High efficiency transfection of monkey kidney COS-1 cells

Summary Methods are described for achieving high efficiency transient transfection of COS-1 cells. A transfection solution of vector DNA and DEAE-dextran in phosphate buffered saline is added to the cells, followed by treatment with culture medium containing chloroquine, resulting in a maximum efficiency of about 50%. The high efficiency obtained is primarily dependent on the use of Ca²⁺- or Mg²⁺-free buffer solutions for transfection, because the addition of these ions greatly reduces efficiency. Shocking the cells with dimethylsulfoxide does not increase transfection efficiency. COS-1 cells are monkey kidney cells that have a genomic insertion of the SV40 T antigen gene, allowing plasmid expression vectors bearing an SV40 replication origin to be amplified in these cells. Therefore this transfection method is useful for optimizing transient expression of genes in a mammalian cell system.