Guangdong Key Lab of Medical Electronic Instruments and Polymer Materials Products, National Engineering Research Center for Healthcare Devices, Guangdong Institute of Medical Instruments, Guangdong Academy of Sciences, Guangzhou, 510550, China.
Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Tissue Eng Regen Med. 2021 Apr;18(2):217-224. doi: 10.1007/s13770-020-00297-x. Epub 2021 Jan 30.
Ballooned hepatocytes (BH) are a key histological hallmark of nonalcoholic steatohepatitis (NASH), yet their consequences for liver-specific functions are unknown.
In our previous study, an experimental model of human induced-BHs (iBH) has been successfully developed based on cell sheet technology. This study aimed to determine the functions of iBHs in the primary human hepatocyte/normal human dermal fibroblast (PHH/NHDF) co-culture cell sheets. Normal hepatocytes in the PHH/3T3-J2 co-culture cell sheets were set as a control, since 3T3-J2 murine embryonic fibroblasts have exhibited previously long term maintenance of PHH functions.
It was found that, albumin secretion was not affected in iBHs, but urea synthesis as well as cytochrome P450 enzyme (CYP) activities including CYP1A2 and CYP3A4, were significantly reduced in iBHs. Besides, loss of bile canaliculi was observed in iBHs. These findings are consistent with clinical studies of human NASH. In addition, PHH/NHDF cell sheets demonstrated two fold higher TGF-β1 secretion compared with PHH/3T3-J2 cell sheets. Furthermore, treatment with a TGF-β inhibitor and a semi-synthetic bile acid analogue (obeticholic acid, phase 3 trial of NASH therapy) ameliorated the histological appearance of established iBHs.
In summary, this study demonstrates the priority of iBHs in recapitulating not only histology but also clinically relevant hepatic dysfunctions in human NASH and suggests TGF-β and bile acid related signal pathway may play important roles in the formation of iBHs.
气球样肝细胞（BH）是非酒精性脂肪性肝炎（NASH）的一个关键组织学特征，但它们对肝脏特异性功能的影响尚不清楚。
在我们之前的研究中，已经基于细胞片技术成功地建立了人诱导 BH（iBH）的实验模型。本研究旨在确定 iBH 在原代人肝细胞/正常人类真皮成纤维细胞（PHH/NHDF）共培养细胞片中的功能。PHH/3T3-J2 共培养细胞片中的正常肝细胞被设置为对照，因为 3T3-J2 鼠胚胎成纤维细胞先前已表现出对 PHH 功能的长期维持。
研究发现，iBH 中的白蛋白分泌不受影响，但尿素合成以及细胞色素 P450 酶（CYP）活性，包括 CYP1A2 和 CYP3A4，在 iBH 中显著降低。此外，还观察到 iBH 中胆小管的丧失。这些发现与人类 NASH 的临床研究一致。此外，与 PHH/3T3-J2 细胞片相比，PHH/NHDF 细胞片显示 TGF-β1 分泌增加了两倍。此外，用 TGF-β 抑制剂和半合成胆汁酸类似物（奥贝胆酸，NASH 治疗的 3 期试验）治疗可改善已建立的 iBH 的组织学外观。
总之，本研究表明 iBH 不仅在重现组织学方面具有优先性，而且在人类 NASH 中也具有临床相关的肝功能障碍，提示 TGF-β 和胆汁酸相关信号通路可能在 iBH 的形成中发挥重要作用。
