Utility of co-transplanting mesenchymal stem cells in islet transplantation

Figure 2 Pro-angiogenic effect of mesenchymal stem cells. The process of revascularization requires proteolytic digestion of the vascular wall and subsequent migration, proliferation, and differentiation of endothelial cells (ECs). Mesenchymal stem cells (MSCs) express platelet-derived growth factor (PDGF) receptors and respond to PDGF production by ECs during revascularization. MSC-derived proteases promote EC migration and immature EC sprouts and upregulate the expression of angiopoietin and vascular endothelial growth factor (VEGF) in ECs, thereby promoting both angiogenesis and vascular stability. MSCs also produce VEGF and induce neovascularization. MSCs promote both donor and recipient EC proliferation, EC sprout formation, the ingrowth of ECs into islets and the formation of a vascular network between intra- and extra-islet vessels.