Kidney organoid cell culture

The differentiation of hiPSCs (human‐induced pluripotent stem cells) (Jeon et al, 2018) into human kidney organoids was performed using STEMdiff™ Kidney Organoid Kit (StemCell Technologies, Vancouver, BC, Canada; 05160) following the manufacturer’s instructions. Briefly, hiPSCs (5.0 × 10³ cells/wells) were seeded in a black 96‐well Corning^® Matrigel^®‐coated plate (Corning, Corning, NY, USA; 356231) in mTeSR™1 medium (StemCell Technologies, Vancouver, BC, Canada; 85850) supplemented with 5× mTeSR™1 supplement (StemCell Technologies, Vancouver, BC, Canada; 85850) and 10 µM of Y‐27632 (StemCell Technologies, Vancouver, BC, Canada; 72302) and incubated in a 5% CO₂ incubator at 37°C. After 24 h, all media of the wells were replaced with 0.25 mg/ml of Matrigel^® and mTeSR™1 medium supplemented with 5× mTeSR™1 supplement without Y‐27632 to generate cavitated hPSCs spheroids. After 24 h, all media of the wells were replaced with 200 µl of STEMdiff™ kidney basal medium supplemented with 100× STEMdiff™ kidney supplement SG which was included in the kit to induce late primitive streak. After 36 h, all media were changed to STEMdiff™ kidney supplemented with STEMdiff™ kidney supplement DM (Stage 2 medium) in the kit. All media were changed with Stage 2 medium every 2–3 days during an 18‐day incubation period. Experiments were performed on the 18th day.