ABSTRACT
BACKGROUND: The content of type Ⅰ and Ⅲ collagen and the ratio of both are crucial factors to promote heart geometric morphology change,and ventricular systolic and diastolic myocardial performance.Matrix metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase 1 (TIMP1) are primary regulatory substances of collagen metabolism.After myocardial infarction,chronic heart failure rats were subjected to bone marrow meseuchymal stem cell transplantation.What changes in MMP-2 and TIMPI would occur?OBJECTIVE: To observe the content of type Ⅰ and Ⅲcollagen and the ratio between both,as well as expression levels of MMP-2 and TIMP1 in the left ventricular tissue of rats with myocardial infarction-caused chronic heart failure following bone marrow mesenchymal stem cell (MSC) transplantation.DESIGN: A randomized controlled experiment.SETTING: Department of Senile Angiocardiopathy,General Hospital of Chinese PLA & Department of Biochemistry,Peking University Health Science Center.MATERIALS: This study was performed at the laboratory of Department of Biochemistry,Peking University Health Science Center between July 2004 and December 2005.Male Sprage Dawley rats of clean grade,aged 4 weeks old,were provided by the Laboratory Animal Center,Beijing Medical University and used for preparation of MSCs.Fourteen female rats,weighing 200-250g,were developed into models of heart failure-caused by myocardial infarction.METHODS: MSCs were isolated and,purified by gradient centrifugation and adherent cells were allowed to proliferate.Female rats underwent coronary artery ligation to induce chronic ischemic heart failure.Four weeks later,the rats were randomly divided into 2 groups: (1) experimental group (n=7),rats received transplantation of MSCs harvested from male rats [5×106 in 50 μL phosphate buffered saline(PBS)]by injection into the ischemic myocardium; (2) control group (n=7),rats received the same volume of PBS.MAIN OUTCOME MEASURES: Twenty-one days after therapy,(1) left ventricular fusion was tested by hematoxylin-eosinstaining and Masson staining; (2) Expression of MMP-2 and 1TMPI as well as contents of type I and llI collagen was analyzed by immunohistochemistry; (3) MMP-2 and TIMP1 expression levels were examined by Western blot.RESULTS: Fourteen rats were included in the final analysis.Type Ⅰ collagen expression in the scar area was much higher in theexperimental group than in the control group,while type Ⅲ collagen expression was much lower in the experimental group.MMP-2 expression was reduced and TIMPI expression was increased in the experimental group compared with the control group.Together,ventricular wall was thickened,ventricular chamber was reduced,and heart function was strengthened in the experimental group compared with the control group.CONCLUSION: MSC transplantation alleviated left ventricular remodeling in chronic ischemie heart failure,which results from dynamic regulation of MMP-2/TIMP1.
ABSTRACT
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.