Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250033, China.
Department of Emergency Surgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230036, China.
Curr Stem Cell Res Ther. 2023;18(4):551-559. doi: 10.2174/1574888X17666220818101503.
Human pluripotent stem cell (hPSC)-derived kidney organoids may contribute to disease modeling and the generation of kidney replacement tissues. However, the realization of such applications requires the induction of hPSCs into functional mature organoids. One of the key questions for this process is whether a specific vascular system exists for nephrogenesis. Our previous study showed that short-term (2 weeks) implantation of hPSC-derived organoids below the kidney capsules of unilaterally nephrectomized and immunodeficient mice resulted in the enlargement of organoids and production of vascular cells, although signs of maturation were lacking.
Organoids were induced for 15 days in vitro and then grafted below kidney capsules of the same unilaterally nephrectomized immunodeficient mouse model to examine whether medium-term (4 weeks) implantation could improve organoid maturation and vascularization, as evaluated by immunofluorescence and transmission electron microscopy.
We demonstrated that after 2-4 weeks of implantation, renal organoids formed host-derived vascularization and matured without any exogenous vascular endothelial growth factor. Glomerular filtration barrier maturation was evidenced by glomerular basement membrane deposition, perforated glomerular endothelial cell development, and apical, basal podocyte polarization. A polarized monolayer epithelium and extensive brush border were also observed for tubular epithelial cells.
Our results indicate that the in vivo microenvironment is important for the maturation of human kidney organoids. Stromal expansion and a reduction of nephron structures were observed following longer-term (12 weeks) implantation, suggesting effects on off-target cells during the induction process. Accordingly, induction efficiency and transplantation models should be improved in the future.
人类多能干细胞（hPSC）衍生的肾类器官可能有助于疾病建模和产生肾替代组织。然而，要实现这些应用，需要将 hPSC 诱导为功能性成熟的类器官。这个过程的关键问题之一是是否存在特定的血管系统用于肾发生。我们之前的研究表明，将 hPSC 衍生的类器官短期（2 周）植入单侧肾切除和免疫缺陷小鼠的肾囊下，会导致类器官增大和血管细胞产生，尽管缺乏成熟的迹象。
类器官在体外诱导 15 天，然后移植到同一单侧肾切除免疫缺陷小鼠模型的肾囊下，以评估中期（4 周）植入是否可以改善类器官的成熟和血管化，通过免疫荧光和透射电子显微镜进行评估。
我们证明，在植入 2-4 周后，肾类器官形成了宿主来源的血管化，并在没有任何外源性血管内皮生长因子的情况下成熟。肾小球滤过屏障的成熟表现在肾小球基底膜沉积、穿孔的肾小球内皮细胞发育以及顶端和基底足细胞的极化。管状上皮细胞也观察到极化的单层上皮和广泛的刷状缘。
我们的结果表明，体内微环境对人类肾类器官的成熟很重要。在更长时间（12 周）的植入后观察到基质扩张和肾单位结构减少，这表明在诱导过程中对非靶细胞有影响。因此，未来应改进诱导效率和移植模型。
