Matrix considerations. (A) RGD dose-dependent vacuolation of ECFC demonstrated by vacuole formation kinetics and represented images of vacuole vital stain FM 4-64 (cyan) at 24 hours. Scale bar is 100 μm. (Inset) High magnifications of single cells with abundant vacuoles in 3.7mM RGD. Scale bar is 20 μm. (B) Requisite of both RGD adhesion sites and MMP-degradable crosslinker for vacuolation of ECFC demonstrated by vacuole formation kinetics and represented images of vacuole vital stain FM 4-64 (cyan) at 24 hours. Significance levels were set at: #P > .05, *P < .05, and **P < .01. Scale bar is 50 μm.