Question

In cell motility assays:

a. Do we need to perform a cytotoxicity assay parallel with the motility assay? Why or why not?

b. If you know the IC50 value of the compound to be tested on the motility assay, would you still need to perform the cytotoxicity assay? Why or why not?

c. Why do we use a DMSO control in cell-based drug assays? For example, do you need to include a DMSO control in every motility assay? Why or why not?

Answer 1

a. Performing a cytotoxicity assay along with motility assay will give an idea of how cell motility is affected by the toxic reagents like 'reactive oxygen species' or lethal drugs and helps to know the accuracy of the assay.

It gives exact approximation of how cell viability is affected by different factors under varying environmental conditions.

b. IC50 of a compound refers to the concentration of that compound that is appropriate to inhibit a specific biological function of a cell or kill it. So, IC50 values help to quantify the exact motility values of the cell when the experiment is supplemented with a definite amount of this compound.

Hence, If these values are known, there is no need to perform any cytotoxicity assay.

c. DMSO acts as a solvent for water-insoluble samples which are to be used in the cell-based drug assays. For instance, It is a best solvent for dissolving the formazan products formed in MTT-based assays.

DMSO has been found to have cytotoxic effects on cells in a definite concentration so using DMSO controls in motility assays will help to rule out or substract the effects caused due to DMSO present in the experimental vials and obtain only the actual motility caused due to the lethal drug.