A fast and efficient method for transiently transfecting ES cells: application to the development of systems for conditional gene expression

Classically, mouse embryonic stem (ES) cells are transfected by electropora tion, a method that requires a large number of cells. Here we describe a pr otocol using a liposome based transfection agent that is a very simple, rap id and cost effective way of transiently transfecting very low numbers of E S cells. We found this method very useful in screening a large number of ES clones when working with inducible expression systems in which at least tw o elements are required for regulated expression of the gene of interest. A fter stable transfection of the first component, clones can be easily and r apidly screened for expression of the gene of interest by transiently trans fecting the second component of the system using this protocol.