Progressive renal damage and development of CKD in sickle mice. (A) Townes sickle (SS) mice from different age groups (1-10 months; n = 9; M, 5; F, 4) and older (10 months; n = 9; M, 3; F, 6) control (AA) mice were used to assess GFR noninvasively using a transcutaneous device. An age-dependent decline in GFR was evident with hyperfiltration in younger (1-month) SS mice. (B) Urinary albumin and creatinine were measured in the urine collected from the same cohort of mice as in (A) before GFR measurement, and the ratio (uACR) indicated a significant increase in albuminuria. (C) Plasma Cys C, measured using enzyme-linked immunosorbent assay in the same cohort of mice, was higher in SS mice of all ages than in AA mice. (D) Elevated urinary KIM-1 in the SS mice, with no difference between older AA and 1-month-old SS mice. (E) Representative hematoxylin and eosin images showing an age-dependent increase in renal microvascular congestion (arrows) in SS mice (scale bar = 20 μm). (F) SRU images of the kidneys in a separate cohort of AA (10-month; n = 3; M, 2; F, 1) and SS (1-month [n = 3; M, 2; F, 1] and 10-month [n = 3; M, 2; F, 1]) mice, showing representative overlaid B-mode images. Quantitation of vessel density in the (G) cortex and (H) corticomedullary regions of interest, as described in the supplemental Methods, showing a loss of renal microvasculature in older SS mice (n = 3). (I) Reduced renal blood volume (rBV) in older SS mice compared with age-matched AA mice (n = 3). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001 (1-way analysis of variance (ANOVA) between differentially aged SS mice and unpaired Student t test between 10-month-old AA and SS mice). F, female mice; M, male mice; ns, nonsignificant.