Figure 3.

GBM-and endothelial cell-derived APLN are both controlling sprouting angiogenesis. (A) U87MG was implanted into immunodeficient mice and grown to big xenografts within 28 dpi. Fluorescent immunostaining for CD31 was performed and is depicted in an overview and a close up view for every xenograft. (B) The microvasculature in the green fluorescent protein (GFP)-positive tumor area was analyzed by stereomorphology. In comparison to U87^NSCAPLN^WT controls (n = 8), VLD in U87^AKDAPLN^WT xenografts (n = 13) was reduced by 62% and vessel length by 75%. Additional loss-of-APLN expression in the tumor neo-vasculature of the APLN^KO mouse (U87^AKDAPLN^KO, n = 10) lead to further reduction of the tumor vasculature. VLD was also reduced when only the tumor cells express APLN (U87^NSCAPLN^KO, n = 9) but was the highest of all manipulated xenografts. While vascular complexity measured by vascular branch points (ABP values are 6, 2.3; 4.3; and 1.2, respectively) reflects the results seen by VLD, the total vessel length was highly reduced in all three xenografts with reduction of APLN expression. Data are reported as mean +/−SEM; statistical significance (one-way ANOVA plus Bonferroni´s post hoc test) is indicated ** p < 0.005, *** p < 0.0005.