同种异体心肌细胞移植治疗缓慢性心律失常的实验研究

探讨新生心肌细胞移植重建心脏优势起搏点治疗缓慢性心律失常的可行性。采用酶法分离新生Yorkshire猪右房组织(包括窦房结),获取单个心肌细胞,差速贴壁法纯化,4,6-二脒基-2-苯基吲哚(DAPI)标记后制备成5×106个/ml心肌细胞悬液,开胸直视下将1ml悬液注入细胞移植组幼年猪左室游离壁(n=5),对照组(n=5)注入等体积培养基,移植前3天开始应用环孢素A和泼尼松龙抑制免疫排斥反应。移植3周后应用射频消融技术打断His束造成Ⅲ度房室阻滞。分别应用心电图、Holter、心腔内起搏标测和免疫荧光显像进行电生理学评价和组织学观察。结果:His束消融后,两组动物均形成Ⅲ度房室阻滞。细胞移植组室性节律频率显著快于对照组(移植组平均为95次/分,对照组为32次/分)。心腔内起搏标测证实细胞移植组室性心律起源于细胞移植区。对照组均在24h内发生心室颤动死亡。心脏组织冰冻切片可见DAPI标记的呈蓝色荧光的移植细胞核,移植细胞与宿主心肌细胞间有连接蛋白43和N型钙粘素的表达。结论:移植的心肌细胞可在宿主心脏存活并与周围细胞发生电连接,并主导心室节律。

Transplanted Neonatal Cardiomyocytes as A Potential Biological Pacemaker in Pigs With Complete Atrioventricular Block

The aim of this study is to prove the hypothesis that the cardiomycytes with a higher intrinsic rhythmic rate which are transplanted into the left ventricle could act as an ectopic pacemaker. Dissociated neonatal atrial cardiomyocytes including sinus nodal cells were injected into the free wall of the left ventricle of male pigs (n=5). In the control group (n=5) medium was used for injection. 3 weeks after cell/medium injection the pigs underwent catheter ablation of the atrioventricular node. All animals took serial ECG and Holter monitoring before cell/medium injection and repeated after atrioventricular node ablation. Immunofluorescence was used to assess the survival of grafted cells and expression of gap junction between grafted and host cardiomyocytes. Results:The ventricular ectopic beat rate compared with control injection after atrioventricular block (95 bpm vs 32 bpm) was significantly increased by transplantation of atrial cardiomyocytes. Electrophysiological mapping demonstrated that the idioventricular rhythm originated from the cell-injection site. Morever, connexin43 and N-cadherin between grafted and host cardiomyocytes was expressed with immunofluorescence examination. Conclusion:Grafted neonatal atrial cardiomyocytes are able to survive and electrically integrate into the host myocardium, and show a pacing function that can be modulated by autonomic agents.