Figure 2.

Endothelial APLN expression controls formation of a complex GBM vasculature. Orthotopic GL261 implants in APLN^WT or APLN^KO mice 21 days post-implantation (dpi). (A) The panels on the left indicate the tumor (tumor boarder highlighted by arrowheads) in the right brain hemisphere in overview and close up view on Hematoxylin & Eosin (H&E) sections. The in situ hybridization panels in the middle show the loss-of vascular APLN expression (arrows) in the tumor in overview and close up view when comparing APLN^WT to APLN^KO mice. The CD31-immunostaining shown in the panel on the right illustrates the reduced vessel density in APLN^KO mice. (B) Vessel length density (VLD) was assessed on CD31 immunofluorescent brain slides and demonstrated a significant decrease in APLN^KO mice. In addition, vascular complexity measured by the average branch points (ABP) was reduced in APLN^KO as compared to APLN^WT. (C) In the healthy brain, VLD and ABP do not differ in APLN^KO compared to APLN^WT mice. Data of n = 9 APLN^WT vs. 6 APLN^KO mice are reported as mean +/-SEM; statistical significance (students test) is indicated * p < 0.05.