9-cis-retinoic acid improves disease modelling in iPSC-derived liver organoids

Liver fibrosis majorly impacts global health, necessitating development of in vitro models to study disease mechanisms and develop drug therapies. Relevant models should at least include hepatocytes and hepatic stellate cells (HSCs) and ideally use three-dimensional cultures to mimic in vivo conditions. Induced pluripotent stem cells (iPSCs) allow patient-specific liver modelling, but current models based on iPSC-derived hepatocytes (iHepatocytes) and HSCs (iHSCs) still lack key functions. We developed organoids of iHepatocytes and iHSCs, and compared them to HepaRG and primary HSC organoids. RNA-sequencing analysis comparison of these cultures identified a potential role for the transcription factor RXRA in hepatocyte differentiation and HSC quiescence. Treating cells with the RXRA ligand 9-cis-retinoic acid (9CRA) promoted iHepatocyte metabolism and iHSC quiescence. In organoids, 9CRA enhanced fibrotic response to TGF-β and acetaminophen, highlighting its potential for refining iPSC-based liver fibrosis models to more faithfully replicate human drug-induced liver injury and fibrotic conditions.肝纤维化（Liver fibrosis）已对全球公共健康造成显著负面影响，亟需构建体外模型以研究疾病发病机制并开发药物治疗方案。合格的模型至少应包含肝细胞（hepatocytes）与肝星状细胞（hepatic stellate cells, HSCs），理想情况下需采用三维培养体系以模拟体内（in vivo）生理环境。诱导多能干细胞（iPSCs）可实现患者特异性肝脏建模，但当前基于诱导多能干细胞衍生肝细胞（iHepatocytes）与肝星状细胞（iHSCs）构建的模型仍缺乏关键生理功能。本研究构建了iHepatocytes与iHSCs类器官，并将其与HepaRG细胞系及原代肝星状细胞类器官进行对照分析。对上述培养体系的RNA测序（RNA-sequencing）分析显示，转录因子RXRA可能在肝细胞分化与肝星状细胞静息状态维持中发挥调控作用。使用RXRA配体9-顺式维甲酸（9-cis-retinoic acid, 9CRA）处理细胞后，可促进iHepatocytes的代谢功能并维持iHSCs的静息状态。在类器官模型中，9CRA可增强体系对转化生长因子-β（TGF-β）与对乙酰氨基酚的纤维化应答反应，这表明其可用于优化基于iPSCs的肝纤维化模型，使其更精准地复现人类药物性肝损伤与纤维化病理状态。