Enhanced metanephric specification to functional proximal tubule enables toxicity screening and infectious disease modelling in kidney organoids

While pluripotent stem cell-derived kidney organoids represent a promising approach for the study of renal disease, renal physiology and drug screening, the proximal nephron remains immature with limited evidence for key functional solute channels. This may reflect early mispatterning of the nephrogenic mesenchyme or insufficient maturation. In this study, prolonged differentiation and modification of media conditions to enhance metanephric nephron progenitor specification resulted in the induction of nephrons containing elongated and aligned proximal nephron segments together with SLC12A1+ loops of Henle. Nephron proximal segments showed superior HNF4A gene and protein expression, as well as upregulation of key functional transporters, including SLC3A1/2, SLC47A1, and SLC22A2. The striking proximo-distal orientation of nephrons was shown to result from localised WNT antagonism originating from the centre of the organoid. Functionality of such transporters was evidenced by albumin and organic cation uptake, as well as appropriate KIM-1 upregulation in response to the nephrotoxicant, cisplatin. PT-enhanced organoids also possessed improved expression of receptors associated with SARS-CoV2 entry, rendering these organoids susceptible to infection and able to support viral replication without co-location of ACE2 and TMPRSS2. These PT-enhanced organoids provide an accurate model with which to study human proximal tubule maturation, inherited and acquired proximal tubular disease, and drug and viral responses.