Project description: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.
Project description:Reduction in blood supply to the kidneys occurs to certain extent during acute kidney injury (AKI). Individuals who suffered AKI are at risk of developing chronic kidney disease (CKD) through a maladaptive repair process. Currently, the lack of a reliable research model that allows the characterization of the maladaptive regeneration during such transition, impedes the development of effective therapies. Here, we present the first human kidney organoid model that physiologically and morphologically resembles the AKI and the maladaptive regeneration. Kidney organoids were generated from human induced pluripotent stem cells. After 18 days of grow the organoids were under hypoxic conditions for 2 days to simulate AKI. Organoids were collected at day 20 to assess hypoxic injury, and after a 5-day recovery in normoxic conditions to assess maladaptive repair. The transcriptome, proteome and metabolome were profiled. Gene expression analysis of day 20 hypoxic organoids identified signatures of injury, cell death (necroptosis and ferroptosis), cell cycle arrest and changes in metabolism. The maladaptive repair phenotype was supported by enrichment of pathways associated with inflammatory signals, oxidative stress, and tissue remodelling. Specific genes associated with kidney injury and disease such as GDF15, MMP7, ICAM1, TGFB1, CCN1, C3 and S100A8/9 were upregulated. Single-cell RNA sequencing localized expression of maladaptive repair genes and activation of TNF and JAK-STAT signalling pathways specific to tubular epithelial cells. Dysregulation in metabolic pathways such as glycolysis and gluconeogenesis, amino acid and lipid metabolisms were conserved in this model. Altogether, these results support the use of kidney organoids as a model of AKI and early CKD that can be used for biomarker validation, elucidation of pathological mechanisms, and drug screening.
Project description:Chronic kidney disease (CKD) affects over half of all adults over 70 and 13% of the global population. The development of renal fibrosis is strongly correlated with loss of kidney function during CKD and involves cellular injury, excessive production of extracellular matrix proteins and inflammation. Current treatments focus on controlling blood pressure, controlling diabetes, and steroid therapies; however, we have no treatments to suppress renal fibrosis. Because hypoxia plays a key role in the development and progression of CKD, we have developed a new model of induced pluripotent stem cell-derived kidney organoids to study in vitro the development of fibrosis in a human model.
