Hours Of Ischemic Storage Research Articles

Combined endothelial and myocardial protection by endothelin antagonism enhances transplant allograft preservation

Endothelin is a potent inflammatory peptide associated with myocardial dysfunction, coronary vasculopathy, and reduced survival after cardiac transplantation. We hypothesized that endothelin antagonism during cardiac allograft storage would limit early endothelial dysfunction and improve myocardial performance after transplantation. Porcine orthotopic transplantations (n = 16) were performed after 6 hours of ischemic storage. Intermittent donor blood perfusion (control, n = 8) was compared with donor blood perfusion enhanced with 100 micromol/L of an endothelin receptor blocker (n = 8). Left ventricular performance was assessed after caval occlusion with a Millar micromanometer and conductance catheter. Coronary endothelial function was assessed in vitro with a macrovascular tissue bath apparatus. Myocardial endothelin, tumor necrosis factor alpha, and transforming growth factor beta protein expression were determined. Oxidative stress was inferred on the basis of 8-isoprostane levels, and myocardial metabolism was inferred on the basis of the extraction or production of oxygen, acid, and lactate by the heart. Endothelial function was diminished 48 hours after transplantation but not earlier. Endothelin receptor blocker treatment during preservation limited coronary endothelial dysfunction 48 hours after reperfusion ( P = .001). Weaning from cardiopulmonary bypass and left ventricular performance after transplantation was improved in endothelin receptor blocker-treated hearts (P = .02). Myocardial endothelin expression was equivalent in both groups and increased during reperfusion after transplantation (P = .001). Tumor necrosis factor alpha levels decreased with endothelin receptor blocker treatment (P = .02), whereas transforming growth factor beta levels did not change (P = .86). 8-Isoprostane, oxygen, acid, and lactate levels were similar, suggesting that oxidative stress and metabolism were not important mechanisms of benefit. Endothelin accumulates during allograft storage and contributes to endothelial and myocardial dysfunction after transplantation. Endothelin blockade during allograft preservation limits endothelial injury and enhances ventricular recovery after transplantation.

Addition of aprotinin to organ preservation solutions decreases lung reperfusion injury

Background. Organ preservation injury is associated with endothelial cell damage, destabilization of mitochondrial and cell membranes, and the release of proteolytic enzymes. In addition to its well-known clinical effect of reducing perioperative blood loss, aprotinin has antiproteolytic and membrane-stabilizing properties. We hypothesized that adding aprotinin to Euro-Collins (EC) and University of Wisconsin (UW) solutions would decrease preservation injury in cultured endothelial cells and a whole organ rat lung model. Methods. Bovine aortic endothelial cells were cultured and stored in the respective solution at 4°C for 12 or 48 hours. Endothelial cell viability after storage was assessed by dimethylthiazole tetrazolium cytotoxicity assay. In the whole organ model, rat lungs were isolated, flushed with the respective solution, and stored at 4°C for 6 or 12 hours. The lungs were ventilated with 100% O 2 and reperfused with fresh blood. Alveolar–arterial O 2 difference, O 2 tension, capillary filtration coefficient, and compliance were determined. Results. Endothelial cell viability was optimized with the addition of aprotinin to EC and UW at a dose of 150 KIU/mL (0.02 mg/mL). In the isolated perfused lung model, after 6 hours of ischemic storage, aprotinin-enhanced (100 KIU/mL [0.014 mg/mL]) EC and UW decreased alveolar–arterial O 2 difference, increased O 2 tension, and decreased capillary filtration coefficient compared with EC and UW alone. After 12 hours of ischemic storage, aprotinin-enhanced EC and UW decreased alveolar–arterial O 2 difference, increased O 2 tension, decreased capillary filtration coefficient, and increased compliance compared with EC and UW alone. Conclusions. The addition of aprotinin to EC and UW solutions increases endothelial cell viability in hypoxic cold storage conditions. In terms of whole organ function, aprotinin improves lung preservation as demonstrated by increased oxygenation and compliance, and decreased capillary permeability. This study is clinically applicable as there is already extensive experience with the use of aprotinin in heart and lung transplant recipients, in addition to its routine use in conventional cardiac operations.

Addition Of A Mast Cell Stabilizing Compound To Organ Preservation Solutions Decreases Lung Reperfusion Injury

Objective: Research in lung transplant preservation has generally focused on free radicals and enzyme release from neutrophils, parenchymal cells, macrophages, and endothelium. The lung has a large resident population of mast cells that, when activated, release potent inflammatory mediators. We hypothesized that adding an inhibitor of mast cell degranulation, lodoxamide tromethamine (10 μmol/L), to Euro-Collins and University of Wisconsin preservation solutions, would decrease lung preservation injury. Methods: Rat lungs were isolated, flushed with the respective solution, and stored at 4° C for 6 or 12 hours. The lungs were reperfused with fresh blood and ventilated with 100% oxygen. Alveolar-arterial oxygen difference, oxygen tension, capillary filtration coefficient, and compliance were determined. Results: After 6 hours of ischemic storage: lodoxamide tromethamine–enhanced Euro-Collins solution decreased alveolar-arterial oxygen difference from 539 to 457 ( p = 0.004), increased oxygen tension from 119 to 205 mm Hg ( p = 0.006), and decreased capillary filtration coefficient from 3.9 to 2.0 ( p < 0.001); lodoxamide tromethamine–enhanced University of Wisconsin solution decreased alveolar-arterial oxygen difference from 546 to 317 ( p < 0.001), increased oxygen tension from 166 to 335 mm Hg ( p < 0.001), and decreased capillary filtration coefficient from 3.0 to 1.7 ( p < 0.001). After 12 hours of ischemic storage, lodoxamide tromethamine–enhanced Euro-Collins solution decreased alveolar-arterial oxygen difference from 588 to 485 ( p < 0.001), increased oxygen tension from 100 to 161 mm Hg ( p = 0.012), decreased capillary filtration coefficient from 6.2 to 2.6 ( p < 0.001), and increased compliance from 0.12 to 0.21 ( p < 0.001); lodoxamide tromethamine–enhanced University of Wisconsin solution decreased alveolar-arterial oxygen difference from 478 to 322 ( p < 0.001), increased oxygen tension from 214 to 335 mm Hg ( p < 0.001), decreased capillary filtration constant from 4.2 to 2.0 ( p < 0.001), and increased compliance from 0.20 to 0.25 ( p < 0.001). Conclusions: Addition of lodoxamide tromethamine to Euro-Collins or University of Wisconsin solution results in a marked decrease in lung reperfusion injury as demonstrated by increased oxygenation, decreased microvascular permeability, and increased compliance. These results are relevant as Euro-Collins and University of Wisconsin solutions are the most common clinically used lung preservation solutions. This study also highlights the deleterious role of resident mast cells in preservation injury. (J Thorac Cardiovasc Surg 1998;115:631-7)