Functional and morphological analysis of vascular endothelial cells and pericytes/smooth muscle cells in the hepatic porto-sinusoidal-hepatic venous system

肝脏的特点是低压循环系统和独特的血管结构。在这项研究中，我们研究了门窦肝静脉系统中血管内皮细胞和周细胞/平滑肌细胞的异质性。在小鼠肝蛋白a诱导的肝炎模型中，淋巴细胞粘附、转运和粘附分子（VCAM-1、e -选择素）的表达在小叶下静脉中最为突出，在肝窦和肝小静脉中表达中等，而在门静脉中可以忽略（Morikawa et al. 2000）。在同一模型中，肝小叶中间区止血最明显，门静脉周围区止血不明显（Miyazawa et al. 1998），提示肝小叶内窦状窦的异质性。在内皮素-1灌注大鼠实验中，门脉前小静脉远端段（长度为300 μm）血管周围平滑肌细胞明显收缩，而窦周围的星状细胞收缩可忽略不计，表明窦前段在调节肝脏微循环中起重要作用（Kaneda et al. 1998; Ekataksin and Kaneda 1999）。星状细胞具有不同于血管周围平滑肌细胞的特性。然而，它们经过转化并获得与后者细胞相同的一些特性。在人肝癌包膜中，星状细胞可能表达平滑肌肌动蛋白和肌球蛋白。本研究结果为了解肝脏的生理功能和肝脏疾病的发病机制提供了基础资料。

The liver is characterized by its low-pressure circulatory system and has a unique vascular architecture. In this study, we investigated the heterogeneity of vascular endothelial cells and pericytes/smooth muscle cells in the porto-sinusoidal-hepatic venous system.In a mouse model of hepatitis induced by concanavalin A administration, lymphocyte adherence, transmigration, and adhesion molecule (VCAM-1, E-selectin) expression were most prominent in the sublobular veins, moderate in the sinusoids and small hepatic veins, and negligible in the portal tract (Morikawa et al. 2000). In the same model, hemostasis was most striking in the intermediate zone of the liver lobule, and not obvious in the periportal zone (Miyazawa et al. 1998), indicating the intralobular heterogeneity of the sinusoids.In the experiment of endothelin-1 perfusion using rats, a distal segment of the preterminal portal venules (300 μm in length) showed a striking constriction of perivascular smooth muscle cells, while stellate cells around the sinusoid underwent negligible constriction, indicating that presinusoidal segments play important roles in the regulation of hepatic microcirculation (Kaneda et al. 1998 ; Ekataksin and Kaneda 1999). Stellate cells have distinct properties from perivascular smooth muscle cells. However, they undergo transformation and gain some properties common to the latter cells. In the capsule of human hepatocellular carcinoma, it is suggested that stellate cells may come to express smooth muscle actin and myosin.The present results provide basic data on intrahepatic vasculatures to understand the physiological function of the liver and pathogenesis of the hepatic disorders.