Firstly, it is worth nothing that all of listed assays have different sensitivity and assess other parameters, e.g. MTT (which is the most popolaur test for cytotoxocity assessment) evaluates cell viability via measurement of mitochondrium activity. Moreover, one assay is more cheaper and time-consuming than the other. On the other hand, some chemicals may react with assay component and in consequence it may leads to unreliable results...All of metioned assays are approprite for fibroblast as well as other adherent cells.

Thus, there is a good practise to perform at least two assays for cytotoxicity evaluation, what allows to obtain reliable results.

I recommend the following publications:

1) In vitro cytotoxicity assays: Comparison of LDH, neutral red, MTT and protein assay in hepatoma cell lines following exposure to cadmium chloride

George Fotakis, John A. Timbrell, Toxicology Letters, Volume 160, Issue 2, 5 January 2006, Pages 171–177

2) Comparison of four different colorimetric and fluorometric cytotoxicity assays in a zebrafish liver cell line

Stephanie K Boppcorresponding and Teresa Lettieri,BMC Pharmacol. 2008; 8: 8.

Good luck

I prefer mtt assay 

Dear Omar,

I recommend you to start your investigations with MTT test because of the following reasons: MTT is the "golden" standard for cytotoxicity evaluation, it is quick, easy, not expensive (you can perform it without kit) and reliable. You can repeat it many times with different concentrations of the compounds tested and different treatment periods. The data obtained will help you to prepare concentration-response curves, to determine non-toxic and toxic concentrations. Something more, the data obtained by MTT test will help you to fix the conditions (concentrations, treatment periods, etc) for the implementation of other methods. MTT is the first step in this direction but it is always better to study the effect of the compounds on cell viability/proliferation using more than one method, using methods with different cellular/molecular targets and mechanisms of action.

You definitely need to undertake more than one cytotoxicity assay as the endpoints will be different and there will be multiple mechanisms in place.  I agree with the others that the MTT assay is a good place to start but then use some different assays to get a handle on different pathways of damage.  You may want to consider membrane damage (LDH), and oxidative stress.  If you want to be really thorough, consider DNA damage as well if you have the facilities and the time.

thank you all.