钙离子ATP酶2a基因修饰骨髓间充质干细胞移植改善慢性心力衰竭大鼠的心功能

背景:目前仍缺乏有效手段修复心力衰竭后受损心肌,逆转心肌病理性重塑.作为一种新的治疗策略,用正常肌细胞和治疗性基因干预受损心肌正逐渐显示出其在改善心功能方面的优势.目的:观察腺病毒转染不同代骨髓间充质干细胞的有效性和稳定性.并以携带肌浆网钙离子ATP酶(sarcoplasmic reticulum Ca(2 ) ATP-ase,SERCA2a) 基因的腺病毒转染骨髓间充质干细胞,治疗心力衰竭大鼠,比较SERCA2a基因治疗,骨髓间充质干细胞移植以及骨髓干细胞基础的SERCA2a基因治疗慢性心力衰竭大鼠的效果.设计:随机对照实验.单位:解放军总医院老年心血管病科和北京医科大学生物化学系.材料:选取购于北京医科大学动物实验中心的4周龄雄性SD大鼠作为骨髓供体.选取体质量200～250 g雌性成年SD大鼠作为细胞移植和基因治疗受体.以雄性大鼠Y染色体sry基因鉴定供体移植细胞是否在雌性大鼠受体心肌内存活.实验所用Ad-SERCa2a,Ad-EGFP的构建由我科鲁小春博士完成;第3和8代骨髓间充质干细胞自行分离培养.方法:实验于2004-07/2005-12在北京医科大学生物化学系周春燕实验室完成.对30只雌性SD大鼠进行左冠状动脉结扎,制作急性心肌梗死后慢性心力衰竭大鼠模型.将造模成功的29只大鼠随机分为4组:基因治疗组7只,干细胞移植治疗组7只,基因修饰的干细胞移植组8只,腺病毒空载体对照组7只,分别予以单纯SERCA2a基因、MSC移植、SERCA2a基因修饰的骨髓间充质干细胞移植及腺病毒空载体干预.分离培养大鼠骨髓间充质干细胞,用携带SERCA2a及绿色荧光蛋白的腺病毒(Ad-SERCA2a-GFP)转染第3和8代骨髓间充质干细胞.主要观察指标:采用流式细胞仪检测不同代骨髓间充质干细胞的Ad-SERCA2a-GFP转染率.分别在治疗前及治疗后14,21 d采用超声心动图检测大鼠心功能.采用免疫组化法检测大鼠心脏Ⅷ因子表达;采用RT-PCR 和Western杂交检测SERCA2a的基因和蛋白水平表达,并按照说明书检测宿主SERCA2a功能活性.结果:①转染率:腺病毒转染不同代骨髓间充质干细胞的转染率超过80%,第3代骨髓间充质干细胞与第8代的转染率比较,差异无显著性意义(P > 0.05).②大鼠心功能:治疗后14 d,与腺病毒空载体对照组相比,其余3组左室射血分数均明显升高(P < 0.01).治疗后 21 d,与腺病毒空载体对照组相比,干细胞移植治疗组和基因修饰的干细胞移植组大鼠室壁增厚;干细胞移植治疗组和基因修饰的干细胞移植组左室射血分数和左室短轴缩短率改善率持续升高(P < 0.01),基因治疗组两指标改善率较治疗14 d时下降.与腺病毒空载体对照组相比,基因修饰的干细胞移植组左室前壁和室间隔收缩期纵向峰值速度显著升高(P < 0.01),左室前壁和室间隔舒张期纵向峰值速度亦呈现相同改善(P < 0.01).③心肌SERCA2a的基因、蛋白水平表达和功能活性,以及Ⅷ因子表达:携带SERCA2a基因的骨髓干细胞在宿主心肌能有效地合成和表达有功能的SERCA2a蛋白.与腺病毒空载体对照组相比,基因修饰的干细胞移植组SERCA2a基因、蛋白表达和酶活性均显著增强.干细胞移植组心力衰竭大鼠心脏瘢痕区可观察到Ⅷ因子表达.结论:①第3和8代骨髓间充质干细胞均具有高腺病毒转染率,骨髓间充质干细胞是基因治疗的良好细胞载体,其介导的SERCA2a基因治疗对衰竭心肌具有持续稳定的心功能改善作用.②骨髓间充质干细胞移植改善心功能的作用可能与促进血管新生有关.

