Passage number in mammalian cells

[Goodie]

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.

 

[DocToxyn]

Typically you would consider the freeze-thaw another passage and call it around 5-6 passages left. I think the only way you can sometimes regain lost characteristics in immortal cell lines is to re-passage the cells back through an animal by creating a cell pellet and implanting it, but this may not work for all situations. Any one done this?