Abstract: The present invention provides a method of isolating a lineage specific stem cell in vitro, comprising a) transfecting a pluripotent embryonic stem cell with a construct comprising a regulatory region of a lineage specific gene operably linked to a DNA encoding a reporter protein, b) culturing the pluripotent embryonic stem cell under conditions such that the pluripotent embryonic stem cell differentiates into a lineage specific stem cell and c) separating the cells which express the reporter protein from the other cells in the culture, the cell which expresses the reporter protein being an isolated lineage specific stem cell. A lineage specific stem cell can also be identified utilizing this method.