fig1

Figure 1. A schematic visualizing the reprogramming of endothelial cells by exosomes. A: exosomes carry a variety of pro-angiogenic factors including the ectonucleotidases CD39 and CD73. Besides surface-bound molecules, exosomes encapsulate pro-angiogenic factors, nucleic acids, adenosine, and cAMP, as well as other purine metabolites; B: tumor-derived exosomes interact directly with endothelial cells or reprogram other cells in the tumor microenvironment to release pro-angiogenic factors. All these interactions involve signaling via adenosine receptors expressed on responder cells: specifically, A_2BR on endothelial cells, A₁R on monocytes, A_2AR and A_2BR on macrophages, and A_2BR and A₃R on mast cells. miRNA: microRNA; VEGF: vascular endothelial growth factor; FGF: fibroblast growth factor; TGF-β: transforming growth factor beta; MMPs: matrix metalloproteinases; ICAM-1: intercellular adhesion molecule 1; uPA: urokinase-type plasminogen activator; IL-8: interleukin 8; cAMP: cyclic adenosine monophosphate