Enhancement of cardiac function of chronic heart failure rats by marrow stromal cell-based sarcoplasmic reticulum Ca2+ adenosine triphosphatase gene therapy

BACKGROUND: There are still few effective methods to repair injured myocardium after myocardial failure and pathologically rebuild reverral myocardium. As a new therapy, normal myocytes and therapeutic gene to interfere injured myocardium have advantageous effects in improving heart function.OBJECTIVE: To observe the efficiency and stability of adenovirus-medicated gene transferred into different passages of bone marrow mesenchymal stem cell (MSC) and investigate the effect of MSC-based sarcoplasmic reticulum Ca2+ ATPase gene (SERCA2a) gene therapy for rats with chronic heart failure. To compare the effects of gene therapy, cell transplantation and MSC-based SERCA2a gene therapy for chronic heart failure. DESIGN: Randomized controlled study.SETTING: Department of Senile Angiocardiopathy, General Hospital of Chinese PLA; Department of Biochemistry, Beijing Medical University. MATERIALS: Male Sprague-Dawley (SD) rats with 4 weeks old, clean grade and weighing 45-50 g provided by the Animal Experimental Center, Peking Medical University were used as donators of bone marrow. Other female SD rats of 12 weeks old, clean grade and weighing 200-250 g were used as receptors of cell transplantation and gene therapy. Sry gene of Y chromosome in male rats was used to evaluate whether transplanted cells of donators lived in myocardium of receptor rats. Ad-SERCa2a and Ad-EGFP were constructed by Doctor Lu Xiao-chun; MSC in the 3rd and 8th generations was isolating cultured on its own. METHODS: The experiment was carried out in the Zhou CY Laboratory (BSL-2), Department of Biochemistry, Beijing Medical University from July 2004 to December 2005. Thirty female SD rats received ligation at the left coronary artery to make models with chronic cardiac failure following acute myocardial infarction. And then, 29 rats were randomly divided into four groups, including gene therapy group (n=7), MSC group (n=7), gene-modified MSC group (n=8) and control group (n=7). Rats in the four groups were given the interventions of SERCA2a gene, MSC transplantation, MSC+Ad/SERCa2a and empty adenoviral vector, respectively. MSCs were separated and cultured, and then Ad-SERCA2a-GFP was used to transfer MSC in the 3rd and 8th generations.MAIN OUTCOME MEASURES: Ad-SERCA2a-GFP transfection rate of MSC was measured by using flow cytometer. Before and at 14 and 21 days after treatment, cardiac function was evaluated by ultrasonic echocardiogram. Expression of cytokine Ⅷ was tested by immunohistochemical staining. SERCA2a gene and protein expression were evaluated by RT-PCR and Western blot respectively, as well as SERCA2a enzyme activity. RESULTS: ① Transfection rate: The infection efficiency of adenovirus-medicated gene into different passages of MSC was over 80%, and there was no difference between passage three (P3) MSC and P8 MSC (P > 0.05). ② Heart function: Left ventricle wall was thickened obviously in group MSC and group MSC+Ad/SERCa2a on the 21st day after treatment, while volume was shortened and gradually rounded. Compared to control group, ejection fraction (EF) and shortening fraction (FS) of group Ad-SERCa2a, group MSC and group MSC+Ad/SERCa2a were elevated significantly on the 14th day after therapy (P < 0.01). While the elevation values of EF and FS began to reduce in group Ad-SERCa2a on 14th day after therapy, it continued to increase in both group MSC and group MSC+Ad/SERCa2a (P < 0.01). Improvement rate of EF at 21 days after therapy (EF D21) increased in group MSC and group MSC+Ad/SERCa2a respectively, but decreased in group Ad-SERCa2a. Compared to group Ad-SERCa2a, peak systolic flow velocity of anterior wall and interventricular septum in group MSC+Ad/SERCa2a increased significantly on the 21st day after therapy, and peak diastolic flow velocity of anterior wall and interventricular septum elevated in group MSC+Ad/SERCa2a, too (P < 0.01). ③ SERCA2a gene, protein expression and enzyme activity in group MSC+Ad/SERCa2a were significantly stronger in group MSC and control group. Parts of MSC transplanted into scar zone expressed Ⅷ.CONCLUSION: ① MSC is an effective platform for the targeted delivery of therapeutic gene. It suggests that different passages of MSC from P3 MSC to P8 MSC are regarded as high-effectively gene vehicles. MSC-based SERCA2a gene therapy showed much strong and lasting beneficial effect on exhausted myocardium. ② Effect of MSC transplantation on improving heart function may be related to promoting vascular neogenesis.