Objective To investigate improvement of the engineered cardiac tissue (ECT)constructed by neonatal rats and liquid collagen type I implantation on the myocardial electrophysiological characteristics after myocardial infarction(MI)in the rats by microelectrode array chip.Methods Engineered cardiac tissue was constructed by mixing cardiomyocytes isolated from the neonatal rats and liquid collagen type I as scaffold.Left anterior descending(LAD)coronary arteries of rats were ligatured to establish MI models.In control group thoracotomy and cardiac exposure was conducted but without LAD ligation.Forty-eight adult male Wistar rats were selected and divided randomly into four groups:control group (n =12),MI group(n =12) and MI+transplantation group(n=12),MI+sham-transplantation group(n =12).After four weeks,the ECG were recorded,and all hearts were intubated through aorta and perfused by the Langendorff apparatus with Tyrodes solution,and we recorded the field potential and electrical coupling between ECT and host with microeletrode arrays technique.cTnT,Ⅷ factor,connexin43 were measured by immunofluorescence staining,the results and collect images were observed under lasers scanning confocal microscopy.Results Transplanted ECT was covering the infarcted myocardium tightly,and had better biological activity.There were plenty of vascularization,and connexin43 was widely formed between ECT and the host.Echocardiography evaluation 4 weeks after infarction showed enlargement of left ventricular end-diastolic volume,decreased left ventricular ejection fraction.ECT reduced the enlargement of the volume LVED and increased the EF which were not restored to normal.Compared with the control group,ECG showed the expected QRS and QT interval prolonged in MI group(P=0.01).In MI+graft group QRS and QT interval shortened(P=0.03)but didn't restored to normal.We assessed electrical coupling of grafts to the host myocardium 4 weeks after engraftment by MEA.MI group showed the obvious delay of impulse propagation and decrease of amplitude in infarcted anterior and lateral segment (P=0.01).In contrast,epicardial activation in graft rats showed an increase in amplitude (P=0.01)and a shorten in field potential duration(P=0.02).Electricity impulse represented anisotropic alteration in MI group,and there was improvement in MI+graft group.Conclusion Engineered heart tissue grafts can improve electrical conduction and cardiac function as well as mechanical remodeling in infarcted rat hearts.Cardiac tissue engineering is a promising material for the repair of heart function and electrical injury in vivo.%目的 应用微电极阵列芯片(MEA)标测技术评价液态Ⅰ型胶原与新生大鼠心肌细胞混合构建工程化心肌组织(ECT)移植于大鼠陈旧性心肌梗死(MI)区后对心肌电重构的改善作用.方法 采用液态Ⅰ型胶原与新生大鼠心肌细胞混合培养构建ECT片层.48只成年雄性Wistar大鼠,随机分为4组:对照组、MI组、MI+片层移植组(MI+graft组)、MI+假片层移植组(MI+sham-gaft组),每组12只.对照组开胸不结扎动脉,其余各组结扎左冠状动脉前降支,建立大鼠MI模型.MI模型建立2周后行ECT移植.分别于术前及移植后2周行心电图及超声检测,采用主动脉逆行插管Langendorff法灌流心脏,MEA对ECT与宿主心肌之间的电偶联进行检测并记录心肌场电位.取心将ECT横切后采用免疫荧光染色心肌肌钙蛋白T(cTnT)、Ⅷ因子、连接蛋白43(Cx43),在激光扫描共焦显微镜下观察结果,采集图像数据.结果 移植的ECT紧密贴于MI部位,存活良好,有较丰富血管化的发生,在ECT中细胞间和与宿主之间形成了较为广泛的Cx43连接.MI+graft组较MI组左心室舒张末期容积缩小,左心室射血分数增加,但仍不能恢复正常.MI组术后4周较术前QRS时限、QT间期延长(P=0.01),MI+graft组比MI组QRS时限、QT间期缩短(P=0.03),仍比对照组长.MEA记录MI组MI区场电位振幅较对照组明显降低(P=0.01),时限明显延长(P=0.01)；MI+graft组场电位较MI组振幅增加(P=0.01),时限缩短(P=0.02),但较对照组仍未完全恢复.对照组场电位激动传导呈顺序梯度传导.MI组传导不均一性增加,传导梯度样改变消失,MI+graft组使MI面心室肌电活动略呈均一性传导,但较对照组仍未完全恢复.结论 移植的ECT能改善MI大鼠心室肌的收缩功能及电传导时间,可部分修复心脏功能,组织工程化心肌组织有望用于心肌组织的缺损修复.
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