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Drug Assays

Those Darn Invisible Creatures

If you want to make your friends in the cell culture lab jump, just walk up behind them and shout “mycoplasma!” (What’s that? You say you have no friends in the cell culture lab? Hmm. . .)
Mycoplasma is a scary word because they’re scary little organisms. They’re bacteria, just barely, running much smaller than usual and without any sort of cell wall. They also have the tiniest genomes you’re likely to ever see – being parasitic allows them to get away with a pretty limited instruction set. They can cause diseases in humans and other animals (excellent review here), but they just love to hang out with your cultured cell lines, too.
From their (admittedly rather limited) perspective, what’s not to like? Constant temperature, lots of food, and plenty of well-taken-care-of cells to mooch off of. Problem is, once they get in there, they alter the behavior of the cells they’ve infected, and you can’t trust the results of your assays with them any more. Every cell culture lab tests for these things, and every one of them still has the occasional outbreak. It’s the price of doing business. If the cells aren’t precious, they’re tossed – if they are, there are some antibiotics that will generally kill the little creatures off, but you still have to watch things closely for a while. (If you don’t want to test them yourself, you can send samples to these guys, and they’ll do it for you).
There have been periodic mycoplasma spasms in many research areas, as various groups have found that their results are suspect due to contamination. Since the little beasts pass right through filters that will strain out normal bacteria, and can’t even be reliably seen under normal microscopy conditions in many cell cultures, a little paranoia is justified. Have you checked your cells recently?

4 comments on “Those Darn Invisible Creatures”

  1. biohombre says:

    “Outbreaks” of mycoplasma are generally due to inadequate material control. Careful screening of materials used for cell culture, as well as isolation of incoming cell lines (until verified to be clean) can provide for a lab with no outbreaks. Of course, good technique in handling of cultures is important, (can you go years without any antibiotics and maintain bacteria-free cultures?). I have worked in labs where we have successfully handled large numbers of different cell lines (40 or more) with no mycoplasma problems (on two different continents, no less). Academic labs that share cell lines and use budget sera etc. are prime sources for mycoplasma infections…

  2. Black Knight says:

    Funny you should mention this, as I whiffled about this very matter a short while ago.
    My cells are clean, by the way, and in the face of lack of interest from anyone else we’ve not done much more. But we could. . .

  3. Atompusher says:

    Yeah, I love it when people walk up behind me and say bad things. One of the chemists I work with tends to walk up behind people and blurt out random words. I was looking at analytical results of impure fractions from a horrendus prep run when I heard: SHOW-DUR! Yes, I can see the shoulder on the peak, thanks. When people are purifying compounds we constantly hear HP-er-C.

  4. Morten says:

    You forgot to mention that it generally takes months to cure cells of mycoplasma.
    Happened to a friend of mine. She got cells from some other lab and found out that they were infected. And it tooks ages to finally get them clean and then she found out that were already oncogenic… Big waste of her time. Moral of the story is: if you are gonna cure cells of mycoplasma then triple check that they actually are the cells you want. And never trust anyone.

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