Studying normal and cancer stem cells in the kidney using 3D organoids and genetic mouse models

Organoide aus adulten Mäusen sind vielversprechende Modelle für die Nierenforschung. Ihre Charakterisierung wurde jedoch nicht auf ein zufriedenstellendes Niveau gebracht. Hier habe ich ein langfristiges 3D-Maus-Organoid (Tubuloid)-Modell etabliert und charakterisiert, das die Erneuerung und die Reparatur sowie die Architektur und die Funktionalität der adulten tubulären Epithelien rekapituliert. In der Zukunft wird das Modell detaillierte Untersuchungen der Trajektorien selbsterneuernder Zellen sowohl zur teilweisen Wiederherstellung der Niere als auch zur malignen Transformation der Niere ermöglichen. Das klarzellige Nierenzellkarzinom (ccRCC) ist der häufigste und aggressivste Nierenkrebs. Die Inaktivierung des Tumorsuppressorgens Von Hippel-Lindau (VHL) ist der Haupttreiber des ccRCCs. Zuvor hatten wir die Hochregulation der Wnt- und Notch-Signalübertragung in den CXCR4+MET+CD44+-Krebsstammzellen (CSC) aus primären humanen ccRCC-Tumoren identifiziert. Das Blockieren von Wnt und Notch in von Patienten stammenden Xenotransplantaten, Organoiden und nicht-anhaftenden Sphären unter Verwendung von niedermolekularen Inhibitoren beeinträchtigte die Selbsterneuerung der CSC und das Tumorwachstum. Um CSC-gesteuertes humanes ccRCC in genetischen Mausmodellen nachzuahmen, begann ich mit der Erzeugung von zwei Doppelmausmutanten; β-Catenin-GOF; Notch-GOF und Vhl-LOF; β-Catenin-GOF. Sowohl die β-Catenin-GOF; Notch-GOF Mausmutante als auch die Vhl-LOF; β-Catenin-GOF Mausmutante entwickelten innerhalb einiger Monate schwere Krankheitssymptome. Überraschenderweise beobachtete ich weder Tumore oder Tumorvorläuferläsionen noch höhere Zellproliferationsraten in den mutierten Nieren. Weitere Analysen ergaben, dass die Mausmutanten Merkmale chronischer Nierenerkrankung (CKD) aufwiesen.Adult mouse organoids are promising models for kidney research. However, their characterization has not been pushed forward to a satisfying level. Here, I have generated and characterized a long-term 3D mouse organoid (tubuloid) model, which recapitulates renewal and repair, and the architecture and functionality of the adult tubular epithelia. In the future, the model will allow detailed investigations of trajectories of self-renewing cells towards both the partial recreation and malignant transformation of the kidney. Clear cell renal cell carcinoma (ccRCC) is the most common and aggressive kidney cancer. Inactivation of the Von Hippel-Lindau (VHL) tumor suppressor gene is the major driver of ccRCC. Earlier, we identified the upregulation of Wnt and Notch signaling in CXCR4+MET+CD44+ cancer stem cells (CSCs) from primary human ccRCCs. Blocking Wnt and Notch in patient-derived xenografts, organoids and non-adherent spheres using small-molecule inhibitors impaired self-renewal of CSCs and tumor growth. To mimic CSC-governed human ccRCC in genetic mouse models, I started from the generation of two double mouse mutants; β-catenin-GOF; Notch-GOF and Vhl-LOF; β-catenin-GOF. Surprizingly, I observed neither tumors or tumor precursor lesions nor higher cell proliferation rates in the mutant kidneys. Further analyses revealed that the mutant mice displayed features of chronic kidney disease (CKD). Thus, β-catenin-GOF; Notch-GOF and Vhl-LOF; β-catenin-GOF mouse mutants did not develop kidney tumors under the given experimental conditions

Mice with renal-specific alterations of stem cell-associated signaling develop symptoms of chronic kidney disease but surprisingly no tumors

