Fig. 5: Granular cast accumulation precedes proliferation in non-necrotic tubule epithelium downstream of necrotic injury sites.
From: Longitudinal tracking of acute kidney injury reveals injury propagation along the nephron
a Representative serial in vivo 2-photon microscopy images of a Mid region in CycB1-GFP kidneys at day 0, 1, and 2 after partial IRI. Note how GFP+ cells (arrowheads) appear 1 day after granular cast accumulation (arrows) in initially non-necrotic segments (PI-negative at day 0). Scale bar: 100 μm. b Representative stereomicroscope photo of a mouse kidney during renal artery branch occlusion showing a typical border region between the perfused and ischemic kidney regions. c, d Luminal granular cast area measured at the largest cross-sectional plane of each tubular segment and normalized by the cross-sectional area of the respective segment at the same imaging depth, grouped by days after partial IRI (c) (n = 468, 328, 329, and 320 segments for respective days from 6 (day 00) and 4 (day 01-03) mice), and segment type in the absence or presence of necrosis (d), respectively (n = 213 and 221 for non-necrotic and necrotic PT-S1 from 4 mice; 269 and 274 segments for non-necrotic and necrotic PT-S2 from 4 and 3 mice, respectively). Any tubule with >1% PI+ necrotic cells at day 0 was classified as necrotic; mean ± 95% CI with scatterplots. Statistical test: linear mixed-effect model, p-values from two-sided test, no adjustment for multiple comparisons (Supplementary Extended Statistics.o). e Linear regression of luminal granular cast area (% of total segment cross-sectional area) and GFP+ nuclei (% of total nuclei/ segment, assessed in 3D) measured 24 h later in the same segment and proliferating outside a 25 µm radius from any PI+ nucleus (n = 179 and 184 for non-necrotic and necrotic segments from 4 and 3 mice, respectively). Fit (slope*x + intercept, plotted with 95% CI); R2 and Pearson’s correlation coefficient (r) are reported for both. #: significant difference of slope and intercept from zero. *: significant difference between the segment types, p-values from two-sided test, */#: p < 0.05; **/##: p < 0.01; ***/###: p < 0.001.
