Hypoxic injury triggers maladaptive repair in human kidney organoids

Acute kidney injury (AKI) is a common clinical disorder linked to high rates of illness and death. Ischemia is a leading cause of AKI, which can result in chronic kidney disease (CKD) through a maladaptive repair process characterised by failed epithelial regeneration, inflammation, and metabolic dysregulation. No targeted therapies exist to prevent AKI from progressing to CKD, and insight into ischemic AKI and maladaptive repair in humans remains limited. In this study, we report that human kidney organoids recapitulate select molecular and metabolic signatures of AKI and maladaptive repair in response to hypoxic injury. Transcriptional, proteomic, and metabolomic profiling revealed signatures of tubular injury, cell death, cell cycle arrest and altered metabolism in kidney organoids cultured in hypoxic conditions. After a recovery period in normoxic conditions, hypoxic injured organoids had increased signatures associated with maladaptive repair like the TNF signalling pathways and S100A8/9. Single cell RNA sequencing localised AKI and maladaptive repair markers such as GDF15, MMP7, ICAM1, TGFB1, SPP1, C3 and CCN1 to injured proximal and distal tubules. Metabolic phenotypes linked to CKD were also evident including dysregulated glycolysis and gluconeogenesis, amino acid, bicarbonate and lipid metabolism, and elevated ceramide levels. In addition, by developing a kidney organoid-macrophage co-culture model, we showed a significant activation of macrophages in response to hypoxia, marked by a shift towards an inflammatory state. In summary, our multi-omic analysis provides compelling evidence for the use of kidney organoids as a model of human ischemic AKI and maladaptive repair, highlighting new and conserved biomarkers and mechanisms, and opportunities for drug screening.