Neovascularization is increased in the IT of mice after allo-HCT. Allo-HCT was performed as described in the “Methods” section. (A) Intestines of mice from the indicated groups were digested and analyzed on day 14 after allo-HCT for the frequency of ECs using flow cytometry. Allo-HCT increased the number of CD34⁺ and CD31⁺ ECs in the total IT, as shown for representative flow cytometry images (left) and when quantified for each individual animal (right). The experiment was performed 3 times with at least 3 mice in each group, and the pooled results of the 3 independent experiments are shown. (B) RNA was isolated from IT of the indicated groups and used for comparative microarray analysis. Vascular endothelial growth factor (VEGF) (P = .003) and fibroblast growth factor (FGF) (P = .005) levels were significantly increased in the GvHD group as compared with BM controls. The experiment was performed once with 3 animals in each group. (C) Left panel: in vivo PET imaging of mice from the indicated groups after allo-HCT and application of [⁶⁸Ga]NODAGA-c(RGDfK) is shown for 4 representative time points (days 0, 2, 7, and 21 after allo-HCT). Right panel: [⁶⁸Ga]NODAGA-c(RGDfK) uptake over time is quantified in the abdominal area of mice, demonstrating a higher uptake in transplanted as compared with untreated animals, shown for 1 representative of 3 independent experiments, each performed with at least 3 animals per group. c, coronal; s, sagittal.