In vivoquantification of oxygen-free radical release in experimental pancreas transplantation

Abstract

Summary Reactive oxygen species (ROS) were drawn to the attention in the setting of organ transplantation when the ‘injury hypothesis’ postulated a link between oxidative stress and the activation of the innate immunity of the recipient. While the occurrence of ROS during organ transplantation is undoubted, their onset and magnitude remain largely unknown. We therefore measured ROS using a novel cyclic hydroxylamine spin probe CMH (1‐hydroxy‐3‐ methoxycarbonyl‐2,2,5,5‐tetramethylpyrrolidine) during syngeneic experimental pancreas transplantation in rats in vivo. Organs were subjected to two different cold preservation methods [University of Wisconsin preservation solution (UW) or normal saline] for 18 h. During the first 90 min of reperfusion, samples were collected and analysed using electron paramagnetic resonance signalling. Isolated blood‐free perfused organs (IPO) were used for comparison. Analysis showed that it is feasible to detect ROS using CMH spin probes. While IPO organs displayed a very early ROS release, there was no ROS increase in the UW preserved group compared to NaCl. These findings were in line with conventional markers of organ damage such as serum lactate, glucose, potassium as well as tissue ATP levels. CMH spin probes might become a useful tool for the in vivo animal testing of antioxidative substances in models of solid organ transplantation.

Islets of Langerhans Are Protected from Inflammatory Cell Recruitment during Reperfusion of Rat Pancreas Grafts

“…I/R-injury in pancreas grafts is characterized by oxidative stress-related microcirculatory disorders and inflammatory cell invasion [10,12] , ultimately mimicking the situation of acute necrotizing pancreatitis of native organs. Based on this feature, earlier studies focused mostly on microcirculatory alterations of the exocrine, rather than the endocrine part of the grafts [4,22,23] , although restitution of the endocrine function is the primary goal of pancreas transplantation.…”

“…Specific adhesion molecules (selectins, integrins, immunoglobulin superfamily), localized on the surface of leukocytes and the endothelium, are involved in these cellular interactions. Besides a network of hormones, chemokines and cytokines, their expression is initiated by free oxygen radicals, released immediately after reintroduction of molecular oxygen to the graft [10] . In parallel, increased macromolecular endothelial permeability allows protein extravasation and concomitant fluid shift to the extravascular space.…”

Blood Modulates the Kinetics of Reactive Oxygen Release in Pancreatic Ischemia-Reperfusion Injury

“…6 In contrast to the in vivo setting, in vitro, a single-pass perfusion with CMH was necessary to have constant availability of the spin label without any accumulation during the experiment, possibly leading to falsely high ROS levels. As we have shown in a previous set of experiments, CMH is renally eliminated, so in vivo no accumulation takes place.…”

Multifunctional ternary drug‐loaded electrospun scaffolds

“…The biological system has a proper balance between the formation and removal of the reactive oxygen species. Also, transplantation of organ and tissues has more success when stress oxidative is reduced by the administration of molecules with antioxidant activity . Although there are very few reports about devices and scaffolds loaded with antioxidants, some of them merit attention, e.g., those concerning mats of electrospun cellulose acetate fibers containing asiaticoside or curcumin, vitamin A acid or vitamin E, as well as polyesters like polycaprolactone and polylactide loaded with curcumin, and gallic acid, respectively.…”