Previously, we found that Wnt and Notch signaling govern stem cells of clear cell kidney cancer (ccRCC) in patients. To mimic stem cell responses in the normal kidney in vitro in a marker-unbiased fashion, we have established tubular organoids (tubuloids) from total single adult mouse kidney epithelial cells in Matrigel and serum-free conditions. Deep proteomic and phosphoproteomic analyses revealed that tubuloids resembled renewal of adult kidney tubular epithelia, since tubuloid cells displayed activity of Wnt and Notch signaling, long-term proliferation and expression of markers of proximal and distal nephron lineages. In our wish to model stem cell-derived human ccRCC, we have generated two types of genetic double kidney mutants in mice: Wnt-β-catenin-GOF together with Notch-GOF and Wnt-β-catenin-GOF together with a most common alteration in ccRCC, Vhl-LOF. An inducible Pax8-rtTA-LC1-Cre was used to drive recombination specifically in adult kidney epithelial cells. We confirmed mutagenesis of β-catenin, Notch and Vhl alleles on DNA, protein and mRNA target gene levels. Surprisingly, we observed symptoms of chronic kidney disease (CKD) in mutant mice, but no increased proliferation and tumorigenesis. Thus, the responses of kidney stem cells in the tubuloid and genetic systems produced different phenotypes, i.e. enhanced renewal versus CKD

The application of organ-on-chip models for the prediction of human pharmacokinetic profiles during drug development

Organ-on-chip (OoC) technology has led to in vitro models with many new possibilities compared to conventional in vitro and in vivo models. In this review, the potential of OoC models to improve the prediction of human oral bioavailability and intrinsic clearance is discussed, with a focus on the functionality of the models and the application in current drug development practice. Multi-OoC models demonstrating the application for pharmacokinetic (PK) studies are summarized and existing challenges are identified. Physiological parameters for a minimal viable platform of a multi-OoC model to study PK are provided, together with PK specific read-outs and recommendations for relevant reference compounds to validate the model. Finally, the translation to in vivo PK profiles is discussed, which will be required to routinely apply OoC models during drug development

The Role of Hypoxia and Cancer Stem Cells in Renal Cell Carcinoma Pathogenesis

International audienceThe cancer stem cell (CSC) model has recently been approached also in renal cell carcinoma (RCC). A few populations of putative renal tumor-initiating cells (TICs) were identified, but they are indifferently understood ; however, the first and most thoroughly investigated are CD105-positive CSCs. The article presents a detailed comparison of all renal CSC-like populations identified by now as well as their presumable origin. Hypoxic activation of hypoxia-inducible factors (HIFs) contributes to tumor aggressiveness by multiple molecular pathways, including the governance of immature stem cell-like phenotype and related epithelial-to-mesenchymal transition (EMT)/de-differentiation, and, as a result, poor prognosis. Due to intrinsic von Hippel-Lindau protein (pVHL) loss of function, clear-cell RCC (ccRCC) develops unique pathological intra-cellular pseudo-hypoxic phenotype with a constant HIF activation, regardless of oxygen level. Despite satisfactory evidence concerning pseudo-hypoxia importance in RCC biology, its influence on putative renal CSC-like largely remains unknown. Thus, the article discusses a current knowledge of HIF-1 alpha/2 alpha signaling pathways in the promotion of undifferentiated tumor phenotype in general, including some experimental findings specific for pseudo-hypoxic ccRCC, mostly dependent from HIF-2 alpha oncogenic functions. Existing gaps in understanding both putative renal CSCs and their potential connection with hypoxia need to be filled in order to propose breakthrough strategies for RCC treatment

The application of organ-on-chip models for the prediction of human pharmacokinetic profiles during drug development

Organ-on-chip (OoC) technology has led to in vitro models with many new possibilities compared to conventional in vitro and in vivo models. In this review, the potential of OoC models to improve the prediction of human oral bioavailability and intrinsic clearance is discussed, with a focus on the functionality of the models and the application in current drug development practice. Multi-OoC models demonstrating the application for pharmacokinetic (PK) studies are summarized and existing challenges are identified. Physiological parameters for a minimal viable platform of a multi-OoC model to study PK are provided, together with PK specific read-outs and recommendations for relevant reference compounds to validate the model. Finally, the translation to in vivo PK profiles is discussed, which will be required to routinely apply OoC models during drug development