Ex Situ Perfusion with Histidine-Tryptophan-Ketoglutarate-N Improves Myocardial Microvascular Circulation and Diastolic Dysfunction of Porcine Donor Hearts

Background: An impaired coronary microvascular circulation in cardiac allografts is associated with diastolic dysfunction, graft failure, and death after heart transplantation. Ischemia/reperfusion (IR) injury impairs contractility and coronary microvascular circulation. Ex situ blood perfusion (ESBP) is a novel method for donor heart maintenance, reducing the time of cold ischemia. Nevertheless, ESBP adds another reperfusion period to the donor heart. The novel histidine-tryptophan-ketoglutarate (HTK)-N solution has been developed to improve myocardial contractility and vascular function of donor hearts. The impact of ex situ perfusion with oxygenated HTK-N solution on coronary microvascular circulation and diastolic function has not been investigated yet.

Method: The microvascular and contractile function of porcine hearts were either assessed for 60 minute immediately after harvesting (control), or hearts were maintained by ex situ blood perfusion (BP group), hypothermic perfusion with traditional HTK (HTK group), or novel HTK-N (HTK-N group) for 4 hours before microvascular evaluation (N = 5 per group). We measured myocardial microcirculation (LDP) by a laser-Doppler perfusion needle probe in the left ventricular anterior wall. We measured contractility with a balloon catheter inserted through the mitral valve. We performed immunohistochemical staining of intracellular (ICAM), vascular (VCAM), and platelet-endothelial (PECAM) cell adhesion molecules, as well as endothelial nitric oxide synthase (eNOS) of arterioles. We profiled the expression of 84 genes and performed a pathway analysis.

Results: The diastolic pressure decrement (HTK-N: −1,703 ± 329 mm Hg/s; HTK: −1,093 ± 97 mm Hg/s; BP: −690 ± 97 mm Hg/s; p < 0.05) and relative LDP (HTK-N: 1.42 ± 0.12; HTK: 1.11 ± 0.13; BP: 1.22 ± 0.27; p < 0.05) were improved only after HTK-N perfusion. After HTK-N perfusion, the expression of eNOS increased, and ICAM and VCAM decreased. Only after BP compared with control, pathways involved in complement and coagulation cascades, focal adhesion, fluid shear stress, and the IL-6 and IL-17 pathways were upregulated.

Conclusion: In conclusion, ex situ perfusion with HTK-N counteracts diastolic dysfunction, improves microvascular circulation, and reduces microvascular IR injury in porcine hearts.

Publikationsverlauf

Artikel online veröffentlicht:
28. Januar 2023