A Mouse Model of Donor Heart Lymphatic Ablation <em>via</em> Electrocautery for Transplantation Research

Although cardiac lymphatic vessels have garnered increasing attention in recent years, the relationship between the donor cardiac lymphatic system and acute rejection in heart transplantation remains to be elucidated. Cardiac electrophysiological activity was assessed via electrocardiography (ECG) in normal mice before and after cardiac lymphatic ablation. Major lymphatic vessels of donor hearts were visualized by Evans Blue injection and subsequently ablated via electrocautery. A heart transplantation model featuring donor cardiac lymphatic dysfunction was established using hearts subjected to lymphatic ablation. Cardiac graft function was assessed via echocardiography, western blotting, and ELISA. The impact of donor lymphatic ablation on acute rejection was assessed by hematoxylin-eosin (HE) staining and monitoring of graft survival time. ECG results indicated no significant changes in cardiac electrophysiology before and after lymphatic ablation, confirming that major cardiac vessels remained undamaged. Evans Blue was injected into the cardiac apex to label the lymphatic vessels. Major lymphatics were then ablated using electrocautery. Following the completion of the ablation procedure, the mice were heparinized, and their hearts were subsequently harvested. The aorta and pulmonary artery were transected, and the superior/inferior vena cava, along with the pulmonary veins, were ligated. The prepared (ablated) donor hearts were then transplanted. Levels of cTnI and ejection fraction demonstrated that lymphatic ablation did not exacerbate cardiac injury. HE staining revealed that ablation of donor cardiac lymphatics alleviated acute rejection, reduced myocardial injury, and prolonged graft survival. We successfully established a murine heart transplantation model with donor cardiac lymphatic dysfunction and demonstrated that ablation of donor cardiac lymphatics can mitigate acute rejection, attenuate myocardial damage, and extend graft survival. These findings provide new insights and a foundation for understanding the role of the cardiac lymphatic system in heart transplantation.