Figure 4.

Apelin peptide rescues the vascular loss-of-function phenotype. (A) Intracerebral infusion of 30 µg of apelin-13 peptide (n = 9) increased glioma angiogenesis in U87^AKDAPLN^KO xenografts compared to infusion of artificial cerebrospinal fluid (aCSF, n = 8) or apelin-F13A (n = 6) antagonist as shown by von Willebrand factor (VWF) staining. (B) Quantification on a Stereoinvestigator resulted in a VLD of 1269 mm/mm³ in U87^AKDAPLN^KO xenografts infused with aCSF only; 2573 mm/mm³ with the APLN receptor (APLNR) agonist apelin-13 peptide or 1419 mm/mm³ with the APLNR antagonist apelin-F13A. ABP obtained were 2.2; 3.9 and 2.2, respectively. Data are reported as mean +/−SEM; statistical significance (one-way ANOVA plus Bonferroni´s post hoc test) is indicated. * p < 0.05, ** p < 0.005.