how to cryopreserve HepG2 cells at -80 degrees? - (Feb/26/2008 )

Hi, I'm trying to cryopreserve HepG2 cells for later use, but in this new institution I work at, there's no liquid nitrogen. All we have is a -20 freezer and a -80 freezer. Does anyone know if and how and for how long I can cryopreserve the cells under such conditions?
Would really be grateful for quick advice.
Thanks,
Hanni, Cairo

Hello,

Bearer's idea is the best. But if you don't have it, you can do the following:

put the vials immediately on ice for a few minutes to cool.
keep them at -20C for 1hr.
Put them to -80.

I usually skip the 2nd step, because I use the polystirol (or whatever it is made of, it is a white foamy, spongy material) case of 15-ml centrifuge tubes. I put the vials in the 'wells' of this and put them at -80. The thick polystrirol surrounding the vials helps them cool down slowly.

I've got no HepG cells, mine survived for ~4 months, but after 6 months, they usually are no longer viable.

-80'C is the next best thing to liquid nitrogen.

freeze down as normal (as described above), and keep them in the -80.

V

i used to wrapped my vials in thick cotton wool and aluminium foil.
store at -80C for overnight, then transfer to liquid N2.
But i think you can just store in -80C if you don't have liquid N2.

Yes, -80C is okay for a few months (one of the stickies in the forums talks about cryopreservation). I usually use a Mr. Frosty (from Nalgene) - it's a container filled with isopropanol, helps slow down the freezing in the -80C fridge. Or if all the Mr. Frosties are in use and I need to freeze, my makeshift Mr. Frosty is the styrofoam thing (from 15ml conical tubes)...cut it in half and it makes a top/bottom; spray one with lots of ethanol and then wrap it up, seems to work okay.

Cells survive within a few months. Longer than that is not really possible.