自体窦房结细胞异位移植治疗缓慢型心律失常的实验研究

Autologous sinoatrial node cells heterotopic transplantation for treating bradycardia:an experiment with dogs

目的探索自体窦房结细胞异位移植,构建心室异位起搏灶治疗缓慢型心律失常的可行性。方法将健康成年犬16只随机分为移植组和对照组(每组8只)。移植组切取窦房结组织并制成细胞悬液后,注射到自体右心室近心尖部心肌内,对照组切取窦房结后,于右心室相同部位注射等量培养液。2周后建立完全性房室传导阻滞动物模型并进行电生理检查。对移植组犬经股静脉注射异丙肾上腺素和阿托品,研究心率变化。免疫荧光染色观察移植的细胞存活状况及其与心室肌细胞形成的缝隙连接结构。结果消化分离成年犬窦房结得到的自主搏动的细胞结构和活性保持良好。建立完全性房室传导阻滞模型1 h 后,移植组犬心率(91±14)次/min 高于对照组(49±11)次/min(t=6.672,P<0.01),且此室性心律起源于细胞移植部位。注射异丙肾上腺素后,移植组室性心率由(95±11)次/min 增加至(118±15)次/min(t=3.497,P<0.01),而注射阿托品后室性心律无明显改变[分别为(95±11)次/min 和(101±17)次/min](t=0.838,P>0.05)。免疫荧光染色法证实,移植的细胞在移植部位存活,且细胞间有缝隙连接蛋白形成。结论成年犬窦房结细胞移植到自体右心室壁,能够提高完全性房室传导阻滞后的心室率,且对异丙肾上腺素反应良好,对阿托品无明显反应。移植的细胞可与周围细胞形成缝隙连接。

Objective To explore the feasibility of autografting sinoatrial nodal cells heterotopic transplantation to construct an ectopia pacemaker for treating bradycardia. Methods Sixteen healthy adult dogs were randomly divided into 2 equal groups： graft group and control group. The sinoatrial node （SAN） of the dogs in the graft group was harvested and digested into cell suspension in vitro, then injected to the autogenic right ventricular wall adjacent to heart apex. Commensurable culture medium was injected to the same position with the dogs in control group. Two week later, all dogs underwent transcatheter ablation of His bundle to create a complete heart block model and an electrophysiology study was carried out. In order to investigate the change of rhythm, isopruterenol and atropine was injected respectively to dogs of the graft group. Two weeks later the dogs were killed with their hearts taken out. Immunofluorescence histochemistry was used to investigate the survival of grafted cells and gap junction formed between grafted cells and ventricular myocytes. Results The isolated cells from SAN retained active and beating. After ablation, the heart rate of the dogs of the graft group was （91 ± 14）bpm, significantly higher than that of the control group, [ （49 ± 11 ） bpm, t = 6. 672, P 〈 0.01 ], and electrocardiography showed that these ventricular rhythms originated from the cell transplant sites. After the injection of isopruterenol the ventricular rate of the graft group was （ 118 ± 15 ） bpm, significantly higher than that before the injection, （95 ± 11 ） bpm, t = 3.491, P 〈 0.01 ）, however, after the injection of atropine, the heart rate of the graft group was （ 101 ± 17 ） bpm, not significantly different from that before the injection, [ （95 ± 11 ）bpm, t =0. 838,P 〉0.05]. Immunofluorescence staining showed that the grafted autografting sinoatrial nodal cells all survived and thatthere was connexin-43 expression among the cells. Conclusion Transplantation of autologous SAN cells into the right ventricular wall can boost the ventricular rhythm which is sensitive to isoproterenol but not to atropine. Grafted SAN cells can form gap junctions with adjacent myocytes.