Effects of ex vivo treatment with rapamycin-loaded NPs on vein graft neointima formation and reendothelializaton in rats at 21 days. A and B, Vein graft sections of animals treated with PLGA NPs (left, control) and with RPLGA-NPs (right, treated), stained with Hematoxylin and Eosin. D, Bar graphs represent the morphometric analysis of vein graft sections about the inhibition of hyperplasia (intima-media thickness) in different treatment groups. Quantitative data derived from 3 vein graft sections at different levels from each animal in each group. *P < 0.001 for treated (n = 5) versus control (n = 5) groups. C, Endothelial coverage within grafts was achieved using an immunohistochemistry stain for CD-31. E, Bar graphs represent no significant effect of control or RPLGA-NPs group P = 0.8. Bars represent mean ± 1SEM.