This is the transfection protocol used at the LBTC lab for HEK cells. The transfection reagent is PEI ([http://en.wikipedia.org/wiki/Polyethylenimine polyethylenimine]).

Please use the provided Excel sheet to calculate the volume of plasmid you should add to the cells. Replace every value in red by your own, then print the sheet out and follow the provided protocol.

The difference with CHO cells is that a different cell density is required for transfection. You also use two different mediums (one for transfection and one for growth) instead of only one.

1. Passage seed 1 day prior to transfection.

2. Prepare tubes by addition of calculated volume of DNA as a droplet at the bottom.

3. Centrifuge (1500 rpm, 3 min) the necessary volume of seed, remove conditioned medium with the pump (use a 2 ml serological pipet with a broken neck) and resuspend in necessary volume of fresh transfection medium (RPMI) to acheive the required cell density (20 mio/ml).

4. Add 0.5 mL of the cell suspension to the tube with DNA and mix orbitally.

5. Add the PEI (30 ug) to the Cell+DNA mixture as soon as possible, flick 3 times.

6. Place in the incubator at 37°C.

7. Dilute the transfections with 9.5mL of growth medium (EX-CELL 293) 3 hours after the transfection.