Effect of HB-EGF on mesenchymal stem cell (MSC) engraftment into intestines subjected to experimental necrotizing enterocolitis. Shown are representative images from pups subjected to: (A) NEC+MSC IP; (B) NEC+HB-EGF+MSC IP; (C) NEC+MSC IV; or (D) NEC+HB-EGF+MSC IV. Cell nuclei are indicated by blue fluorescent (DAPI) staining and engrafted YFP-positive mesenchymal stem cells are indicated by green fluorescent staining (white arrows). Magnification x100. (E) Quantification of MSC engraftment. Values represent mean ± SD, n=12-16 animals in each group. Statistical symbols for 1-way ANOVA with Turkey test are: †p<0.01 vs *; § p<0.05 vs ‡; ‡p<0.05 vs *. HB-EGF, heparin binding EGF-like growth factor; NEC, necrotizing enterocolitis; YFP, yellow fluorescent protein; MSC, mesenchymal stem cells; IP, intraperitoneal; IV, intravenous.