1. A method for the differentiation of mammalian pluripotent stem (PS) cells into mortal multi-lineage progenitor cells, comprising: obtaining isolated PS cells; and culturing the PS cells in the presence of hyaluronan to induce differentiation of the cells, wherein said culturing results in the differentiation of the PS cells into mortal multi-lineage progenitor cells expressing CD71, CD90, and CD44 and lacking expression of CD34 and CD45.