During normal embryogenesis, human embryonic stem cells (hESCs) differentiate along different lineages in the context of complex three-dimensional tissue structures where various growth factors direct the differentiation process at different times. Embryoid bodies (EBs) are frequently used as a means to achieve specific stages of embryogenesis in vitro[1-5]. They can be formed from hESC aggregates removed from a feeder layer and cultured in suspension (termed regular EBs). EBs allow cell-cell interaction and they can be rapidly expanded to yield differentiated cells by the use of bioreactors [6,7]. Because of heterogeneous size and spontaneous differentiation of EBs into the three germ layers of the embryo including ectoderm, mesoderm and endoderm [1], it is generally difficult to control their differentiation. Vascular cells are very promising for tissue engineering applications and the treatment of cardiovascular diseases such as myocardial ischemia [22].