Figure 4: Effect of donor age and passage number on the angiogenic potential of ASC-CM in the HUVEC tube formation assay. Conditioned media were collected from cultured ASCs at passages 2, 4, and 6 from donors of different ages and used in the HUVEC tube formation assay. After 11 days of culture, HUVEC tube-like structures were visualized with CD31 immunostaining and photographed. Unconditioned medium was the negative control (NC), and medium containing 10 ng/ml VEGF-A was the positive control (PC). Total tube length and total tube area in three random fields were quantified. Data shown are the mean ± SD of results from triplicate dishes. *p < 0.05 vs NC, #p < 0.05 vs PC (One-way ANOVA and Tukey’s multiple comparison test).