Human-induced pluripotent stem cell (iPSC)-derived kidney organoids have the potential to advance studies to kidney development and disease. However, reproducible generation of kidney organoids is a challenge. A large variability in the percentage of nephron structures and the expression of kidney-specific genes was observed among organoids, showing no association with iPSC lines. To associate the quality of kidney organoid differentiation with predictive markers, a ranking system was developed based on the ratio of nephron structure determined by histological examination. Well-differentiated organoids were defined as organoids with >30% nephron structure and vice versa. Subsequently, correlations were made with expression profiles of iPSC markers, early kidney development markers, and fibrosis markers. Higher expression of sex-determining region Y-box 2 (SOX2) during differentiation was associated with poorly differentiated kidney organoid. Furthermore, early secretion of basic fibroblast growth factor (FGF2) predicted poorly differentiated kidney organoid. Of interest, whereas cadherin-1 (CDH1) expression in kidney organoids indicates distal tubules formation, onefold higher CDH1 expression in iPSC predicted poor differentiation. High expression of the stromal progenitor marker Forkhead Box D1 (FOXD1) and significantly increased TGFβ levels were found in well-differentiated kidney organoids. These early expression profiles could predict the outcome of kidney organoid formation. This study helps to improve the robustness of kidney organoid protocols.

中文翻译：

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用于产生分化良好的人类诱导的多能干细胞衍生的肾脏类器官的预测标志物的鉴定

人类诱导的多能干细胞 (iPSC) 衍生的肾脏类器官具有推动肾脏发育和疾病研究的潜力。然而，肾脏类器官的可重复生成是一个挑战。在类器官中观察到肾单位结构百分比和肾脏特异性基因表达的巨大差异，显示与 iPSC 系无关。为了将肾脏类器官分化的质量与预测标志物联系起来，根据组织学检查确定的肾单位结构的比例开发了一个排名系统。分化良好的类器官被定义为具有>30% 肾单位结构的类器官，反之亦然。随后，与 iPSC 标志物、早期肾脏发育标志物和纤维化标志物的表达谱相关。分化过程中性别决定区 Y-box 2 (SOX2) 的高表达与低分化的肾脏类器官相关。此外，碱性成纤维细胞生长因子 (FGF2) 的早期分泌预示着低分化的肾脏类器官。有趣的是，虽然肾脏类器官中的 cadherin-1 (CDH1) 表达表明远端小管形成，但 iPSC 中 CDH1 表达高一倍预示着分化不良。在分化良好的肾脏类器官中发现了基质祖细胞标志物 Forkhead Box D1 (FOXD1) 的高表达和显着增加的 TGFβ 水平。这些早期表达谱可以预测肾脏类器官形成的结果。这项研究有助于提高肾脏类器官方案的稳健性。