Glucocorticoid and Mineralocorticoid Receptors Cooperatively Drive Vascular Development in Human Kidney Organoids

Background: Stem cell derived kidney organoids have enormous potential in disease modeling and therapeutic development. However, organoids have poor endothelial cell differentiation and lack intrinsic vasculature. Additionally, few protocols provide a suitable environment for simultaneous co-differentiation of vasculature and tubular structures. Cortisol has known functional roles in embryonic development and its cognate receptors (glucocorticoid receptor and mineralocorticoid receptor; GR and MR respectively) enhance the transcriptional output of pro-endothelial transcription factors. But its role in vascular development is unknown. Methods: We assessed endothelial cell (EC) differentiation via western blot and vessel formation by 3D confocal imaging and volumetric image analysis in IMARIS. We used bulk RNA sequencing and RT-qPCR to measure EC-related gene expression during treatment and ELISA to evaluate secreted factors. Results: We found that hydrocortisone (HC) supplementation significantly increased endothelial cell protein expression (up to 12-fold) and vascular volume (~1% in control to ~3% in HC-treated) in renal organoids. We also found that the vasculature forms a lumen and that these vessels can infiltrate primitive glomerular compartments. Finally, bulk gene expression profiles suggested that HC-induced EC differentiation and vessel formation in these organoids is mediated through upregulation of angiopoietin 1 and not by VEGF. Conclusion: Our data suggests that cells from posterior intermediate mesoderm can be driven toward EC cell fate. This cell fate decision is influenced by activation of both the GR and MR. Finally, that the GR/MR-induced vascularization may be driven by upregulation of angiopoietin 1 and not by VEGF. Together, these data indicate a critical role for cortisol in vascular development in the developing kidney. Funding: Private Foundation Support