Renal Redefined: The iPSC-Derived Proximal Tubular Model Moving Towards Chronic Toxicity Prediction

The development of induced pluripotent stem cell (iPSC)-derived renal models represents a significant advancement in nephrotoxicity testing, providing human-relevant systems capable of addressing the limitations of traditional methodologies. This thesis focuses on the derivation, characterization, and application of proximal tubular-like cells (PTLs) derived from iPSCs, establishing their utility as robust platforms for mechanistic investigations and chronic toxicity assessments. A streamlined and stepwise differentiation protocol was optimized to consistently generate PTLs that exhibit hallmark features of native renal proximal tubules, including megalin (LRP2) expression, albumin uptake, and active transport mechanisms. Functional and transcriptomic analyses confirmed the stability and physiological relevance of these cells. Mechanistic studies utilizing the PTL model identified a novel interferon-mediated immune response in aminoglycoside-induced nephrotoxicity, providing new insights into drug-induced renal injury. Similarly, cadmium toxicity studies highlighted oxidative stress and mitochondrial dysfunction as central pathways in heavy metal-induced kidney damage, further supporting the model’s applicability. Recognizing the variability inherent in differentiation methods, this thesis delves into how protocol differences affect transcriptomic outcomes, emphasizing the need for standardized approaches to ensure reproducibility and functional robustness. Moving beyond individual case studies, a novel framework integrating Key Characteristics (KCs) and the Adverse Outcome Pathway (AOP) concept is introduced, linking molecular events to chronic toxicity assessments and providing a bridge between mechanistic research and regulatory application. By aligning mechanistic insights with regulatory frameworks, this work positions iPSC-derived PTLs as scalable, reproducible, and human-specific alternatives to animal models. These advancements improve predictive capabilities for both acute and chronic nephrotoxicity, enabling safer drug development, more ethical testing practices, and a deeper understanding of long-term renal injury, while also contributing to personalized medicine.