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

肝脏以其低压循环系统为特征，并具有独特的血管结构。在这项研究中，我们研究了门静脉-肝窦-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。在刀豆蛋白A诱导的小鼠肝炎模型中，淋巴细胞黏附、移行和黏附分子(VCAM-1，E-选择素)的表达在小叶下静脉最明显，在肝窦和小肝静脉中中等，在门静脉系统中可以忽略(Morikawa等人)。2000)。在同一模型中，止血最显著的是肝小叶的中间区，而不是门脉周围区(Miyazawa等人)。在大鼠实验中，门静脉前末端远端(长300μm)的一段血管周围的平滑肌细胞明显收缩，而肝窦周围的星状细胞的收缩可以忽略不计，这表明肝窦前段在调节肝脏微循环中起重要作用(Kaneda et al.1998年；Ekataksin和Kaneda 1999年)。星状细胞具有不同于血管周围平滑肌细胞的特性。然而，它们会经历转化，并获得后一种细胞的一些共同属性。在人肝细胞癌的包膜中，星状细胞可能表达平滑肌肌动蛋白和肌球蛋白，为了解肝脏的生理功能和肝病的发病机制提供了基础数据。

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.