Analysis of the tumor environment by confocal microscopy revealed a statistically significant increase in CD31 (platelet endothelial cell adhesion molecule-1, PECAM-1) expression in the xenografts treated with cEV (mean: 9.1 ± 3.5) compared to the NaCl control group (mean: 5.1 ± 1.1) (p = 0.0378) (Figure 3). Here, PECAM1 is linked to neoplasm.