Effect of vaporized perfluorocarbon on oxidative stress during the cold ischemia phase of lung graft preservation.

Liquid perfluorocarbon (PFC) instillation has been studied experimentally as an adjuvant therapy in the preservation of lung grafts during cold ischemia. The objective of this study was to evaluate whether vaporized PFC is also protective of lung grafts at different cold ischemia times. We performed histological analysis of and measured oxidative stress in the lungs of animals that received only preservation solution with low-potassium dextran (LPD) or vaporized PFC together with LPD. We conclude that vaporized PFC reduces the production of free radicals and the number of pulmonary structural changes resulting from cold ischemia.

Effect of vaporized perfluorocarbon on oxidative stress during the cold ischemia phase of lung graft preservation / Efeito do perfluorocarbono vaporizado sobre o estresse oxidativo no período de isquemia fria durante a preservação pulmonar

ABSTRACT Liquid perfluorocarbon (PFC) instillation has been studied experimentally as an adjuvant therapy in the preservation of lung grafts during cold ischemia. The objective of this study was to evaluate whether vaporized PFC is also protective of lung grafts at different cold ischemia times. We performed histological analysis of and measured oxidative stress in the lungs of animals that received only preservation solution with low-potassium dextran (LPD) or vaporized PFC together with LPD. We conclude that vaporized PFC reduces the production of free radicals and the number of pulmonary structural changes resulting from cold ischemia.

RESUMO O perfluorocarbono (PFC) líquido tem sido estudado experimentalmente como uma substância adjuvante na preservação de enxertos pulmonares durante o período de isquemia fria. O objetivo deste estudo foi avaliar se o PFC vaporizado (e não instilado) também atuaria como protetor de enxertos pulmonares em diferentes tempos de isquemia fria. Realizamos análise histológica e dosamos o estresse oxidativo em pulmões de animais que receberam somente uma solução de preservação com low-potassium dextran (LPD, dextrana com baixa concentração de potássio) ou PFC vaporizado associado a LPD. Concluímos que o PFC vaporizado reduziu a produção de radicais livres e provocou menor número de alterações estruturais pulmonares decorrentes do período de isquemia fria que o uso de LPD isoladamente.

Protective effect of Ulva lactuca extract during hepatic cold preservation in rats.

Introduction In recent years, many marine resources have drew attention in the research for bio-active compounds to develop new drugs and health foods. (1) Marine algae are now considered as a rich source of antioxidants (2). It is known that seaweeds contain numerous bioactive substances that have the ability to lower cholesterol, reduce blood pressure, promote healthy digestion; and antioxidant activity (3). Natural antioxidants are interesting compounds due to their properties which help prevent oxidative stress (4), among other potentially beneficial actions. For instance, several biological effects have been attributed to flavonoids, such as anti-tumoral, anti-inflammatory, anti-ischemic and anti-aggregate plaquetary activities. These activities are believed to be in part related to the antioxidant properties of the compounds, namely in scavenging radical oxygen species (ROS). (5, 6) The cold ischemia constitute a situation of oxidative stress in touch with liberation of oxygenated radicals, these situations incited the researchers to find means for the improvement of the conservation of organs allowing to prolong the durations of the cold ischemia of certain organs (in particular the liver) with conservation of the maximum functional value. However, the constant efforts led by the teams of transplantation to develop transplants, the conservation of organs remains a problem to be resolved. (7) Conservation solution of organ appears as being a stemming to remedy the fatal effects of the ischemia-reperfusion. For our part, we think that seaweeds have not delivered their secrets and yet especially that the marine environment of the Tunisian coast still remains little exploited in spite of the big variety of the fauna and the flora of the coast. We envisage in this work, to study a sort of seaweed collected on the Tunisian quotation in the region of "Chott Meriem" (North West of Tunisia). The purpose of our work is to estimate the capacity of extracts stemming from the green seaweed Ulva lactuca to improve the conservation solution of organs against the hepatic effects of ischemia.

Pancreatic L-Glutamine Administration Protects Pig Islets From Cold Ischemic Injury and Increases Resistance Toward Inflammatory Mediators.

