I have a simple question about cell ? - (Sep/05/2006 )

What is about "the cell passage number" in the cell tissue culture.
How to know or count that which one is cell no.1, 2, 3, ..... etc ??

and ...

what is the cell passage number which is suitable for tread in the experiment ... I read some literature they said " cell no. 6-no.9 " are suitable ... what will happen if use cell passage after 9 ... is it too old ?

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The cell passage number which is suitable for exps dependents greatly on the cellular type you're working with. In instance, for most endothelial cells you have to work at early passage (sometimes at passage 3); I know that after 6 to 9 passages they progressively dedifferentiated and loose the expression of some (important) proteins. For immortalized cell lines and most of the cancer cells, the number of passages is more less crucial.

I think the results you would obtain with cells passage after 9 (as you mentioned it) might be different (and less reliable) from those obtained with "youngest" cells.

For my primary cultures (culture of cells obtained directly from tissues), I consider that the cells I plate to begin my culture are at passage 0. After the first subcultivation, my cells are at passage 1, etc... But I'm maybe wrong.. Someone have an opinion about this?

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So the passage number refers to the number of times the current cell line has been "split" or manipulated. Common practice is that the passage is marked (for example, "2") on a tube before the cells are frozen down. When you want to thaw the cells for an experiment the cell passage now becomes passage 3 or "P3". Every time after this when you split the cells or plate a new population from this line, the passage number increases by 1. For example, after you thaw your cells (P3) and they grow you plate 4 plates. These cells are now all P4. When you take those plates and plate them into 24 well plates for an experiment they now become p5. The higher the passage number though, the less the cells behave as they would in nature. This means depending on the type of experiment you are doing, the passage can be very important. For example, if you are only using the cells to grow a pathogen the cell passage can be much higher than if you are using the cells to study the function of an endogenous protein. What type of experiment are you using the cells for?

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everytime we split the cells, we add one more to the passage number.

There is no strict rule as to which passage number is ideal. Some cell lines, one uses it for 100-150 passages and some notmore than 15-20 passages. Its cell line and experiment dependent.

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as cells may be altered after each passage it may be useful to freeze a sample after let´s say every 5th passage to have a chance to reculture a well working passage number;

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ok ... thank you every body for all suggestion. They are helping me to understand a lot

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