Fig. 4.

Proliferation rates of human umbilical vein endothelial cells were measured by bromodeoxyuridine incorporation after 24 hours of incubation in conditioned media harvested from adipose-derived stromal cells that were exposed to normoxia (21% oxygen, red bars) or hypoxia (1% oxygen, blue bars) for 72 hours. Normoxic conditioned media harvested from young adipose-derived stromal cells had a significantly greater ability to increase proliferation of human umbilical vein endothelial cells than conditioned media harvested from aged, streptozotocin-induced, or db/db adipose-derived stromal cells (**p < 0.05). Conditioned media from hypoxic cultures also generated a significant increase in human umbilical vein endothelial cell proliferation that was even more pronounced than normoxia-exposed conditioned media (***p < 0.05) (n = 3 and N = 3).