The isolation and transplantation of porcine islets represent a future option for the treatment of type 1 diabetic patients. Stringent product release criteria and limited availability of transgenic and specific pathogen-free pigs will essentially require processing of explanted pig pancreata in specialized, possibly remote isolation facilities, whereby pancreata are exposed to cold ischemia due to prolonged tissue transit time. In the present study we investigated whether pancreas oxygenation can be efficiently combined with an antioxidant strategy utilizing intraductal L-glutamine administration. Pig pancreata were intraductally perfused after retrieval and after cold storage in oxygen-precharged perfluorohexyloctane utilizing University of Wisconsin solution supplemented with (n = 16) or without (n = 14) 5 mmol/L L-glutamine. After isolation purified islets were subjected to extensive quality assessment. Islet recovery postpurification was significantly higher in glutamine-treated pancreata (77.0 ± 3.3% vs. 60.3 ± 6.0%, p < 0.05). Glutamine administration increased intraislet content of reduced glutathione (117.8 ± 16.5 vs. 15.9 ± 2.8 ng/ng protein, p < 0.001) associated with increased islet recovery after culture (65.8 ± 12.1% vs. 40.3 ± 11.7%, p < 0.05), enhanced glucose stimulation index (1.82 ± 0.16 vs. 1.38 ± 0.10, p < 0.05), and improved posttransplant function in diabetic nude mice (p < 0.05). Furthermore, intraductally administered glutamine increased pig islet resistance toward reactive oxygen species, nitric oxide, and high-dose proinflammatory cytokines. The present study demonstrates that quality and function of pig islets exposed to warm and cold ischemia can significantly be improved using intraductal l-glutamine administration. As the efficiency of the intraductal route may be inferior compared to intravascular administration further studies should aim on assessment of l-glutamine as supplement for pancreas perfusion during organ procurement.

Naked caspase 3 small interfering RNA is effective in cold preservation but not in autotransplantation of porcine kidneys.

BACKGROUND: Caspase 3 associated with apoptosis and inflammation plays a key role in ischemia-reperfusion injury. The efficacy of naked caspase 3 small interfering RNA (siRNA) has been proved in an isolated porcine kidney perfusion model but not in autotransplantation. MATERIALS AND METHODS: The left kidney was retrieved from mini pigs and infused with the University of Wisconsin solution with or without 0.3mg of caspase 3 siRNA into the renal artery with the renal artery and vein clamped for 24-h cold storage (CS). After right nephrectomy, the left kidney was autotransplanted into the right for 48 h without systemic treatment of siRNA. RESULTS: Fluorescent dye-labeled caspase 3 siRNA was visualized in the post-CS kidneys but was weakened after transplantation. The expression of caspase 3 messenger RNA and precursor was downregulated by siRNA in the post-CS kidneys. In the siRNA-preserved posttransplant kidneys, however, the caspase 3 messenger RNA and active subunit were upregulated with further decreased precursor but increased active caspase 3+ cells, apoptotic cells, and myeloperoxidase+ cells. Moreover, the renal tissue damage was aggravated by siRNA, whereas the renal function was not significantly changed. CONCLUSIONS: Naked caspase 3 siRNA administered into the kidney was effective in cold preservation but not enough to protect posttransplant kidneys, which might be because of systemic complementary responses overcoming local effects.

Reduction of chronic graft injury with a new HTK-based preservation solution in a murine heart transplantation model.

OBJECTIVE: Aim of this study was to evaluate a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution on chronic isograft injury in comparison to traditional HTK solution. METHODS: Hearts of C57BL/6J (H-2b) mice were stored for 15 h in 0-4 °C cold preservation solution and then transplanted heterotopically into C57BL/6J (H-2b) mice. Three groups were evaluated: HTK, the base solution of a new preservation solution and hearts without cold ischemia (control). Time to restoration of heartbeat was measured (re-beating time). Strength of the heartbeat was palpated daily and scored on a 4-level scale (palpation score). Animals were sacrificed after 60 days of observation (24 h for TGF-ß expression). The transplanted hearts were evaluated histologically for myocardial damage, vasculopathy and interstitial fibrosis. TGF-ß expression was assessed immunohistologically. All investigators were blinded to the groups. ANOVA and LSD post hoc test were used for statistical analysis. RESULTS: The re-beating time was significantly shorter in hearts stored in the new solution (10.3±2.6 min vs. HTK 14.2±4.1 min; p<0.05). The palpation score was significantly higher in hearts stored in the new solution (2.3±0.4 vs. HTK 1.6±0.5; p<0.01). Hearts stored in the new solution showed a lower myocardial injury score (1.8±0.2 vs. HTK 2.2±0.7), less interstitial fibrosis (4.8±1.9% vs. HTK 8.5±3.8%, p<0.05), less vasculopathy (14.7±6.9% vs. 22.0±23.2%; p=0.06) and lower TGF-ß1-expression (6.6±1.4% vs. HTK 12.0±4.6%). CONCLUSION: The new HTK-based solution reduces the chronic isograft injury. This protective effect is likely achieved through several modifications and supplements into the new solution like N-acetyl-L-histidine, glycine, alanine, arginine and sucrose.