MicroRNA expression in CD34+-EC aggregates

To understand the the effect of microparticles conjugated with vascular endothelial growth factor (VEGF) on human endothelial cells derived from human umbilical cord blood (UCB) CD34+ hematopoietic stem cells, we have employed microRNA microarray profiling. The microparticles used in this study were purchased from Invitrogen (Dynal magnetic microparticles coated with streptavidin, 4.5 micron in size) and modified in our lab. Cell suspensions were mixed with blank microparticles (without VEGF), soluble VEGF or VEGF-conjugated microparticles and seeded as hanging drops to prepare endothelial cell aggregates. Cell aggregates without any treatments were used as control. After 2 h or 8 h, the cell aggregates were collected and miRNA expression profiles were detected. The microRNA expression in CD34+-EC aggregates was evaluated after incubation with blank microparticles, VEGF-conjugated microparticles, soluble VEGF or without treatment for 2 h (for all experimental groups) and 8 h (for soluble VEGF and VEGF-conjugated microparticle groups). Three independent experiments were performed at each time.