No early incorporation of EPCs in experimental models of GVHD and IBD. (A) Number of proliferating (Ki67⁺) ECs in colon of SYN and ALLO mice at day+2 after BMT (n = 3 per group). White arrow marks proliferating EC (4′,6-diamidino-2-phenylindole [DAPI⁺] [blue], Ki67⁺ [red-A555] in direct contact with CD31 [green-A488] signal). White asterisks mark proliferating crypt cells. (B) Representative pictures of green-A488 CD31 (vessel-related), DsRed (BM-related), and merged signals of colon and skin sections from SYN and ALLO mice at day+2 after BMT (DsRed+C57BL/6→B6D2F1). (C) Representative pictures of green-A488 CD31, DsRed, and merged signals of colon sections from DsRed⁺ BM chimeras at day+4 after DSS colitis induction. (D) Representative projections of Z-stacks of colon samples at day+4 after DSS induction from colitis-bearing and control mice, which received DsRed⁺ EPCs. Green A488-CD31 signal is vessel-related. Scale bar, 30 µm (A-C). Error bar indicates mean ± SEM. *P < .05 by Student t test (2-tailed).