Germ-Cell Culture Conditions Facilitate the Reprogramming to Produce Mouse Embryonic Stem Cells

SUMMARYThe derivation of embryonic stem-cell (ESC) lines from blastocysts is a very ineffi-cient process. Murine ESCs are thought to arise from epiblast cells that are alreadypredisposedtoaprimordial-germ-cellfate.DuringtheprocessofESCderivationfromB6D2F1hybridmice,ifwefirstculturetheembryofromthetwo-cellstageinmediumsupplementedwithLIF,weimprovethequalityoftheblastocyst.Whentheblastocystisthenculturedinagerm-linestem-cellculturemedium(GSCm),weareabletomoreefficiently (28.3%) obtain quality ESC lines that have a normal karyotype, properdegree of chimerism, and exhibit germ-line transmission when microinjected intoblastocysts.Althoughgerm-cell-specificgeneswereexpressedinallculturemediumconditions, GSCm did not shift the transcriptome towards germ-cell specification. Acorrelation wasfurther observed betweenESC derivation efficiencyand the expres-sion of some imprinted genes and retrotransposable elements. In conclusion, thecombinationofLIFsupplementationfollowedbycultureinGSCmestablishesahigherefficiency method for ESC derivation.Mol. Reprod. Dev. 2014. 2014 Wiley Periodicals, Inc.