Quantification of functional engineered blood vessel density. Quantification of functional vessel density in SCID mice implanted with HUVECs alone or HUVECs with hMSCs (A) and HUVECs with hMSCs or 10T1/2 (B) (results are mean ± SEM, n = 3 in panel A and n = 5 in panel B; different batches of HUVECs were used in panels A and B, resulting in variation in vessel density between the 2 experiments). (C) The hMSC-stabilized vascular network remained functional for more than 130 days in vivo. Scale bar represents 100 μm.