Murakami K, Abe T, Miyazawa M, Yamaguchi M, Masuda T, Matsuura T, Nagamori S, Takeuchi K, Abe K, Kyogoku M
Department of Pathology, Tohoku University School of Medicine, Sendai, Japan.
Lab Invest. 1995 Jun;72(6):731-9.
Thus far, human hepatic Ito (fat-storing) cell lines have not been established. Therefore, functional characteristics of Ito cells have not been fully investigated.
We established a new cell line, LI90, that exhibited characteristics compatible with those of Ito cells from a human hepatic mesenchymal tumor. LI90 cells were examined with phase-contrast microscopy, immunohistochemistry, and cytogenetics, and their vitamin A-storing activity was analyzed. To obtain a marker specific for Ito cells for immunohistochemical analyses, we raised mAb against LI90 cells and clarified the molecular nature of the Ag recognized with the new Ab using an expression cloning approach.
LI90 cells showed polygonal shape and had well developed alpha-smooth muscle actin filaments in their cytoplasm. In an overconfluent culture condition, LI90 cells aggregated to form a typical hills-and-valleys structure, LI90 cells produced various connective tissue components, such as collagen types I, III, IV, V, and VI, laminin, and fibronectin. In culture media containing vitamin A, LI90 cells formed many fat droplets in their cytoplasm, and fluorescence characteristic of vitamin A was observed in the droplets. By immunizing mice with LI90 cells, three separate mAb specifically reacting with Ito cells in human liver sections were established, and the Ag recognized with all three Ab were identified as extracellular matrix tenascin.
The above-described morphologic and functional characteristics, including vitamin A-storage and biosynthesis of tenascin, are compatible with those of Ito cells. Therefore, LI90 cells will be useful for in vitro studies of functions of human Ito cells.
迄今为止，尚未建立人肝伊托（贮脂）细胞系。因此，伊托细胞的功能特性尚未得到充分研究。
我们建立了一种新的细胞系LI90，其表现出与源自人肝间充质肿瘤的伊托细胞相符的特性。利用相差显微镜、免疫组织化学和细胞遗传学方法对LI90细胞进行检测，并分析其维生素A储存活性。为了获得用于免疫组织化学分析的伊托细胞特异性标志物，我们制备了针对LI90细胞的单克隆抗体，并采用表达克隆方法阐明了该新型抗体所识别抗原的分子性质。
LI90细胞呈多边形，细胞质中α-平滑肌肌动蛋白丝发育良好。在过度汇合的培养条件下，LI90细胞聚集形成典型的峰谷结构。LI90细胞产生多种结缔组织成分，如I、III、IV、V和VI型胶原、层粘连蛋白和纤连蛋白。在含有维生素A的培养基中，LI90细胞的细胞质中形成许多脂滴，并且在脂滴中观察到维生素A的荧光特征。通过用LI90细胞免疫小鼠，建立了三种分别与人肝切片中的伊托细胞特异性反应的单克隆抗体，并且所有这三种抗体所识别的抗原被鉴定为细胞外基质腱生蛋白。
上述形态学和功能特性，包括维生素A储存和腱生蛋白的生物合成，与伊托细胞的特性相符。因此，LI90细胞将有助于对人伊托细胞功能进行体外研究。
