Department of Chemical System Engineering, University of Tokyo, Tokyo, Japan.
Institute of Industrial Science, University of Tokyo, Tokyo, Japan.
Biotechnol Bioeng. 2024 Apr;121(4):1435-1452. doi: 10.1002/bit.28653. Epub 2024 Jan 7.
Hepatic physiology depends on the liver's complex structural composition which among others, provides high oxygen supply rates, locally differential oxygen tension, endothelial paracrine signaling, as well as residual hemodynamic shear stress to resident hepatocytes. While functional improvements were shown by implementing these factors into hepatic culture systems, direct cause-effect relationships are often not well characterized-obfuscating their individual contribution in more complex microphysiological systems. By comparing increasingly complex hepatic in vitro culture systems that gradually implement these parameters, we investigate the influence of the cellular microenvironment to overall hepatic functionality in pharmacological applications. Here, hepatocytes were modulated in terms of oxygen tension and supplementation, endothelial coculture, and exposure to fluid shear stress delineated from oxygen influx. Results from transcriptomic and metabolomic evaluation indicate that particularly oxygen supply rates are critical to enhance cellular functionality-with cellular drug metabolism remaining comparable to physiological conditions after prolonged static culture. Endothelial signaling was found to be a major contributor to differential phenotype formation known as metabolic zonation, indicated by WNT pathway activity. Lastly, oxygen-delineated shear stress was identified to direct cellular fate towards increased hepatic plasticity and regenerative phenotypes at the cost of drug metabolic functionality - in line with regenerative effects observed in vivo. With these results, we provide a systematic evaluation of critical parameters and their impact in hepatic systems. Given their adherence to physiological effects in vivo, this highlights the importance of their implementation in biomimetic devices, such as organ-on-a-chip systems. Considering recent advances in basic liver biology, direct translation of physiological structures into in vitro models is a promising strategy to expand the capabilities of pharmacological models.
肝脏生理学依赖于肝脏复杂的结构组成，其中包括提供高氧气供应率、局部差异氧气张力、内皮旁分泌信号传递以及残余血液动力学切应力给驻留肝细胞。虽然通过将这些因素引入肝脏培养系统已经显示出功能上的改善，但直接的因果关系通常没有很好地表征出来，这使得它们在更复杂的微生理系统中的单独贡献变得模糊不清。通过比较逐渐实现这些参数的越来越复杂的肝脏体外培养系统，我们研究了细胞微环境对药理学应用中整体肝脏功能的影响。在这里，根据氧气张力和补充、内皮共培养以及与氧气流入相关的流体切应力暴露情况来调节肝细胞。转录组学和代谢组学评估的结果表明，特别是氧气供应率对于增强细胞功能至关重要——在长时间静态培养后，细胞药物代谢仍然与生理条件相当。内皮信号传递被发现是形成代谢分区（称为代谢分区）的主要因素，这表明 WNT 途径活性。最后，氧气界定的切应力被确定为以增加肝脏可塑性和再生表型为导向的细胞命运——这与体内观察到的再生效应一致。有了这些结果，我们对肝脏系统中的关键参数及其影响进行了系统评估。鉴于它们与体内生理效应的一致性，这突出了它们在仿生设备（如器官芯片系统）中的实施的重要性。考虑到基础肝脏生物学的最新进展，将生理结构直接转化为体外模型是扩展药理学模型功能的一种有前途的策略。
