I would like to know if you can get more than 100% cell viability using MTT assays. Thanks!
Hi Gloria,
To my knowledge, the MTT assays give you some readout (OD), not a viability measurement directly. To find viability, you would need to know the OD value of a non-treated / standard / control population of cells (the theoretical 100%). Then, the ratio of the treated cells' OD value to the non-treated cells would be your viability in percent.
A few things to keep in mind:
Each cell line will metabolize the MTT reagent differently, so you cannot compare the OD values between cell lines.
Fast growing cell lines do not always metabolize MTT faster; make sure that your cells become as confluent as possible (still in exponential phase growth) if they have a low OD readout. Consider letting your cells metabolize longer according to the protocol to increase sensitivity.
Depending on the accuracy of your pipetting (of the reagents and of your cells into a plate) and on the ability of the cells to recover after plating, you can get varying values between plates or wells. This may mean that a low treatment can result in an OD value that is slightly higher than the 100%. Also, some treatments may help cells proliferate (giving you more than 100%).
Make sure that the OD values you receive from the readings fall within the limits of linearity for the particular assay reagents you are using.
Check and see if your treatments or media interact with the MTT assay development without cells (some of these reagents can form a slight color change even without a cell to metabolize them).
Hope this helps,
Quais
Yes it is possible. If you test sample cells are proliferating more than the control or are metabolizing MTT more than the control. One important point to keep in mind is that the absorbance reading should not be saturated (i.e., its intensity should not increase beyond a certain point as after that you will not be able to detect any difference between different groups. Therefore you will not detect a difference even if your test cell group is proliferation more than the control (or vice versa). This will have to optimized according to your cell type and instrument that you use for recording absorbance.
I think it is possible. Quiet recently I had run some studies and checked the viability by MTT assay. Even most of my results were > 100.
Yes, In case of cellular proliferation we can get higher percentage of cellular viability using calculation of ratio between treated cell and non-treated/standard cell OD values in percentage.
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