Removal of non-viable cells from a cell suspension

Isolation of cells from a lavage of a body cavity or from the mechanical or enzymic dissociation of a tissue will inevitably render a number of cells non-viable, which must be removed prior to further processing. 

Other important scenarios are the removal of non-viable cells after electroporation and the retrieval of viable cells from a valuable line of cultured cells after an incubator failure. Non-viable cells may also release intracellular components, for example hydrolytic enzymes and DNA, into the suspension; these also need to be removed from the aqueous environment of any recovered viable cells. 

Non-viable cells, which no longer enclose an osmotic space, are significantly denser than nonviable cells and thus should be easily separated from them across a density barrier. The actual density of the non-viable cells will be partly related to that of their viable counterparts.