In vivo angiogenic potential of MAPC and MSC seeded onto demineralized bone matrix (DBM) scaffolds. Representative photomicrographs of formation of new blood vessels in 2-week-old fractures treated with (a) scaffold only, (b) MAPC + DBM scaffold, or (c) MSC + DBM scaffold. Capillaries (arrows) within the developing fracture calluses illustrate more vascularization in fractures treated with MAPC or MSC in addition to the DBM scaffold (*). Hematoxylin and eosin stain, 40× magnification. (d)–(f) von Willebrand Factor (vWF) staining to illustrate vasculature, at 20× magnification. Scaffold-only, MAPC + DBM scaffold, or MSC + DBM scaffold group was implanted into a bone void, and the resultant blood vessel formation was examined after 14 days. Statistically significant blood vessels were noticeable in defects receiving (e) MAPC + DBM scaffold, compared to either (f) MSC + DBM scaffold or (d) scaffold only. (b and e) The blood vessels in the MAPC + DBM scaffold treatment group appeared larger in size and more fully formed or functional (circular). (g) Histological evaluation revealed a significant increase in blood vessel ingrowth in defects treated with MAPC + DBM scaffold compared to MSC + DBM scaffold and scaffold only. Blood vessels were quantified via H&E stained sections (n = 16 sections analyzed for each, *p < 0.05 when compared to scaffold-only control, #p < 0.05 when compared to MAPC + DBM scaffold).