Figure 2. Quantitation of microvessels in EC-seeded synthetic skin grafts. Tissue-engineered human skin substitutes seeded with Bcl-2-transduced HUVEC were found to have greater numbers of human CD31-positive vessels than nontransduced HUVEC controls. Treatment with rapamycin had no effect on the number of human CD31-positive vascular profiles in either case (A). By contrast, the number of human EC-lined vessels found in skin substitutes seeded with CB-EC or AB-EC was not affected by Bcl-2 transduction but, as with HUVEC, the number of human EC-lined vessels present was not affected by rapamycin administration (B, C). The number of human CD31-lined vessels was found to significantly greater in CB-EC than HUVEC or AB-EC, as groups (P<0.001). The number of murine CD31-positive vessels was also found to be greater in grafts seeded with Bcl-2-transduced HUVEC compared to nontransduced HUVEC controls (D). Seeding with either CB-EC or AB-EC the number of murine CD31-positive vessels and these responses were not affected by Bcl-2 transduction (E, F). In all cases, rapamycin treatment of the recipient significantly inhibited the formation of mouse EC-lined vessels within transplanted tissue engineered human skin substitutes. ANOVA analysis with Bonferroni posthoc test revealed a significantly greater number of human CD31-positive vessels in skin substitutes seeded with CB-EC than AB-EC or HUVEC, P < 0.001. (*P<0.05 vs. nontransduced controls. #P <0.01 vs. vehicle-treated control.)