Figure 3

Kidney-derived c-kit⁺ progenitor/stem cells present multi-compartment engraftment and differentiate into podocyte-like cells after PAN injection. (A–C) GFP-labelled c-kit⁺ cells were observed in the interstitial compartment of cortex, including the peri-glomerular region (*), and in tubular compartment of cortex and corticomedullar regions. (D) GFP-labelled c-kit⁺ cells stained for aquaporin-1 (AQP-1) in the Bowman’s capsule. Inset shows region at higher magnification (D’). GFP-labelled c-kit⁺ cells also stained for AQP-1 in proximal tubules (D”). Orthogonal slides of three-dimensional reconstructed images at all three different planes allows visualization of coexpression of fluorescence signals AQP-1 (red), GFP (green), ensuring that the yellow signal is not due to cell stacking (D”’). (E) GFP-labelled c-kit⁺ cells stained for smooth muscle actin (SMA) in a vessel, as demonstrated by 2-D confocal image (E’) (arrows). (F) GFP-labeled c-kit⁺ cells stained for α-Actinin-4 in glomeruli. Inset shows region at higher magnification (F’) (arrow). (G) GFP-labeled c-kit⁺ cells stained for synaptopodin in glomeruli. Inset shows higher magnification (G”) (arrows). (H) GFP-labeled c-kit⁺ cells stained for WT-1 in a few podocytes. 3-D confocal image shows the co-localization (H’) (arrows). (I,J) Clusters of GFP-labeled c-kit⁺ cells were also found in glomeruli and did not stain for VEGF and desmin. (K) GFP-MSCs did not engraft at day 21 after PAN injection. (L) GFP-antibody in saline group. (M) On day 21, the number of GFP-labeled c-kit⁺ cells was 4.6 ± 0.91 and 3.4 ± 1.15% in the glomerular and T-I compartments, respectively. No engraftment was observed in the MSC treated group. Scale bars represent 20 μm for confocal images. At day 10, n = 5 and n = 8 for saline and c-kit-treated group, respectively, and n = 12, n = 10, and n = 6 for saline, c-kit, and MSC-treated groups at day 21, respectively.