Improving electrotransfection efficiency by post-pulse centrifugation

We have demonstrated that the viability of electrotransfected adherent CHO and suspended NK-L, K-562, L1210 and MC2 cells is improved if pelleting by centrifugation is performed immediately after pulsing. The protection effec t on cell viability is cell line- and pellet thickness-dependent. For formi ng CHO cell pellets, centrifugation force (300-13000 g) and duration are no t crucial; about five to 10 cell layers in the pellet provide the optimal p rotection effect. NK-L, K-562, L1210 and MC2 cell pellets are optimally for med by centrifugation at 13 000 g in an Eppendori desktop centrifuge. Pelle ting improves the cell viability over the whole range of the NK-L, K-562, L 1210 and MC2 cell concentrations studied When this pelleting method is appl ied to load CHO cells with FITC-dextran (41 000 MW), not only is the succes s rate close to 100%, but the growth rate is similar to the control, which is far better than the conventional electroporation method Furthermore, the transfection efficiency of the five cell lines in pellet is significantly higher than that in suspension.