Expression of pMGN(-4k)LacZ-neo Gene Introduced into Embryonic Stem (ES) Cells in Chimeric Mouse Fetuses

We attempted to produce chimeric mouse fetuses by using an embryonic stem (ES) cell subline, OM 3, which were transfected with pMGN(-4k)LacZ-neo transgene, and to analyze expression of the transgene in chimeric mouse fetuses. In embryonic days 11-13 (E11-13), no fetuses expressing the transgene were observed. In E14, three of 11 normal fetuses recovered showed the transgene expression. In these chimeric mouse fetuses, the regions expressing the transgene were found in a wide range of fetuses, including the temporal region of the head, trunk from neck to tail, and limbs. It was shown by histochemical analysis that these patterns of transgene expression were specific to skeletal muscles. These results indicated that OM 3 cells might be useful for analyses of mouse skeletal-myogenesis and for the development of basic techniques for skeletal muscles in regenerative medicine.