MSC-induced apoptosis of EC-derived capillaries in matrigel. (A) Images are phase contrast (Ph) and TUNEL fluorescence in 4-day-old capillary cultures to which no cells were added (CT), or MSCs were added after 1 day of culture at 1:1 ratio to EC (MSC). Bar = 500 μm. Bar diagram shows corresponding group data. FB, at EC:RNLFB ratio of 1:1. Data are mean plus or minus SD; n = 3 for each group. *P < .05, significantly different from CT. (B) Immunoblot for cleaved caspase-3 in 4-day-old capillaries exposed to no cells (CT), MSC, or FB as above. Actin expression is shown in the bottom panel. Replicated 3 times.