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Updated: Jul 8, 2025
Optimization of Renal Organoid and Organotypic Culture for Vascularization, Extended Development, and Improved Microscopy Imaging
Published on: March 28, 2020
RAAS-deficient organoids indicate delayed angiogenesis as a possible cause for autosomal recessive renal tubular
Naomi Pode-Shakked1,2,3,4, Megan Slack1,2, Nambirajan Sundaram5
1Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
Abstract:
Autosomal Recessive Renal Tubular Dysgenesis (AR-RTD) is a fatal genetic disorder characterized by complete absence or severe depletion of proximal tubules (PT) in patients harboring pathogenic variants in genes involved in the Renin-Angiotensin-Aldosterone System. To uncover the pathomechanism of AR-RTD, differentiation of ACE-/- and AGTR1-/- induced pluripotent stem cells (iPSCs) and AR-RTD patient-derived iPSCs into kidney organoids is leveraged. Comprehensive marker analyses show that both mutant and control organoids generate indistinguishable PT in vitro under normoxic (21% O2) or hypoxic (2% O2) conditions. Fully differentiated (d24) AGTR1-/- and control organoids transplanted under the kidney capsule of immunodeficient mice engraft and mature well, as do renal vesicle stage (d14) control organoids. By contrast, d14 AGTR1-/- organoids fail to engraft due to insufficient pro-angiogenic VEGF-A expression. Notably, growth under hypoxic conditions induces VEGF-A expression and rescues engraftment of AGTR1-/- organoids at d14, as does ectopic expression of VEGF-A. We propose that PT dysgenesis in AR-RTD is primarily a non-autonomous consequence of delayed angiogenesis, starving PT at a critical time in their development.
Insights
Autosomal Recessive Renal Tubular Dysgenesis (AR-RTD) stems from Renin-Angiotensin-Aldosterone System gene defects. Delayed angiogenesis, not intrinsic kidney defects, likely causes AR-RTD by impairing proximal tubule development.
Area of Science:
- Nephrology
- Developmental Biology
- Genetics
Background:
- Autosomal Recessive Renal Tubular Dysgenesis (AR-RTD) is a fatal condition characterized by absent or depleted proximal tubules (PT).
- Pathogenic variants in Renin-Angiotensin-Aldosterone System (RAAS) genes are implicated in AR-RTD.
- Understanding AR-RTD pathomechanism requires investigating kidney development and RAAS signaling.
Purpose of the Study:
- To investigate the pathomechanism of Autosomal Recessive Renal Tubular Dysgenesis (AR-RTD).
- To determine the role of RAAS signaling in kidney organoid development and function.
- To explore the impact of angiogenesis on PT development in AR-RTD models.
Main Methods:
- Differentiation of induced pluripotent stem cells (iPSCs) from ACE-/-, AGTR1-/-, and AR-RTD patients into kidney organoids.
- In vitro analysis of proximal tubule (PT) differentiation under normoxic and hypoxic conditions.
- In vivo transplantation of kidney organoids into immunodeficient mice to assess engraftment and maturation.
Main Results:
- Mutant and control kidney organoids showed indistinguishable PT development in vitro.
- AGTR1-/- organoids exhibited impaired engraftment at d14 due to reduced VEGF-A expression.
- Hypoxia or ectopic VEGF-A expression rescued the engraftment defect in AGTR1-/- organoids.
Conclusions:
- AR-RTD pathogenesis may result from delayed angiogenesis impairing PT development.
- VEGF-A mediated angiogenesis is crucial for proper kidney organoid engraftment and maturation.
- This study highlights a non-autonomous mechanism in AR-RTD, linking RAAS signaling to vascular development.
