Development of a prolonged warm ex vivo perfusion model for kidneys donated after cardiac death.

PURPOSE: Ex vivo perfusion of marginal kidney grafts offers the chance to expand the donor pool, but there is no current clinical standard for the prolonged warm perfusion of renal grafts. This exploratory pilot study seeks to identify a stable ex vivo kidney perfusion model that can support low intravascular resistance and preserve histologic architecture in a porcine donation after cardiac death (DCD) model. METHODS: 15 kidneys were preserved in 1 of 3 settings: normothermic whole blood (NT-WB), normothermic Steen Solution™ (XVIVO Perfusion) with whole blood (NT-Steen/WB), or subnormothermic Steen Solution™ at 21°C (SNT-Steen). Kidneys were primarily assessed using hemodynamic parameters and histologic analysis. RESULTS: NT-WB perfusion resulted in high vascular resistance and glomerular necrosis. NT-Steen/WB and SNT-Steen resistance ranged between 0.18-0.45 mmHg/mL per minute and 0.25-0.53 mmHg/mL per minute, respectively, enabling stable perfusion for up to 24 hours. NT-Steen/WB demonstrated tubular and glomerular necrosis, while the histologic architecture of SNT-Steen was preserved with the exception of numerous proteinaceous casts. CONCLUSIONS: Our results suggest that ex vivo kidney perfusion with Steen Solution™ at 21°C supports low and stable vascular resistance and provides adequate histologic preservation during 24-hour perfusion.

Role of vasodilation during normothermic machine perfusion of DCD porcine livers.

INTRODUCTION: Normothermic machine perfusion (NMP) of the liver is a promising preservation modality that holds the potential to better preserve and even repair marginal grafts. In spite of several literature studies showing the benefits of NMP over cold storage, there is paucity of data regarding the mechanisms involved in the optimization of the microcirculation during preservation of these organs. We present our data on the impact of different vasodilators on DCD porcine livers preserved with NMP. MATERIALS AND METHODS: Livers from 15 female Yorkshire pigs (30-40 kg) were subjected to 60 min of WIT followed by 10 h of NMP. Group PC (n = 5) received a prostacyclin analog (epoprostenol sodium) and the AD group (n = 5) received adenosine, whereas group WV (n = 5) was perfused without using any vasodilator. Liver function was assessed by measuring, liver enzyme levels, bile production rate, and histological analysis. RESULTS: At the end of perfusion, the PC group showed significantly lower AST (583 ± 62 vs. 2471 ± 745 and 2547 ± 690 IU/dl), ALT (41 ± 3 vs. 143 ± 28 and 111 ± 25 IU/dl) and LDH (840 ± 85 vs. 2756 ± 408 and 4153 ± 1569 IU/dl) levels compared to the AD and WV groups respectively (p<0.05). Bile production was significantly higher in the PC group compared to the AD group and WV, respectively (95 ± 9 vs. 37 ± 10 and 45 ± 18ml) (p<0.05). Histological samples of the PC group showed preserved hepatic architecture while those of the AD group and WV showed sinusoidal dilatation, architectural distortion, and profuse intraparenchymal hemorrhage. CONCLUSIONS: Maintenance of optimal microcirculatory homeostasis using proper vasodilators is a key factor in NMP of DCD livers.