insulin stability - (Aug/21/2006 )

Hi,
Could you tell me how long insulin can be stable in culture media?
I usually add 10microgram/ml insulin to media, and then filtration.
Thank you!

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At 37 oC, insulin is stable (active) for 10-14 hr. However, that depends on other issues for example: the cell type. Insulin receptor expression on cell surface changes from cell to cell and with cell differentiation. Also it's somewhat tied up with IGF-1R expression.

Important thing to know is insulin activates intracellular signaling within 5 min and, generally, reaches saturation in 15 min. Therefore, one generally doesn't need to worry about long term stability.

I don't know your experimental set-up but as much I know, 10 ug/ml (~1.8 uM) is a very high concentration for in-vitro cell culture studies. Generally, it's used at 1-10nM. At 100nM & above, it cross-activates IGF-1R. Also few articles states that very high concentration of insulin can be apoptotic to cells.

Generally, insulin stock solution (in water or PBS) should be stored in -80 oC and should be added directly to the cells in culture. If you are adding insulin to the stock culture media and storing at 4 oC, it may not be stable for long time.

Hope this helps.

-KF

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