Glioma stem cells-derived exosomes promote the angiogenic ability of endothelial cells through miR-21/VEGF signal

// Xu Sun 1, * , Xiaotang Ma 2, * , Jinju Wang 3 , Yuhui Zhao 4 , Yue Wang 3 , Ji C. Bihl 3 , Yanfang Chen 2, 3 , Chuanlu Jiang 1 1 Department of Neurosurgery, The Second Affiliated Hospital, Harbin Medical University, Harbin 150086, China 2 Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Institute of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524000, China 3 Department of Pharmacology & Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA 4 Department of Neurology and Stroke Center, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510000, China * These authors equally contributed to this work Correspondence to: Xu Sun, email: suen0321@163.com Chuanlu Jiang, email: jcl6688@163.com Keywords: GSCs, exosomes, miR-21, VEGF, angiogenesis Received: January 16, 2017      Accepted: March 21, 2017      Published: March 29, 2017 ABSTRACT Glioma stem cells (GSCs) play an important role in glioblastoma prognosis. Exosomes (EXs) mediate cell communication by delivering microRNAs (miRs). Glioblastoma has a high level of miR-21 which could upregulate vascular endothelial growth factor (VEGF) expression. We hypothesized GSC-EXs can promote the angiogenic ability of endothelial cells (ECs) through miR-21/VEGF signal. GSCs were isolated from U-251 cells with stem cell marker CD133. GSCs transfected without or with scramble or miR-21 mimics were used to produce GSC- EXs con, GSC-EXs sc and GSC-EXs miR-21 . Human brain ECs were co-cultured with vehicle, GSC-EXs con , GSC-EXs sc or GSC-EXs miR-21 plus VEGF siRNAs (siRNA VEGF ). After 24 hours, the angiogenic abilities of ECs were evaluated. The levels of miR-21, VEGF and p-Flk1/VEGFR2 were determined. Results showed: 1) Over 90% of purified GSCs expressed CD133; 2) The levels of miR-21 and VEGF in GSCs and GSC-EXs were up-regulated by miR-21 mimic transfection; 3) Compared to GSC-EXs con or GSC-EXs sc , GSC-EXs miR-21 were more effective in elevating the levels of miR-21 and VEGF, and the ratio of p-Flk1/VEGFR2 in ECs; 4) GSC-EXsmiR-21 were more effective in promoting the angiogenic ability of ECs than GSC-EXs con or GSC-EXs sc , which were remarkably reduced by siRNA VEGF pretreatment. In conclusion, GSC-EXs can promote the angiogenic ability of ECs by stimulating miR-21/VEGF/VEGFR2 signal pathway.