Doi Kotaro, Kimura Hiroshi, Matsunaga Yukiko T, Fujii Teruo, Nangaku Masaomi
Institute of Industrial Science, The University of Tokyo, Tokyo, Japan.
Department of Mechanical Engineering, School of Engineering, Tokai University, Kanagawa, Japan.
Int J Nephrol Renovasc Dis. 2022 Mar 10;15:85-101. doi: 10.2147/IJNRD.S344725. eCollection 2022.
Glomerulopathy, characterized by a dysfunctional glomerular capillary wall, results in proteinuria, leading to end-stage renal failure and poor clinical outcomes, including renal death and increased overall mortality. Conventional glomerulopathy research, including drug discovery, has mostly relied on animal experiments because in-vitro glomerulus models, capable of evaluating functional selective permeability, was unavailable in conventional in-vitro cell culture systems. However, animal experiments have limitations, including time- and cost-consuming, multi-organ effects, unstable reproducibility, inter-species reliability, and the social situation in the EU and US, where animal experiments have been discouraged. Glomerulus-on-a-chip, a new in-vitro organ model, has recently been developed in the field of organ-on-a-chip research based on microfluidic device technology. In the glomerulus-on-a-chip, the podocytes and endothelial cells are co-cultured in a microfluidic device with physical stimuli that mimic the physiological environment to enhance cell function to construct a functional filtration barrier, which can be assessed by permeability assays using fluorescently labeled molecules including inulin and albumin. A combination of this glomerulus-on-a chip technology with the culture technology to induce podocytes and endothelial cells from the human pluripotent stem cells could provide an alternative organ model and solve the issue of animal experiments. Additionally, previous experiments have verified the difference in the leakage of albumin using differentiated podocytes derived from patients with Alport syndrome, such that it could be applied to intractable hereditary glomerulopathy models. In this review, we provide an overview of the features of the existing glomerulus-on-a-chip systems, focusing on how they can address selective permeability verification tests, and the challenges they involved. We finally discuss the future approaches that should be developed for solving those challenges and allow further improvement of glomerulus-on-a-chip technologies.
肾小球病以肾小球毛细血管壁功能失调为特征，会导致蛋白尿，进而引发终末期肾衰竭以及不良临床结局，包括肾死亡和总体死亡率上升。传统的肾小球病研究，包括药物研发，大多依赖动物实验，因为在传统的体外细胞培养系统中，缺乏能够评估功能选择性通透性的体外肾小球模型。然而，动物实验存在局限性，包括耗时、成本高、多器官效应、重复性不稳定、种间可靠性问题，以及在欧盟和美国不鼓励进行动物实验的社会环境。芯片上的肾小球是一种新的体外器官模型，最近在基于微流控设备技术的芯片上器官研究领域得到了发展。在芯片上的肾小球中，足细胞和内皮细胞在微流控设备中共同培养，并受到模拟生理环境的物理刺激以增强细胞功能，从而构建功能性滤过屏障，这可以通过使用包括菊粉和白蛋白在内的荧光标记分子进行通透性测定来评估。这种芯片上的肾小球技术与从人类多能干细胞诱导足细胞和内皮细胞的培养技术相结合，可以提供一种替代器官模型，并解决动物实验的问题。此外，先前的实验已经验证了使用来自Alport综合征患者的分化足细胞时白蛋白泄漏的差异，因此它可以应用于难治性遗传性肾小球病模型。在这篇综述中，我们概述了现有芯片上的肾小球系统的特点，重点关注它们如何进行选择性通透性验证测试以及所涉及的挑战。我们最后讨论了为解决这些挑战并进一步改进芯片上的肾小球技术而应开发的未来方法。
