Department of Urology, University of Florida, 1600 SW Archer Road, P.O. Box 100247, Gainesville, FL, 32610-0247, USA.
Division of Urology, Department of Surgery, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, USA.
Urolithiasis. 2022 Jun;50(3):239-247. doi: 10.1007/s00240-022-01322-5. Epub 2022 Mar 16.
Existing animal models of renal oxalate excretion utilize either gut or peritoneal cavity for oxalate absorption. Ex vivo renal perfusion is an established tool for graft preservation. We sought to repurpose this concept to study the early pathogenesis of urinary lithiasis. Juvenile female Yorkshire porcine kidneys were removed laparoscopically and placed on an ex vivo cardiopulmonary bypass circuit utilizing whole-blood based perfusate. Pre-defined goals were identified for each attempt (n = 5) with plans to increase physiologic model complexity. Tissue perfusion and oxygenation were monitored by serial perfusate iSTAT testing. Once steady urine production was achieved, aqueous oxalate was injected into the perfusate. Renal outcomes were assessed by histology and blood/urinary assays. After demonstrating proof-of-concept in early trials, normothermic (37 °C) ex vivo whole-blood perfusion with Steen Solution™ was performed exceeding three hours at physiologic mean arterial pressures. Circuit parameters remained in the physiologic range for electrolytes, temperature, mean arterial pressure, lactate, and pH. Urine was produced in three experiments. Urinary filtrate demonstrated consistently higher urine creatinine compared to perfusate, and arterial perfusate oxalate boluses lead to urinary oxalate spikes followed by continuous oxalate clearance. Histopathologic analysis with H&E and Pizzolato's method staining demonstrated formation of calcium oxalate crystals. In light of these promising metabolite clearances, ex vivo porcine renal perfusion appears to be a feasible alternative to study oxalate excretion. Longer validation studies are necessary to establish this technique as a model for kidney stone pathogenesis.
现有的肾脏草酸排泄动物模型利用肠道或腹腔进行草酸吸收。离体肾脏灌流是一种用于保存移植物的成熟工具。我们试图重新利用这一概念来研究尿石症的早期发病机制。通过腹腔镜手术切除幼年雌性约克夏猪的肾脏，并将其置于使用全血为基础的灌流液的离体心肺旁路循环中。为每次尝试（n=5）确定了明确的目标，并计划增加生理模型的复杂性。通过连续的灌流 iSTAT 测试监测组织灌注和氧合。一旦达到稳定的尿液生成，就将草酸水溶液注入灌流液中。通过组织学和血液/尿液检测评估肾脏结局。在早期试验中证明了概念验证后，在 37°C 的常温下进行 Steen SolutionTM 全血离体灌流，在生理平均动脉压下超过三个小时。电解质、温度、平均动脉压、乳酸和 pH 值的回路参数保持在生理范围内。在三个实验中产生了尿液。尿滤过液的尿肌酐始终高于灌流液，动脉灌流草酸弹丸注射会导致尿草酸峰值，随后持续清除草酸。H&E 和 Pizzolato 染色的组织病理学分析显示形成了草酸钙晶体。鉴于这些有希望的代谢物清除率，离体猪肾脏灌流似乎是研究草酸排泄的可行替代方法。需要进行更长时间的验证研究，以确立该技术作为肾结石发病机制模型的地位。
