serum storage - who is right? me or my boss? (Mar/22/2006 )
Method 1 vs. Method 2 i.e. me against my boss!!
Method 1
I was taught to thaw and maintain serum at +4°C until its complete use
Method 2
My new boss hates my method. He prefers to thaw serum directly at 37°C , aliquote it, freeze it and then, before adding each aliquote to serum free medium, thaw once again at 37°C and finally (!) filter through 0.45 and 0.2 microm syringe filters.
What do you think about it? Actually I utilize my rapid and successful method when I’m sure he cannot see me!!
Waiting for your replies,
Silvia
I thaw serum at +4° for 24 hours and then store @ 4°C of refreeze small aliquots untill use (when I would thaw them again @ 4°C or if needed soon @ 37°C).
don't know if other methods are better, but what I do works for me.
I don't ever filter it however.
Hi,
we thaw serum hat +4C over night or room temperature for several hours. Then we aliquot it and freeze again at -20 till use. For use we thaw at room temperature or +37 and add it to the medium. No difference in my opinion...
Greetings.
I was used to do it in a similar way to your boss'one...
I thaw my stock, then divided it in 5ml aliquotes (because that was the right quantity to prepare medium enough for one week) and then I kept it at 4°C untill use.
Maybe it's safer to use aliquotes instead of opening your stock bottle more and more times...
and...don't be so harsh with your boss! 
hi
i use to thaw serum at 4°, store it in aliquots at -20° until use.
But if needed urgently, i may thaw alliquot or a full bottle (if no aliquots) at 37 without seeing difference. But it's known that for proteins and tough components, a slow thaw is better.
To be totally honnest, my boss told me he didn't care.
In all the labs that i have worked in we just thaw the serum (500 ml bottle) either overnight at 4 degrees or if needed rapidly at 37 degrees and then store in 4 degrees until we use it all. Usually the serum is used up pretty fast in a few days because everyone just shares one serum bottle to add to their media. I don't know of anyone havign a problem with their cells using this method.
We thaw at 4°C a bottle of 500 mL because if we let it at room temperature or at 37°C we forget it , but if your memory is better than ours, you can thaw at 37°C, and make aliquotes.
we make 50 mL aliquotes, frozen. Once thawn, these aliquotes stay in the fridge, for few days.
Many thanks to everyone! (even if english isn't my mother tongue, you understood my doubts!!) 
As I can see, thaw rapidly at 37°C is not so forbidden, though not suggested..
I forgot to explain why he filters each aliquote once thawed: it would cut off those little crystals that didn't melt during thawing.
Believe me that it's a great waste of time and money especially if it 's optional in my opinion !!
this was my first post in this useful BioForum and it worked!!
Thanks again,
Silvia
hi,
nice too read about all our forum member's experiences in regard to serum usage for cell culture.
in my opinion,
u r boss idea is pretty nice (if u use one bottle of FCS for several months in u r group) because ur 50ml aliquotes can undergo several rounds of temparature difference treatmenst from 4C to RT or to 37C for quick thaw in many peoples hands rather full bottle. interms of filtering the FCS, i m not a real fan personally in doing that coz sometimes filter get clogged becasue of large molecular weight proteins. moreover in my experience i have not found any crystals after thawing at 37C.
where as, ur idea would be perfect if you use up ur FCS bottle in 1 or 2 months, but in this case also i would prefer to aliquote and store in 4C and finsih them one after the other rather handling whole serum bottle.
infact, both treatments works fine, it is the person who works, should convince him or herself about those two opinions.
gud luck
As I can see, thaw rapidly at 37°C is not so forbidden, though not suggested..
I forgot to explain why he filters each aliquote once thawed: it would cut off those little crystals that didn't melt during thawing.
Believe me that it's a great waste of time and money especially if it 's optional in my opinion !!
this was my first post in this useful BioForum and it worked!!
Thanks again,
Silvia
hi mya ! according to me your boss is absolutely right (sorry to say ).i totally agree with payelis view. repeated freeze thawing would destroy some of the temperature sensitive factors of the serum like growth factors etc. so thaw it once at 4 C overnight or at 37 C aliquote it and store the aliquotes at sub freezing temperatures -20 C 0r -80 C. it is well proven that proteins do degrade at 4 C with time and the degradation is less at -20 or -80 C so it is better to store at -20/ -80 C. serum being a rich medium supports many microorganisms growth, so if there is contamination by chance then there is every chance that you may loose your precious cultures in addition to loss of your efforts. remember microorganisms do grow in the refrigirator. so why take chance???? serum can with stand two thawings cos you are thawing only twice.
