FIG. 5.

(a) CD31 (brown) expression in modular constructs. Nuclei appear blue. The boxes in the low-magnification images (upper rows) show the location of the high-magnification images (lower rows). Static EC-only modules showed membrane-stained CD31⁺ cells around their perimeters, whereas flow cases showed some at day 7 but fewer at days 14 and 21. For MSC+EC modules under static and flow conditions, cells with CD31 membrane staining were apparent around the perimeter of the modules and within the intermodular regions, although their distribution appeared sparse. No membrane-stained CD31⁺ cells were observed in MSC-only cases (data not shown). Scale bars=25 μm. (b) The effect of flow and MSC on EC. The number of membrane-stained CD31⁺ cells (bars) and the total number of cells (inset table) found within an average 10×microscope field of the histological sections of the modular constructs. Unlike static EC-only modules, flow-conditioned EC-only modules had significantly fewer CD31⁺cells over time, indicating that the loss of EC was linked to flow. When MSC were added to the system, the sharp decline in the number of CD31⁺ cells in flow cases was not observed, suggesting that the MSC mitigated the complete loss of EC. That day 21 MSC+EC flow cases had more total cells than day 21 EC-only flow cases reflects the loss of EC in EC-only cases and the presence of the MSC in MSC+EC cases. Connecting lines represent a statistically significant difference between conditions (p<0.05, ANOVA), all error bars are±SEM, and the number of analyzed remodelign chambers (n) is shown in the inset table. F, flow; S, static. Color images available online at www.liebertonline.com/tea