Exosomes derived from human bone marrow mesenchymal stem cells promote tumor growth in vivo

Mesenchymal stem cells (MSCs) can promote tumor growth in a mouse xenograft model, but the exact mechanism remains unclear. In this study, we investigated the effects of bone marrow MSC-derived exosomes (MSC-exosomes) on tumor growth in vitro and in vivo. Our results showed that MSC-exosomes promoted tumor growth in vivo. MSC-exosomes enhanced vascular endothelial growth factor (VEGF) expression in tumor cells by activating extracellular signal-regulated kinase1/2 (ERK1/2) pathway. Inhibition of ERK1/2 activation reserved the increase of VEGF level by MSC-exosomes. Our findings demonstrate a new mechanism through which MSC-exosome-mediated cell-cell interactions may contribute to tumor progression. (C) 2011 Elsevier Ireland Ltd. All rights reserved.