Preservation of renal health after heme-induced CKD in SCD mice with EPCR overexpression. (A-D) EPCR-WT and EPCR-Ox mice underwent transplantation with SS bone marrow to create sickle chimera mice with normal (SS^EPCR-WT) and overexpression (SS^EPCR-Ox) of EPCR on the vascular endothelium. The mice were then subjected to a multiheme challenge. GFR was measured, and plasma and urine samples were collected at baseline (BL) and 7 days after the last heme injection (H). Worsening renal function showing (A) reduced GFR and increased (B) uACR, (C) plasma Cys C, and (D) urinary KIM-1 in SS^EPCR-WT compared with SS^EPCR-Ox mice (n = 5-7; M, 2-3; F, 3-4). (E) Plasma sEPCR at BL and after the multiheme challenge in SS^EPCR-WT and SS^EPCR-Ox mice (n = 6; M, 3; F, 3). (F) Total thrombin in the kidney tissues harvested from SS^EPCR-WT and SS^EPCR-Ox mice (n = 5-6; M, 2-3; F, 3). (G) Representative restructured SRU images showing the scarcity of renal vasculature in SS^EPCR-WT mice (n = 3; M, 1; F, 2). (H-I) Quantitation of vessel density in SS^EPCR-WT and SS^EPCR-Ox mice (n = 3). (J-K) Calculated renal blood flow in the indicated sickle bone marrow chimera mice after multiheme challenge (n = 3). (L) Representative stitched images (scale bar = 500 μm) of the whole kidney from the multiheme-challenged SS^EPCR-WT and SS^EPCR-Ox mice. The indicated areas are digitally enlarged to show corticomedullary congestion (arrowhead). Serial tissue sections stained for smooth muscle actin showing microvessel distribution in the indicated area (scale bar = 100 μm). (M-N) Representative immunofluorescence images (scale bar = 50 μm) and quantitation of the EPCR/CD31 intensity ratio in renal tissue sections from SS^EPCR-WT and SS^EPCR-Ox mice (n = 3) after heme challenge. ∗P < .05; ∗∗P < .001 (paired and unpaired Student t test).