局部注射5-氮胞苷修复猪心肌梗死后的心肌损伤

Repair of Swine Infarcted Myocardium with 5-azacytidine Intramyocardial Injection

目的探讨5-氮胞苷局部注入猪急性心肌梗死(AMI)区后对心肌损伤的修复作用。方法幼猪20只,开胸结扎冠状动脉前降支建立猪AMI模型;3周后治疗组(10只)通过局部注射将1mg/ml的5-氮胞苷溶液1ml注入梗死区及其周边;对照组(10只)予以等量的培养液接种;术后3周及7周分别行单光子发射计算机断层扫描(PET)检查;7周后处死所有动物,获取心肌标本,HE、免疫组化及2,3,5-氯化三苯基四氮唑(TTC)染色观察损伤心肌的转归。结果PET示治疗组7周时可见前壁、心尖部放射性分布较3周时密集;对照组7周与3周比较无明显差异。TTC染色治疗组梗死区面积及所占百分比显著小于对照组,[(4.06±0.29)cm2vs(5.41±0.28)cm2;(16.34±0.89)vs(21.23±1.02)%,P<0.001]。HE染色治疗组梗死区可见散在带横纹的肌肉组织,电镜下新生细胞之间未见闰盘连接;免疫组化染色这些细胞肌球蛋白重链β(β-MHC)、心脏肌钙蛋白Ⅰ(cTnⅠ)及连接蛋白43(Cx43)呈阳性。对照组梗死区为均匀一致的纤维疤痕组织。结论5-氮胞苷局部注入猪AMI区后可以诱导产生新的带横纹的肌细胞,修复心肌损伤。

Objective To study swine infarcted myocardium repairment after 5-azacytidine intramyocardial injection.Methods Twenty young swines were divided into the treatment and control group randomly.The acute myocardial infarction（AMI）models were made by ligating the left anterior descending（LAD）as previously described.After 3 weeks,1 ml 5-azacytidine in 1 mg/ml concentration was intramyocardium injected into infarcted and border regions in the treatment group（n=10）.In the control group（n=10）,the same volume of cell culture medium was injected into infarcted myocardial tissue through intramyocardium.Positron emission tomography（PET）was examined at 3rd weeks and 7th weeks.After 7 weeks,the animals were killed,the specimens were harvested for triphenyltetrazolium chloride（TTC）and HE staining,electron microscopical studies and immunohistochemical examination for β muscle heavy chain（β-MHC）,cardiac troponin Ⅰ（cTnⅠ）and connexin43（Cx43）.Results PET demonstrated that radioactivity in the left ventricular free wall and apex became thick in the animals in the treatment group at 7th week compared with the animals in the control group.The infarcted area stained with TTC method and its percentage had significant difference between the treatment and the control group[（4.06±0.29）cm2 vs（5.41±0.28）cm2;（16.34±0.89）% vs（21.23±1.02）%,P0.001].New island and striated muscles were found in the treatment group at the site of injection.Actin were filaments with transmission electron microscopy found but not intercalated discs in the new muscle cells;these cells were positive with cellular immunohistochemical stain on β-MHC,cTnI and Cx43.There were symmetrical fibrous scar tissue with negative immunohistochemical result in the infarcted area in the control group.Conclusion 5-azacytidine intramyocardial injection could repair swine myocardium injury.