Fig. 1: Expanding mouse UB progenitor cells into 3D branching UB organoids.

a Schematic of mouse UB isolation and screening for UB organoid culture condition. b Representative bright field (BF, left panel) and Wnt11-RFP (right panel) images of UB organoid. Scale bars, 200 µm. c Cumulative growth curve of UB organoid culture starting from 2000 cells. Each time point represents three biological replicates. d Whole-mount immunostaining of UB organoid for various UB markers at Day 10 of culture. The four panels on the right represent the boxed region in the left panel. Scale bars, 100 µm. e Quantification of percentages of UB cells stained positive for different UB markers in Fig. 1d and Supplementary Fig. 2a, b. Each column represents counts from three different fields of view (n = 3). f Principal component analysis (PCA) of RNA-seq data. Different colors and oval circles represent different primary kidney cell populations (NPC, IPC, UB tip, and UB trunk) or UB organoids cultured for 5 (D5), 10 (D10), and 20 days (D20). g Summary of UB organoid derivation from mouse strains with different genetic backgrounds or with different derivation methods. h Bright field (BF) images showing single UB cells, derived from Wnt11-RFP mice, cultured in the UBCM on Days 1 (left panel) and 5 (middle panel), as well as Wnt11-RFP image on Day 5 (right panel). Scale bars, 200 µm. i UB organoid derivation from a single UB cell-derived budding structure isolated from the boxed region in (h) at Days 0 (D0, the day of isolation and re-embedding into Matrigel), 2 (D2), 4 (D4), and 6 (D6). All images in (i) have been scaled to share the same scale bar with the D6 image. Scale bar, 400 µm. All data are presented as mean ± s.d. Source data are provided as a Source Data file.