[Embryonic stem cell differentiation: the role of growth factors]

In vitro differentiation of embryonic stem cells is expected as a useful means to prepare target cells for transplantation therapy. If normal and functional cells can be induced to differentiate only by adding a specific growth factor, it should be a safer and simpler method. Some of the examples showed, however, that it is necessary to follow an actual differentiation process taking place in embryogenesis to induce a specific cell lineage, so that it is difficult to selectively obtain target cells by using a single growth factor. Yet, it is also suggested that cell specification may be controlled by a specific growth factor or its combination in a simplified situation such as a single cell culture in a serum-free medium.