<h3>Purpose</h3> Microvascular dysfunction (MVD) in cardiac allografts is associated with allograft vasculopathy, graft failure, and death after heart transplantation. Prolonged ischemia and pronounced ischemia/reperfusion injury promote MVD. Circulatory death (CD) donor hearts are exposed to a warm ischemic period followed by machine (re)perfusion (MP) with warm blood. The novel histidine-tryptophane-ketoglutarate(HTK)-N solution has been developed to improve myocardial contractility and preserve the vascular viability of donor hearts. The impact of MP with hypothermic, oxygenated HTK-N solution on microvascular function has not been investigated yet. <h3>Methods</h3> In a pig model of CD, the microvascular function of hearts was either assessed for 60 min immediately after harvesting (CD-group) or hearts were maintained by MP with normothermic blood (CD-B group), hypothermic HTK (CD-HTK group), or HTK-N (CD-HTK-N group) solution for 4 h before microvascular evaluation (all N=5 per group). We measured microvascular blood flow (LDP) by a Laser-Doppler-Perfusion needle probe in the left ventricular (LV) wall in dependence of a balloon-induced LV-preload to evaluate the microvascular function. We analyzed the Immunoreactivity of intracellular (ICAM), vascular (VCAM), and platelet-endothelial (PECAM) cell adhesion molecules, as well as endothelial nitric oxide synthase (eNOS) of arterioles, and profiled the expression of 84 genes. We constructed gene expression networks using the Boruta machine learning algorithm for feature selection. <h3>Results</h3> Relative LDP (rLDP) was majorly improved by HTK-N perfusion (1.16±0.06) compared with the CD-group (0.96±0.07, p=0.142), CD-B- (0.86±0.07, p=0.016) and CD-HTK-group (0.92±0.04, p=0.065). After MP with HTK-N, the expression of endothelial viability marker eNOS majorly increased, and the expression of endothelial injury markers ICAM, VCAM, and PECAM majorly decreased. The groups CD and CD-B showed fragmented gene networks with heterogenous gene correlation. After HTK and HTK-N perfusion, groups showed centralized networks with homogenous correlation and majorly reconstituted cluster regions. <h3>Conclusion</h3> MP with HTK-N counteracts MVD, preserves the microvascular endothelium, and reduces the expression of cell adhesion molecules in the coronary microvasculature of CD-hearts.