Array-based functional screening for genes that regulate vascular endothelial differentiation of Flk1-positive progenitors derived from embryonic stem cells.

Functional genomics is a central topic of current biological research, where a reverse genetic approach is one of the most promising strategies to discover functions of novel genes. Such an approach requires high-throughput methodologies to assess biological functions for a huge number of genes. We have developed a transfection array that permits parallel introduction of multiple plasmids separately into living cells. The feasibility of this array was examined in an assay system. Eleven genes were over-expressed alone, or in combination in vascular progenitors derived from embryonic stem cells. Endothelial differentiation of the cells was monitored through a stably transformed EGFP reporter construct that is expressed only in endothelial cells. Transcriptional activators that promote endothelial differentiation, such as Ets1 and Sox7, were identified. In addition, the assays also revealed an inhibitory effect on endothelial differentiation by several of the factors. These results demonstrate the feasibility of the transfection array for use in cell-based, high-throughput functional assays.