Fig. 3 |. DDR2⁺ CSCs are endochondral-specialized.

a, b, Bone organoids after renal capsule transplantation, 4 weeks. c, Cryo-sectioned bone organoids derived from DDR2⁺ CSCs (red) from Ctsk-Cre;mTmG mice. No interconversion of DDR2⁺ CSCs (red) into CTSK⁺ CSCs (green) is seen. Inset, additional DDR2 immunostaining. d, Timecourse of the bone organoids. von Kossa staining (black) for mineralized bone and Safranin O (red) for cartilage in adjacent serial sections. e, Timecourse immunofluorescence for markers of endochondral ossification in DDR2⁺ CSC-derived bone organoids 2, 4, and 8 weeks post-transplantation. f, H&E and immunostaining for markers of hematopoietic cells in organoids from femur SSCs, DDR2⁺ CSCs, or CTSK⁺ CSCs. g, FACS plots indicating recruitment of hematopoietic populations to femoral SSC-derived (n=4) or DDR2⁺ CSC-derived (n=3) bone organoids. Lin, CD3, Gr-1, CD11b, B220, and Ter119. Total Lin⁻cKit⁺ cells (LK); Total Lin⁻Sca1⁺cKit⁺ cells (LSK); Long-term hematopoietic stem cells (LT-HSC, Lin⁻Sca1⁺cKit⁺CD150⁺CD48⁻); Short-term HSC (ST-HSC, Lin⁻Sca1⁺cKit⁺CD150⁻CD48⁻); Multipotent progenitors (MPP, Lin⁻Sca1⁺cKit⁺CD150⁻CD48⁺). h, Principal component analysis (PCA) of the CTSK⁺ CSC and DDR2⁺ CSC transcriptome profiling after isolation from P7 suture (n=5). i, Heatmap of gene expression. The color scale bar shows Z-score values on normalized read counts across the samples. ****P < 0.0001, P values are shown. Mean ± s.d., unpaired two-tailed Student’s t-test. Images in b-f are representative of a minimum of three (d, e) and five (b, c, and f) independent experiments. Scale bars, 1.0 mm, b; 100 μm, c, e, f; 200 μm, d.