Dear Dr. Camilla S.A. Davan Wetton

Q1) I have noticed that the recommended supplement for the media is calf serum (not FBS) - what is the rationale for this? What are the consequences of culturing these cells in FBS?

The source of calf serum is from calves aged between 20 days and 12 months. This type of serum contains lower levels of growth factor than FBS, making it less potent for supporting cell proliferation. So, calf serum is used in those cell culture applications where the high growth factor content of FBS is not necessary.

As NIH-3T3 cells have a doubling time of around 18-20 hours, it is highly proliferative. Therefore, calf serum is preferred to FBS as the supplement for the media.

Q2) When culturing NIH-3T3 cells, does serially passaging the cells lead to any morphological changes or changes in gene expression?

Yes, it does. NIH-3T3 cells are immortalized, but they will still slowly die/ undergo senescence after many passages. So, whenever you use NIH-3T3 cells for any cell-based assay, you should try to use cells of lower passage (preferably less than P-20).

Regards,

Malcolm Nobre