Each month we will give a tip on how to improve your results, sourced either from the literature or our own research.
Shelf Life & Storage of Media
Embryo production media is a perishable product that requires cold storage. Environmental factors that affect a media’s shelf life are light (radiation) and oxygen, along with the media’s composition. The more ‘complex’ in formulation, the more likely that oxidative damage can occur over time.
When bottling media, one of the keys to prolonging shelf life is minimising the amount of air (oxygen) that is present. Vacuum packing or inert gassing (we use nitrogen) are ways to prolong stored media immediately after manufacture. But once a bottle is open and exposed to air again (even if still kept at 4 – 8C), how long will it last? We have studied this extensively and found that our base medium has a 4-week usable life (serum-free), which is why we recommend using before this time.
But how long can you keep stored medium? It will really depend on the breakdown rates of individual components, and this is dependent on composition. This breakdown may be greatly accelerated once the medium is opened, if it is ‘aged’ from storing. There is no doubt that “fresh is best”.
In a previous “Tip of the Month”, we discussed that serum (or serum substitutes) may be added to reduce the variability in results. Adding serum will also help to “cover-up” some of the degradation occurring in media over time. Personally, I am sceptical of claims of 12-month or longer stored media shelf-life in serum-free media. I would want to see molecular fingerprinting of the stability of the media after that length of storing.
We are researching a new fingerprinting method that will allow us to provide that quality assurance. In the meantime, we are confident of a 3-month shelf-life of our N2-gassed media.
For more information on this month’s tip, contact firstname.lastname@example.org