Normally, biological assays are based on "population-averaged" analysis then an assumption has to be made relying on the fact that the average reflects the dominant biological process occuring within individual cells.
let's check the figure attached below. Suppose that we treat biological cells with a toxic drug X over defined time T, then we assay cell viability (using tyrpan blue then counting viable cells (intact) and dead cells (blue) under microscope) showing that around 40% cells remain viable (60% of cells are killed).
1) At what extent can population behavior reflect individual cell response?
2) Suppose that we want to measure cellular component involving in drug removal or alleviating drug effect (for example peroxidase enzyme). How can we expect the component activity?? (increase or decrease) then how the result can be interpreted??
3) How much is possible to study cell response to toxic drug at the level of individual single cell???
Hi Mohammad. It might be challenging task or not. It depends on the heterogeneity of the cells.
If you are studying the toxic effects on a clonal cell population and see a survival difference, then there is something going on. It could be epigenic or specific mutations in individual cells.
Either way, if you have a clonal population of surviving cells will make it more easy to determine the survival factor(s).
If you have a heterogeneous cell population to begin with, well, that will probably make it impossible to determine what is going on at the individual cell level.
Hi Mr. Stefansson, I am working on Tobacco Bright Yellow-2 plant cells that are firstly isolated from a callus of Nicotiana tabacum seedling in 1972. TBY-2 cells are the most widely studied and are well known typical model for plant biology research.
Although TBY-2 are described as highly homogenous, they show genetic heterogeneity. So regrading drug effect on TBY-2 cells, Does overall population response represent the meaningful behavior of an individual cell? In other words, concerning viability results we should study cell resistance to drug or cell death upon drug treatment?
I think that cell resistance and cell death due to the drug are 2 sides of the same coin.
Are the surviving cells more homogeneous than the parental cells? The same question can be asked of the dead cells.
All cells are phenotypically homogenous.What do you mean by parental cells?
If these were clonal populations with identical genotypes they would either all die or all survive the drug treatment.
The fact that some cells die and some survive points to heterogeneity in the parental cell line used for this study.
Phenotypic identity does not translate to genotypic identity.
Exactly, as I said the cells were generated from seedling callus in 1972 (Japan). Our cells were bought somewhere 5 years ago so I think that they are genetically heterogenous. So in such case should we perform dose-response study in order to shed light on drug toxicity?
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