ABSTRACT
<p><b>OBJECTIVE</b>Bone-marrow derived mesenchymal stem cells (BMSC) have the potential to differentiate into endothelial cells. The aim of the study was to investigate the induction process of BMSC by B16 melanoma cells in vitro and to analyze the role of VEGF-a in the process.</p><p><b>METHODS</b>A co-culture system containing BMSC and B16 melanoma cells based on transwell indirect model was established, and the induction process of BMSC by B16 melanoma cells was studied in vitro.</p><p><b>RESULTS</b>BMSC were isolated from the bone marrow of C57 mice. BMSC expressed CD105, CD90, CD73, CD44 and CD166, and acquired expressin of endothelial phenotype markers including VEGFR-1, VEGFR-2 and Factor VIII after co-culture with B16 melanoma cells for 48 hours. The expression level of VEGFR-2 would be double and Factor VIII threefold more by extending the co-culture time to 72 hours. In the co-culture system, B16 melanoma cells also up-regulated the expression of VEGF-a.</p><p><b>CONCLUSIONS</b>VEGF-a plays a significant role in the differentiation of BMSC into cells of endothelial phenotype, therefore, is important to tumor angiogenesis.</p>