a Peritoneal macrophage isolated from 1-month, 8-month, and 18-month 57Bl6/J mice were treated with AIBP and apoA-I, and stained with oil red O. b Quantification on the number of lipid droplets per cell in macrophages. N = 25 (control) and 28 (AIBP/apoA-I) for 8-month mice, 43 (control) and 39 (AIBP/apoA-I) for 18-month mice. c Effect of AIBP on old macrophages’ ability to promote angiogenesis of HRMECs. Macrophages (MΦ) isolated from 1-month and 18-month mice were pretreated with different combination of AIBP and apoA-I and co-cultured with HRMECs. d Quantitative analysis of total segment length of tubes of HRMECs in c. N = 7 (without co-culture), 10 (1-month MΦ + control), 6 (1-month MΦ + AIBP/apoA-I), 14 (18-month MΦ + control), and 13 (18-month MΦ + AIBP/apoA-I) fields. Data represent mean ± SEM in b, d. Statistical analysis was performed by two-tailed Student’s t-test (b) or one-way ANOVA with Tukey post hoc analysis (d). Scale bar, 25 µm in a, 1000 µm in c.