Mitochondrial Ischemia-Reperfusion Injury of the Transplanted Rat Heart

Abstract

Cold ischemia time and preservation of organs are limited by I/R injury leading to primary nonfunction of the graft. In a rat heart transplant model, we compared cardioplegic St Thomas (ST) to histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin preservation solutions in terms of contractile function, and mitochondrial respiratory and enzymatic defects after prolonged cold ischemia and reperfusion. Contractile function was scored after transplantation and 24 h of reperfusion. Mitochondrial function was investigated by high-resolution respirometry of permeabilized myocardial fibers. Graft performance in terms of contractile function declined with the duration of cold storage. Recovery was significantly improved after 10 h of cold storage in HTK compared with ST (cardiac scores, 3.3+/-0.5 and 1.8+/-0.8, respectively). Tissue lactate dehydrogenase was better preserved in HTK than ST. Increase of tissue water content (edema) was less pronounced in HTK than ST (3.33+/-0.14 and 3.73+/-0.21 mg/mg dry weight, respectively). Similar cardiac scores (2.6+/-0.9 and 2.9+/-1.2, respectively) and mitochondrial respiratory parameters were obtained after preservation in HTK and University of Wisconsin. Decline in contractile function of individual grafts correlated well with loss of mitochondrial respiratory capacity, whereas citrate synthase activity remained largely preserved, indicating specific damage of respiratory complexes. Our data provide evidence for the superiority of preservation solutions versus a cardioplegic solution for prolonged cold storage of the heart. The correlation of graft performance and mitochondrial function indicates the potential of high-resolution respirometry for quantitative assessment of myocardial injury upon cold I/R, providing a basis for diagnostic approaches and evaluation of improved preservation solutions for heart transplantation.

Impact of Cold Ischemia on Mitochondrial Function in Porcine Hearts and Blood Vessels

“…Although this method is not able to separately investigate mitochondrial subpopulations, it provides a novel sensitive approach for monitoring mitochondria-related injuries in small biopsies and may find use in the development and evaluation of newly designed preservation solutions. In accordance with previous data [25], we demonstrate here that Custodiol-HTK preservation solution can be effective for the protection of mitochondrial function also in the pig myocardium when exposed to cold ischemia.…”

“…Furthermore, pulmonary hypertension in heart-transplant recipients may significantly impair the right ventricle of the donor heart, which is not adapted to such high pressure-levels. This study thereby contributes to the existing but incongruent knowledge of the superiority of preservation solution over purely saline solutions [25]. Also, investigation of the mitochondrial damage together with the analysis of the associated changes in the respiratory chain give a better insight into the mechanism of damage resulting in the impaired function [7,9,25,26].…”

Hypoxia-Induced Alteration of Mitochondrial Genes in Cardiomyocytes

“…The information on molecular changes occurring in mitochondria of the cardiomyocytes following conditions such as hypoxia is important in understanding the molecular basis of the pathobiology associated with low oxygen conditions(1; 2; 19). Studies have shown that alterations in activity or expression of transcription factors acting on nuclear DNA mediate the shifts in energy production and substrate utilization (11; 20; 21).…”

Microcirculatory, mitochondrial, and histological changes following cerebral ischemia in swine

“…Respiration was measured using Oxygraph-2k (OROBOROS Instruments, Innsbruck, Austria) at 37°C in 2 mL of medium containing 110 mM KCl, 0.45 M MgCl 2 , 5 mM KH 2 PO 4 , and 10 mM Tris–HCl, pH 7.2 [15]. Datlab software (OROBOROS Instruments) was used for data acquisition and analysis.…”