7d后,利用免疫荧光技术和RT-PCR技术检测部分CM特异基因在蛋白和mRNA水平的表达;改进透射电镜的常规操作方法,观察CM超微结构。结果采用0.08%胰蛋白酶和0.04%胶原酶Ⅱ消化心室组织后,细胞成活率为98%,贴壁培养第3d出现同簇细胞的同步跳动;抗心肌肌钙蛋白(cTnT)免疫荧光染色阳性率为99.07%;以骨髓间充干细胞为阴性对照,RT-PCR结果显示CMα和β两型心肌肌球蛋白重链、cTnT基因表达呈阳性;经3%~4%琼脂预包埋法处理可以对少量细胞进行超薄切片的制作,CM具有正常的超微结构。结论建立了新生小鼠CM分离纯化培养和鉴定方法。     

新生大鼠心肌细胞原代培养方法的改进

目的：对新生大鼠心肌细胞分离培养方法进行改进,以期获得较高纯度和活力的心肌细胞;方法：采用胶原酶消化法分离大鼠心肌细胞,控制消化时间、消化温度、搅拌速度、离心次数和速度等,结合贴壁分离和Brd U干预纯化心肌细胞,流式细胞仪分析肌钙蛋白Ⅰ（troponin Ⅰ,Tn Ⅰ）表达,荧光探针进行胞浆游离钙离子染色;结果：多数心肌细胞自动收缩,逐渐聚集形成肌管,troponin Ⅰ阳性率达92％,所有心肌细胞钙离子染色阳性,并随细胞收缩呈周期性变化;结论：该方法分离培养的心肌细胞具有较高的纯度和活力。     

Survival and maturation of human embryonic stem cell-derived cardiomyocytes in rat hearts

Human embryonic stem cell (hESC)-derived cardiomyocytes are a promising cell source for cardiac repair. Whether these cells can be transported long distance, survive, and mature in hearts subjected to ischemia/reperfusion with minimal infarction is unknown. Taking advantage of a constitutively GFP-expressing hESC line we investigated whether hESC-derived cardiomyocytes could be shipped and subsequently form grafts when transplanted into the left ventricular wall of athymic nude rats subjected to ischemia/reperfusion with minimal infarction. Co-localization of GFP-epifluorescence and cardiomyocyte-specific marker staining was utilized to analyze hESC-derived cardiomyocyte fate in a rat ischemia/reperfused myocardium. Differentiated, constitutively green fluorescent protein (GFP)-expressing hESCs (hES3-GFP; Envy) containing about 13% cardiomyocytes were differentiated in Singapore, and shipped in culture medium at 4 degrees C to Los Angeles (shipping time approximately 3 days). The cells were dissociated and a cell suspension (2 x 10(6) cells for each rat, n=10) or medium (n=10) was injected directly into the myocardium within the ischemic risk area 5 min after left coronary artery occlusion in athymic nude rats. After 15 min of ischemia, the coronary artery was reperfused. The hearts were harvested at various time points later and processed for histology, immunohistochemical staining, and fluorescence microscopy. In order to assess whether the hESC-derived cardiomyocytes might evade immune surveillance, 2 x 10(6) cells were injected into immune competent Sprague-Dawley rat hearts (n=2), and the hearts were harvested at 4 weeks after cell injection and examined as in the previous procedures. Even following 3 days of shipping, the hESC-derived cardiomyocytes within embryoid bodies (EBs) showed active and rhythmic contraction after incubation in the presence of 5% CO(2) at 37 degrees C. In the nude rats, following cell implantation, H&E, immunohistochemical staining and GFP epifluorescence demonstrated grafts in 9 out of 10 hearts. Cells that demonstrated GFP epifluorescence also stained positive (co-localized) for the muscle marker alpha-actinin and exhibited cross striations (sarcomeres). Furthermore, cells that stained positive for the antibody to GFP (immunohistochemistry) also stained positive for the muscle marker sarcomeric actin and demonstrated cross striations. At 4 weeks engrafted hESCs expressed connexin 43, suggesting the presence of nascent gap junctions between donor and host cells. No evidence of rejection was observed in nude rats as determined by inspection for lymphocytic infiltrate and/or giant cells. In contrast, hESC-derived cardiomyocytes injected into immune competent Sprague-Dawley rats resulted in an overt lymphocytic infiltrate. hESCs-derived cardiomyocytes can survive several days of shipping. Grafted cells survived up to 4 weeks after transplantation in hearts of nude rats subjected to ischemia/reperfusion with minimal infarction. They continued to express cardiac muscle markers and exhibit sarcomeric structure and they were well interspersed with the endogenous myocardium. However, hESC-derived cells did not escape immune surveillance in the xenograft setting in that they elicited a rejection phenomenon in immune competent rats.     

Anthracycline-induced phospholipase A<Subscript>2</Subscript> inhibition

The purpose of this essay is to overview our findings that membrane-associated calcium-independent phospholipase A₂ is markedly inhibited by low, clinically relevant concentrations of anthracyclines. Our studies suggest that due to the essential role of this enzyme in membrane homeostasis, its inhibition can be one of the early culprits leading to anthracycline-induced cardiac dysfunction. The clinical importance and potential pharmaceutical use of this new phenomenon await further studies.     

大鼠心肌细胞结缔组织生长因子的诱导表达及RNA干扰研究

目的： 探讨心肌细胞对结缔组织生长因子（CTGF）的基础表达及转化生长因子β1（TGF-β1）对其分泌的诱导作用,并进一步研究以RNA干扰(RNAi)技术靶向抑制CTGF对下游纤维化因子的影响。方法: 实验分为以下5组： 组Ⅰ：单纯心肌细胞组;组Ⅱ：TGF-β1诱导组;组Ⅲ：阴性质粒组;组Ⅳ：RNAi组;组Ⅴ：脂质体组。分离培养Sprague Dawley（SD）大鼠乳鼠心肌细胞,以5 μg/L终浓度的TGF-β1对培养的心肌细胞进行诱导,再通过脂质体法将靶向大鼠CTGF的短发夹RNA(shRNA)干扰质粒转染入心肌细胞,流式细胞技术分选出成功转染的细胞。通过反转录聚合酶链式反应(RT-PCR)和免疫印迹（Western blotting）技术进一步研究各实验组心肌细胞CTGF、纤维连接蛋白（FN）mRNA及蛋白的表达水平。结果: 单纯心肌细胞组对CTGF、FN均有低水平的基础分泌,在予以TGF-β1诱导后表达水平显著升高（P＜0.01）;而在靶向特异性RNAi后,上述因子的表达均被显著抑制（P＜0.01）;并且纤维化因子FN的表达水平与促纤维化因子CTGF的表达显著相关。结论: 心肌细胞可自主低水平分泌或诱导后高表达CTGF及下游纤维化因子FN,提示心肌细胞主动参与了心肌纤维化及心脏重塑过程;而通过RNAi靶向抑制CTGF后可阻抑心肌细胞分泌下游纤维化因子,进一步提示CTGF是促心肌纤维化的关键性细胞因子,而RNAi是一种特异高效的很有前途的干预手段。