Erasmus MC Transplant Institute, Department of Internal Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
Department of Developmental Biology and iPS Core Facility, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
Stem Cells. 2022 Jun 22;40(6):577-591. doi: 10.1093/stmcls/sxac009.
Induced pluripotent stem cell (iPSC)-derived kidney organoids are a potential tool for the regeneration of kidney tissue. They represent an early stage of nephrogenesis and have been shown to successfsully vascularize and mature further in vivo. However, there are concerns regarding the long-term safety and stability of iPSC derivatives. Specifically, the potential for tumorigenesis may impede the road to clinical application. To study safety and stability of kidney organoids, we analyzed their potential for malignant transformation in a teratoma assay and following long-term subcutaneous implantation in an immune-deficient mouse model. We did not detect fully functional residual iPSCs in the kidney organoids as analyzed by gene expression analysis, single-cell sequencing and immunohistochemistry. Accordingly, kidney organoids failed to form teratoma. Upon long-term subcutaneous implantation of whole organoids in immunodeficient IL2Ry-/-RAG2-/- mice, we observed tumor formation in 5 out of 103 implanted kidney organoids. These tumors were composed of WT1+CD56+ immature blastemal cells and showed histological resemblance with Wilms tumor. No genetic changes were identified that contributed to the occurrence of tumorigenic cells within the kidney organoids. However, assessment of epigenetic changes revealed a unique cluster of differentially methylated genes that were also present in undifferentiated iPSCs. We discovered that kidney organoids have the capacity to form tumors upon long-term implantation. The presence of epigenetic modifications combined with the lack of environmental cues may have caused an arrest in terminal differentiation. Our results indicate that the safe implementation of kidney organoids should exclude the presence of pro-tumorigenic methylation in kidney organoids.
诱导多能干细胞（iPSC）衍生的肾类器官是肾脏组织再生的潜在工具。它们代表了肾发生的早期阶段，并且已被证明可以在体内成功地血管化和进一步成熟。然而，人们对 iPSC 衍生物的长期安全性和稳定性存在担忧。特别是，致瘤性的潜在风险可能会阻碍其向临床应用的发展。为了研究肾类器官的安全性和稳定性，我们在畸胎瘤测定中和在免疫缺陷小鼠模型中进行长期皮下植入后分析了它们发生恶性转化的潜力。通过基因表达分析、单细胞测序和免疫组织化学分析，我们没有检测到肾类器官中有完全功能的残留 iPSC。因此，肾类器官未能形成畸胎瘤。在免疫缺陷的 IL2Ry-/-RAG2-/-小鼠中进行整个类器官的长期皮下植入后，我们在 103 个植入的肾类器官中有 5 个观察到肿瘤形成。这些肿瘤由 WT1+CD56+不成熟胚细胞组成，在组织学上与肾母细胞瘤相似。在肾类器官内未发现导致致瘤性细胞发生的遗传变化。然而，对表观遗传变化的评估显示出一个独特的差异甲基化基因簇，这些基因也存在于未分化的 iPSC 中。我们发现，肾类器官在长期植入后有形成肿瘤的能力。表观遗传修饰的存在加上缺乏环境线索可能导致终末分化停滞。我们的结果表明，在安全实施肾类器官时，应排除肾类器官中存在致瘤性甲基化。
