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passage number in mammalian cells


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#1 indoubt

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Posted 15 March 2005 - 01:27 PM

if a cell line has a maximum of 10 passages before it changes character and i only have done 4 passages of it and made the frozen stock of some of the cells. how many passages does this frozen stock have if i thaw it and passage it? will it be only 6 passages left or 10 passages?

thanks for any inputs.

#2 humab

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Posted 15 March 2005 - 01:32 PM

well, officially you got 6 passages left...counting down...3...2...1 - pay another 400 bucks for a fresh vial from your favourite supplier...

ever since i started working with cell lines, i have been wondering if people do it that way in real world.

now that the original question is answered...opinions?

#3 indoubt

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Posted 15 March 2005 - 02:59 PM

well, officially you got 6 passages left...counting down...3...2...1 - pay another 400 bucks for a fresh vial from your favourite supplier...

so after my frozen stock has reached the last passage number then i should get a new vial from the supplier? what if i freeze down the last passage number and keep thaw and passage it? will my results get affected?

ever since i started working with cell lines, i have been wondering if people do it that way in real world.

what do you mean? :D

#4 humab

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Posted 16 March 2005 - 12:35 AM

what do you mean?


good question.
i'm not sure what approach is right here.
from what i've seen, many people don't follow these rules too strictly. i have received cell lines from other labs often, and most of the time there wasn't even a passage count mentioned.

we check our cells frequently for the characteristics we have learned to expect, using well established routine tests. that way we ensure the cells will be able to behave as expected in other experiments.

the "official" approach might be a no-brainer in this respect, but who is willing and able to spend a huge ammount of money on an (in principle) immortal cell line all the time???

a pragmatic way would be to freeze down the cells you harvest during your first passages and use those batches as a "master bank". every now and then you restart your cultures from these low-passage-count-cells.

anyway, there is a bunch of cell lines that have been around since the 70ies - how do you think they did this??? :D

sorry if i confused you even more. but that's the way i see this. perhaps there is other opinions on this?

have fun. m

Edited by humab, 16 March 2005 - 12:36 AM.


#5 humab

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Posted 16 March 2005 - 01:41 AM

did you notice the other thread on this topic?

http://www.protocol-...?showtopic=5583


bob1 gave a really nice and detailed explanation there.

#6 indoubt

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Posted 16 March 2005 - 02:20 AM

Thanks.

So immortal cell does not die and does not change character, while mortal cell dies and changes character when passage number is high? :D

#7 fred_33

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Posted 16 March 2005 - 03:27 AM

yep....and mortal cells are delicious for cell-saling companies... and nightmare for the bank account of labs :D

#8 indoubt

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Posted 16 March 2005 - 04:25 AM

thanks.

#9 humab

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Posted 16 March 2005 - 09:56 AM

be careful. there is no law to all this (cell lines themselves are anarchists)...

of course immortal cell lines can change their character. they donīt do it that easily. it depends... on the growth conditions/handling, the cell line etc.

sorry itīs not that easy.

#10 indoubt

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Posted 18 March 2005 - 03:02 AM

be careful. there is no law to all this (cell lines themselves are anarchists)...

of course immortal cell lines can change their character. they donīt do it that easily. it depends... on the growth conditions/handling, the cell line etc.

sorry itīs not that easy.

Are all cancer cells immortal cells? Or are there only cells that express an immortal protein that become immortal cells whether they are normal cells or cancer cells? :D

Thanks.




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