Figure 6.

Morphometric analysis of the neointima at day 28. Composition of in-stent neointima at 28 days after stent implantation. (A) Masson’s trichrome staining. Black = nuclei, deep green = extracellular matrix, purple = cell cytoplasm, red = erythrocytes; light green/grey = ancient fibrin/platelets. Note the thick neointima and presence of leukocytes (black round nuclei) with the bare metal stent, the presence of fibrin, platelets, and erythrocytes with the drug-eluting stent and the organized media-like structure of the thin neointima with the CD31-mimetic stents. The black squares in low magnification images indicate the localization of the magnified insets. (B) Fluorescence microscopy analysis of Sirius Red-stained resin cross-sections of stented arteries. Red = collagen and elastin; green = stromal cell cytoplasm. White dotted line = internal elastic lamina. Note the consistent presence of stromal cells (green) in the media of arteries implanted with CD31-mimetic stents as compared to their paucity when implanted with drug-eluting stent and virtual absence with bare metal stent. Several stromal cells were also visible with bare metal stent but localized in the neointima (tissue growing inward of the stent struts and internal elastic lamina). (C) Quantitative analysis of neointima surface area (µm²). Individual points are median values from three sections (proximal, middle and distal cross-section) of each sample.