Department of Internal Medicine-Nephrology, Leiden University Medical Center, Leiden, The Netherlands
Einthoven Laboratory of Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, The Netherlands.
J Am Soc Nephrol. 2020 May;31(5):921-929. doi: 10.1681/ASN.2019060573.
The utility of kidney organoids in regenerative medicine will rely on the functionality of the glomerular and tubular structures in these tissues. Recent studies have demonstrated the vascularization and subsequent maturation of human pluripotent stem cell-derived kidney organoids after renal subcapsular transplantation. This raises the question of whether the glomeruli also become functional upon transplantation.
We transplanted kidney organoids under the renal capsule of the left kidney in immunodeficient mice followed by the implantation of a titanium imaging window on top of the kidney organoid. To assess glomerular function in the transplanted human pluripotent stem cell-derived kidney tissue 1, 2, and 3 weeks after transplantation, we applied high-resolution intravital multiphoton imaging through the imaging window during intravenous infusion of fluorescently labeled low and high molecular mass dextran molecules or albumin.
After vascularization, glomerular structures in the organoid displayed dextran and albumin size selectivity across their glomerular filtration barrier. We also observed evidence of proximal tubular dextran reuptake.
Our results demonstrate that human pluripotent stem cell-derived glomeruli can develop an appropriate barrier function and discriminate between molecules of varying size. These characteristics together with tubular presence of low molecular mass dextran provide clear evidence of functional filtration. This approach to visualizing glomerular filtration function will be instrumental for translation of organoid technology for clinical applications as well as for disease modeling.
肾脏类器官在再生医学中的应用将依赖于这些组织中肾小球和肾小管结构的功能。最近的研究表明，在肾被膜下移植后，人类多能干细胞衍生的肾脏类器官会发生血管化，并随后成熟。这就提出了一个问题，即移植后肾小球是否也具有功能。
我们将肾脏类器官移植到免疫缺陷小鼠左肾的肾被膜下，然后在类器官上方植入钛制成像窗口。为了评估移植后 1、2、3 周的人类多能干细胞衍生肾脏组织中的肾小球功能，我们通过成像窗口在静脉内输注荧光标记的低和高分子质量葡聚糖分子或白蛋白时进行高分辨率活体多光子成像。
在血管化后，类器官中的肾小球结构表现出穿过其肾小球滤过屏障的葡聚糖和白蛋白大小选择性。我们还观察到近端肾小管葡聚糖重吸收的证据。
我们的结果表明，人类多能干细胞衍生的肾小球可以发展出适当的屏障功能，并区分不同大小的分子。这些特征以及肾小管中存在低分子质量葡聚糖为功能性过滤提供了明确的证据。这种可视化肾小球滤过功能的方法对于将类器官技术转化为临床应用以及疾病建模将是非常重要的。
