Isolation of Embryonic Fibroblasts and Their Use in the In Vitro Characterization of Gene Function

The use of primary-embryo-derived fibroblasts and established cell lines derived from them has played an important role in the characterization of gene function in knockout and overexpression transgenic mice. This is for several reasons. First, these have been widely used for a variety of applications including the elucidation of molecular mechanisms and analyses of growth, senescence, transformation, apoptosis, and differentiation. These cells are also susceptible to infection and trans-fection with expression constructs. Furthermore, primary embryo fibroblasts are one of the first cell lines available during a gene knockout experiment, as heterozygous mice can be mated and pregnant mice killed as early as d 12 of gestation without waiting for pups to be born. Also, if the gene modification results in lethality late (i.e., >d 12) in the fetal period, then an analysis of the “phenotype” or of gene function could still be undertaken at the cell biological or molecular level using the embryonic fibroblast cells.