Książek Agnieszka A, Mitchell Katharyn J, Morax Laurent, Schwarzwald Colin C, Hoerstrup Simon P, Weber Benedikt
Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland.
Eur Surg Res. 2016;57(3-4):171-185. doi: 10.1159/000446515. Epub 2016 Jul 20.
Heterotopic heart transplantation (HHT) in rodent animal models represents an important technique enabling studies on organ transplantation immunology and pharmaceutical development. Recent investigations used nonworking HHT designs, with the left ventricle (LV) bypassed in the anastomosis system. In spite of their principal success, the lack of orthogonal ventricular filling leads to myocardial atrophy. However, when focusing on the cellular and molecular mechanisms involved in the in vivo remodeling of the myocardium or cell-based cardiovascular implants, a nonworking model is suboptimal as it lacks the native-analogous hemodynamic and metabolic situation. Here we present the hemodynamic and electrical assessment of a biventricularly loaded murine HHT method without the need for a combined heart-lung transplantation approach.
Heterotopic transplantations (n = 13) were performed on C57BL/6J-(H-2b) inbred mice (n = 13 donors, n = 13 recipients) by creating end-to-side anastomoses between the donors' cranial vena cava (CrVC) and the recipients' abdominal caudal vena cava (CVC), between the donors' ascending aorta and the recipients' abdominal aorta (aAo), and between the grafts' pulmonary trunk and the left atrium. After transplantation, a hemodynamic assessment using echocardiography (including 2D speckle tracking analysis) and electrocardiography was performed.
The loaded HHT procedure in the mice was performed with an overall success rate of 61%. In 3 of the remaining 5 cases, only atrial function was restored. The median duration of the entire surgical procedure for the recipient animal was 190 (IQR 180-250) min. The mean heart rate in the loaded HHT group was 355 ± 6 bpm in comparison to the control group with an in situ heart rate of 418 ± 61 bpm. A native-like closing and opening pattern of the aortic and mitral valves (visible on both 2D and M-mode images) was observed, confirming a native-analogous loading of the LV. Pulsed-wave Doppler provided visualization of the flow across the region of anastomoses between the pulmonary trunk and the left atrium, reaching a mean maximum velocity of 382 ± 12 mm/s. Exemplary 2D speckle tracking analysis of the LV free wall and interventricular septum revealed some differences in vector directions in one animal when compared to the orthotopic native heart, indicating an asynchronous movement of the LV.
These results demonstrate the technical (micro)surgical feasibility of a fully loaded HHT procedure in the murine model without using a combined heart-lung transplantation approach. The acute hemodynamic performance of the HHT grafts approximated the native orthotopic situation. This model may open up new options for the investigation of cellular and molecular questions in the murine cardiovascular in vivo system in the near future.
啮齿动物模型中的异位心脏移植（HHT）是一项重要技术，可用于器官移植免疫学研究和药物开发。最近的研究采用了非功能性HHT设计，在吻合系统中绕过左心室（LV）。尽管取得了主要成功，但缺乏正交心室充盈会导致心肌萎缩。然而，当关注心肌体内重塑或基于细胞的心血管植入物所涉及的细胞和分子机制时，非功能性模型并不理想，因为它缺乏类似天然的血流动力学和代谢情况。在此，我们展示了一种双心室负荷的小鼠HHT方法的血流动力学和电评估，无需联合心肺移植方法。
对C57BL/6J-（H-2b）近交系小鼠（13只供体，13只受体）进行异位移植（n = 13），在供体的头腔静脉（CrVC）与受体的腹尾腔静脉（CVC）之间、供体的升主动脉与受体的腹主动脉（aAo）之间以及移植物的肺动脉干与左心房之间进行端侧吻合。移植后，使用超声心动图（包括二维斑点追踪分析）和心电图进行血流动力学评估。
小鼠的负荷HHT手术总体成功率为61%。在其余5例中的3例中，仅恢复了心房功能。受体动物整个手术过程的中位持续时间为190（IQR 180 - 250）分钟。负荷HHT组的平均心率为355 ± 6次/分钟，而对照组原位心率为418 ± 61次/分钟。观察到主动脉瓣和二尖瓣有类似天然的开闭模式（在二维和M型图像上均可见），证实了左心室有类似天然的负荷。脉冲波多普勒显示了肺动脉干与左心房之间吻合区域的血流，平均最大流速达到382 ± 12毫米/秒。对左心室游离壁和室间隔进行的二维斑点追踪分析示例显示，与原位天然心脏相比，一只动物的向量方向存在一些差异，表明左心室运动不同步。
这些结果证明了在小鼠模型中不采用联合心肺移植方法进行完全负荷HHT手术的技术（显微）外科可行性。HHT移植物的急性血流动力学性能接近天然原位情况。该模型可能在不久的将来为研究小鼠心血管体内系统中的细胞和分子问题开辟新的途径。
