Expansion of human iPSC-derived ureteric bud organoids with repeated branching potential [DiI-VLDL]. Expansion of human iPSC-derived ureteric bud organoids with repeated branching potential [DiI-VLDL]

Ureteric bud (UB) is the embryonic kidney progenitor tissue that gives rise to the collecting duct and lower urinary tract. UB-like structures generated from human pluripotent stem cells by previously reported methods show limited developmental ability and limited branching. Here we report a new method to generate UB organoids that possess epithelial polarity and tubular lumen and repeat branching morphogenesis. We also succeeded in monitoring UB tip cells by utilizing the ability of tip cells to uptake very-low-density lipoprotein, cryopreserving UB progenitor cells and expanding UB tip cells that can reconstitute the organoids and differentiate into collecting duct progenitors. Moreover, we successfully reproduced some phenotypes of multicystic dysplastic kidney (MCDK) using the UB organoids. These methods will help elucidate the developmental mechanisms of UB branching and develop a selective differentiation method for collecting duct cells, contributing to the creation of disease models for congenital renal abnormalities. Overall design: mRNA profiles of DiI+ and DiI- cells of induced UB organoids

输尿管芽（Ureteric bud, UB）是胚胎期的肾脏祖细胞组织，可发育形成集合管与下尿路。此前已有研究通过已报道的方法从人多能干细胞中诱导生成UB样结构，但这类结构的发育潜能与分支能力均存在局限。本研究报道了一种全新的方法，可生成具备上皮极性与管状管腔、且可反复进行分支形态发生的UB类器官。我们还利用UB尖端细胞摄取极低密度脂蛋白的特性，成功实现了对UB尖端细胞的追踪监测；同时完成了UB祖细胞的冷冻保存，以及可重构类器官并分化为集合管祖细胞的UB尖端细胞的扩增培养。此外，本研究借助UB类器官成功复现了多囊性发育不良肾（Multicystic dysplastic kidney, MCDK）的部分病理表型。这些方法将有助于阐明UB分支的发育机制，并建立集合管细胞的定向分化方法，为先天性肾脏异常相关疾病模型的构建提供重要支撑。实验整体设计：诱导型UB类器官的DiI阳性与DiI阴性细胞的mRNA转录谱分析。