Stable Expression System Introduction

Stable expression system can refer to a cell line that is simply stable, in that it will remain unchanged over a long time. Not a common usage of the term. A cell line by definition is pretty stable, at least most are. It can refer to a cell line that has been transfected or infected with a foreign piece of DNA that has incorporated itself into the genome of the cell.

From: https://answers.yahoo.com/question/index?qid=20101026025934AAandlo

In stable expression system, the plasmid DNA is integrated into the chromosomes, or as an episome a separate piece of nuclear DNA), and gets passed on to future generations of the cell. This is a much rarer occurrence and complex to perform, as sometimes only a portion of the plasmid gets integrated, which may not contain the gene of interest. All stable expression system transfections start out as a transient transfection, with selectable markers that are able to distinguish any cells that have successfully integrated the gene into their genome. A common method used is to co-transfect the gene of interest with another gene for antibiotic resistance, and treat the transfected cells with the antibiotic. Repeating antibiotic treatment for long-term cell cultures results in the expansion of stably-transfected cells. Linear DNA appears to be better for stable expression system, although its uptake is lower than supercoiled DNA.

From: http://www.cell-transfection.com/transient-versus-stable-transfection/