S3-enriched kidney proximal nephrons from stem cells facilitate tubular injury modelling

Chronic kidney disease (CKD) is a major global health challenge affecting >840 million people, with rising prevalence driven by common conditions including diabetes, hypertension, obesity, and drug toxicity. The proximal tubule (PT) is central to kidney function yet is highly injury-prone, particularly within the S3 segment which plays key roles in drug clearance and CKD pathology. Despite decades of in vitro PT model development, achieving accurate functional and structural segmentation of the PT with distinct PT sub-cell types has remained challenging. Here, we report an enrichment of S3-like cells within PT-enhanced kidney organoids (PT-EKO) that confers segment-specific functionality and injury susceptibility. This advanced platform facilitated physiologically relevant modelling of hyperglycaemia-induced damage, including rapid detection of injury biomarker Kidney Injury Molecule-1 (KIM-1). Integrating with both static and organ-on-chip culture systems, the translational potential of S3-enriched PT-EKO was underscored by its amenability to scale-up via cryopreservation of day 13 progenitors with retained differentiation capacity. PT-EKO applications were further broadened as an expandable high-yield source of isolatable PT cells, retaining PT characteristics across multiple passages and cryopreservation. Together, these findings present a high-fidelity platform for modelling tubular injury and advancing translational applications including CKD drug development, cell-specific nephrotoxicity testing and cellular therapies. SIGNIFICANCE STATEMENTAdvancing stem cell-based proximal nephron models, here we identify proximal tubule-enhanced kidney organoids (PT-EKO) as an enriched source of the nephrons most injury-prone cell type; S3 proximal tubule cells. This advanced platform provides physiologically-relevant modelling of tubular injury and a scalable source of high-quality PT cells, paving the way for more accurate modelling, screening, and cellular therapy applications.