ES cells are a high potential source for use in regenerative medicine because of their high growth capacity and differentiation-competence. Endoderm cells compose respiratory, digestive and urological organs such as thyroid, lung, liver, pancreas, intestine, prostrate, bladder. In-vitro produced Hepatocytes and pancreatic beta cells from ES cells are expected to use for the treatment of liver injury and diabetes mellitus. Our strategy is to monitor intermediate stages of in-vivo endoderm development. Increasing of intermediate stage cells growth and differentiation efficiency can improve the therapeutic cell differentiation efficiency. A higher function is expected using a differentiation system according to in vivo development. We have developed the endoderm specific induction and monitoring system to separate the Goosecoid+ Sox17+ definitive endoderm stem cells with cell surface markers CXCR4 and E-cadherin. Moreover, purified definitive endoderm stem cells can dif ferentiate into various visceral organ cells including hepatocytes. Cancer is a heterogeneous disease charac terized by tumor composing of various cell types and difference among individuals, which make it difficult to treat. Our established cell-monitoring system is so useful to identify the specific cells in heterogeneous cell population from ES cells that it can be applied as a method for analysis of heterogeneous tumor cell population in the cancer.
