Enhanced Collagen Type IV Based Differentiation of Embryonic Stem Cells Towards Flk-1 Expressing Vascular Progenitors by the Wnt/β-Catenin Synergist QS11

Mouse embryonic stem (mES) cells when plated onto collagen type IV in the presence of serum-containing medium differentiate into a mixed cell population that contains low levels of Flk-1 expressing vascular progenitor cells. When isolated and re-plated onto collagen type IV, Flk-1+ cells further differentiate into PECAM1+ endothelial and SMA+ mural cells. However, the low abundance and transient nature by which Flk-1+ cells are generated during embryonic stem (ES) cell differentiation presents limitations in case large numbers of Flk-1+ cells or its derivates are to be obtained. To optimize Flk-1 progenitor induction from undifferentiated mES cells, the effects of QS11, a small organic molecule that synergistically activates canonical Wnt signalling, were investigated. In the presence of QS11 the percentage of Flk-1+ cells in differentiating cultures of mES cells increases 1.5 fold. Furthermore, QS11 enhances cell proliferation in differentiating mES cells that results in a 2 fold increase in cell numbers when Flk-1 induction is maximal. The combined effects of QS11 on differentiation and proliferation increase the efficiency by which Flk-1 progenitors can be generated by approximately 300%, thereby providing a novel tool for vascular progenitor cell production for use in fundamental research and applications such as tissue engineering.