Impact of hepatic perfusion on lobular and lobar distribution of test compound metabolism in rats

接受大范围肝切除术（(e)PHx）的患者术后出现肝功能障碍甚至肝功能衰竭的风险很高，特别是在先前存在肝脏疾病的情况下。我们的研究小组QuaLiPerF旨在通过系统医学方法，提高对健康、脂肪变性和再生肝脏手术后肝脏灌注与功能之间定量和空间关系的理解。本项目将重点评估灌注扰动和灌注损伤对肝功能丧失和恢复的影响。我们假设灌注的空间不均匀性与肝细胞在再生过程中的功能表现及其增殖相匹配。我们的目的是通过a)在小叶和大叶尺度上对肝脏灌注和脂肪变性的空间分辨量化，b)探索与肝细胞增殖相关的实验性化合物代谢能力和空间分布，来评估肝脏灌注对正常肝脏、脂肪变性肝脏和再生肝脏实验性化合物代谢的影响。为了达到这一目标，我们将在大鼠模型中使用三种不同的灌注扰动方法：肝脂肪变性、门静脉结扎和肝脏切除术，在多个尺度上研究肝脏灌注损伤。动物将接受肝脏血流动力学和微循环的详细评估，使用侧流暗场成像和光学传感器显示组织氧合。探查多个肝叶可显示肝脏灌注的异质性。测试复合代谢是用于评估肝功能的尺度跨越。我们将在应用五种不同的测试化合物后进行药代动力学研究。我们将通过测定相应的CYP酶活性、测定蛋白质和mRNA水平以及测定不同肝叶组织样本的区向表达来分析这些药物的代谢，以解释异质性。肝再生将在手术后立即评估，并在术后第一周内通过肝脏与体重的比率、体积和功能恢复以及肝细胞的增殖来评估。这些结果将与肝脏体积、灌注和功能的详细MRI评估进行比较。我们的结果将补充研究碳水化合物/脂质代谢和详细的基因表达分析。从而形成一个以肝脏灌注为功能的代谢控制评估的综合网络。所有的实验数据和相应的临床数据将作为集成计算模型的输入，用于空间分辨预测肝术后未来残肝的再生和功能恢复。因此，对(e)PHX患者的功能预测和风险分层将得到改善。

Patients subjected to extended liver resection ((e)PHx) have a high risk to experience postoperative liver dysfunction or even liver failure, especially in case of preexisting liver disease. Our research group QuaLiPerF aims to enhance the understanding of the quantitative and spatial relationship between hepatic perfusion and function in healthy, steatotic and regenerating livers after surgery using a systems medicine approach. This project will focus on assessing the impact of perfusion perturbation and perfusion impairment on loss and recovery of liver function. We hypothesize that spatial inhomogeneity of perfusion matches the functional performance of the hepatocytes and their proliferation during regeneration. It is our aim to assess the impact of hepatic perfusion on test compound metabolism in normal, steatotic and regenerating livers by a) spatially resolved quantification of hepatic perfusion and steatosis on the lobular and lobar scale,b) exploring the capacity and spatial distribution of test compound metabolism in relation to hepatocyte proliferation.To reach this goal, we are going to investigate liver perfusion impairments on multiple scales using three different approaches of perfusion perturbation in the rat model: hepatic steatosis, portal vein ligation, and liver resection. Animals will be subjected to detailed assessment of hepatic hemodynamics and microcirculation using side-stream dark field imaging and an optical sensor revealing the tissue oxygenation. Probing multiple liver lobes will reveal the heterogeneity of hepatic perfusion.Test compound metabolism is used for scale spanning assessment of hepatic function. We will perform pharmacokinetic studies after applying five different test compounds. We will analyze metabolism of these drugs by determination of the corresponding CYP enzyme activity, measurement of protein and mRNA levels and determination of zonal expression in tissue samples obtained from different liver lobes to account for heterogeneity. Liver regeneration will be assessed immediately after surgery and within the first postoperative week by addressing liver-to-body-weight ratios, volume and functional recovery as well as proliferation of hepatocytes.These results will be compared to detailed MRI assessment of liver volume, perfusion and function. Our results will be complementary to investigations of the carbohydrate/lipid metabolism and a detailed gene expression analysis. Thus, a comprehensive network of metabolic control assessment as a function of liver perfusion will be generated.All experimental data together with corresponding clinical data will serve as input for the integrated computational models needed for spatially resolved prediction of regeneration and functional recovery of the future liver remnant after liver surgery. As a result, prediction of function and risk stratification for patients undergoing (e)PHX will be improved.