Dissection and Culture of Mouse Embryonic Kidney

Deciphering the cellular and molecular landscapes of Wnt/β-catenin signaling in mouse embryonic kidney development

Background

The Wnt/β-catenin signaling pathway is critical in kidney development, yet its specific effects on gene expression in different embryonic kidney cell types are not fully understood.

Methods

Wnt/β-catenin signaling was activated in mouse E12.5 kidneys in vitro using CHIR99021, with RNA sequencing performed afterward, and the results were compared to DMSO controls (dataset GSE131240). Differential gene expression in ureteric buds and cap mesenchyme following pathway activation (datasets GSE20325 and GSE39583) was analyzed. Single-cell RNA-seq data from the Mouse Cell Atlas was used to link differentially expressed genes (DEGs) with kidney cell types. β-catenin ChIP-seq data (GSE39837) identified direct transcriptional targets.

Results

Activation of Wnt/β-catenin signaling led to 917 significant DEGs, including the upregulation of Notum and Apcdd1 and the downregulation of Crym and Six2. These DEGs were involved in kidney development and immune response. Single-cell analysis identified 787 DEGs across nineteen cell subtypes, with Macrophage_Apoe high cells showing the most pronounced enrichment of Wnt/β-catenin-activated genes. Gene expression profiles in ureteric buds and cap mesenchyme differed significantly upon β-catenin manipulation, with cap mesenchyme showing a unique set of DEGs. Analysis of β-catenin ChIP-seq data revealed 221 potential direct targets, including Dpp6 and Fgf12.

Conclusion

This study maps the complex gene expression driven by Wnt/β-catenin signaling in embryonic kidney cell types. The identified DEGs and β-catenin targets elucidate the molecular details of kidney development and the pathway's role in immune processes, providing a foundation for further research into Wnt/β-catenin signaling in kidney development and disease.

Exploring porcine kidney explants as a model for the study of nephrotoxins and the therapeutic potential of phytic acid

The use of in vivo models to assess nephrotoxicity has faced ethical limitations. A viable alternative is the ex vivo model that combines the 3 R principles with the preservation of tissue histology. Here, we established a gentamicin nephrotoxicity model using pigs` kidney explants and investigated the effect of phytic acid (IP6) against gentamicin- induced nephrotoxicity. A total of 360 kidney explants were divided into control, gentamicin (10 mM), IP6 (5 mM), and gentamicin+IP6 groups. The activity of gammaglutamyltransferase (GGT), creatinine levels, histological assessment, oxidative stress, and inflammatory cytokine expression were analyzed. Exposure to gentamicin induced an increase in GGT activity, creatinine levels, lesion score, lipoperoxidation and IL-8 expression. Explants exposed to IP6 remained like the control. The addition of IP6 to gentamicin prevented tissue damage, increasing the antioxidant status and gene expression of IL-10. This model proved to be an adequate experimental approach for identifying nephrotoxins and potential products to modulate the toxicity.

Adult kidney explants is a physiologic model for studying diabetic nephropathy

Inflammatory processes play a central role in the pathogenesis of diabetic nephropathy (DN) in the early stages of the disease. In vitro approach using cell lines help to understand the mechanisms involves and allow the molecular and biochemical processes. Adult kidney (AK) explants remain an essential instrument for advancing our understanding of the molecular and cellular regulation of signalling pathways from an organotipic view with physiological system interaction integrated. AK explants from T1DM animal model (BB rat) are obtained by slicing central kidney area preserving the organ's cytoarchitecture and reproduce the classical events detected during the DN in an in vivo model such as inflammation, epithelial-mesenchymal transition (EMT) processes by the modulation of a-SMA and e-Cadherin among others which have been determined by qRT-PCR, western-blot and immunohistochemistry. In this regard, AK explants reproduce the signalling pathways involve in DN progression (proinflammatory NFkB and inflammasome complex). This work demonstrates AK explants is a physiological experimental approach for studying the development and progression of DN. Furthermore, the inflammatory processes in AK explants under a diabetic environment and/or BB rats could be modulated by potential treatments for DN.

Mouse Ex Vivo Kidney Culture Methods

Kidney organogenesis has been a widely used classical model system to study inductive tissue interactions that guide differentiation of many organs. The basis for this is in the pioneering work done during the early 1950s when the conditions of how to support ex vivo growth and differentiation of developing kidneys were revealed. Importantly, culturing developing kidneys remains as an essential instrument to advance our understanding of molecular and cellular regulation of morphogenesis even today. Despite the fact that embryonic kidneys have been cultured for decades, it is not a trivial method and requires specific anatomical and developmental biology knowledge. This chapter outlines the general steps in organ culture and details the requirements for successful kidney explant differentiation.