Activated platelet supernatant can augment the angiogenic potential of human peripheral blood stem cells mobilized from bone marrow by G-CSF

Platelets not only play a role in hemostasis, but they also promote angiogenesis and tissue recovery by releasing various cytokines and making an angiogenic milieu. Here, we examined autologous 'activated platelet supernatant (APS)' as a priming agent for stem cells; thereby enhance their pro-angiogenic potential and efficacy of stem cell-based therapy for ischemic diseases. The mobilized peripheral blood stem cells ((PBSCs)-P-mob) were isolated from healthy volunteers after subcutaneous injection of granulocyte-colony stimulating factor. APS was collected separately from the platelet rich plasma after activation by thrombin. (PBSCs)-P-mob were primed for 6 h before analysis. Compared to naive platelet supernatants, APS had a higher level of various cytokines, such as 18, IL17, PDGF and VEGF. APS-priming for 6 h induced (PBSCs)-P-mob to express key angiogenic factors, surface markers (i.e. CD34, CD31, and CXCR4) and integrins (integrins alpha 5, beta 1 and beta 2). Also (PBSCs)-P-mob were polarized toward CD14(++)/CD16(+) pro-angiogenic monocytes. The priming effect was reproduced by an in vitro reconstruction of APS. Through this phenotype, APS-priming increased cell-cell adhesion and cell-extracellular matrix adhesion. The culture supernatant of APS-primed (PBSCs)-P-mob contained high levels of 18, IL10, 117 and TNF alpha, and augmented proliferation and capillary network formation of human umbilical vein endothelial cells. In vivo transplantation of APS-primed (PBSCs)-P-mob into athymic mice ischemic hindlimbs and Matrigel plugs elicited vessel differentiation and tissue repair. In safety analysis, platelet activity increased after mixing with (PBSCs)-P-mob regardless of priming, which was normalized by aspirin treatment Collectively, our data identify that APS-priming can enhance the angiogenic potential of (PBSCs)-P-mob, which can be used as an adjunctive strategy to improve the efficacy of cell therapy for ischemic diseases. (C) 2014 Elsevier Ltd. All rights reserved.