Cell viability (NPO ontology): Viability of a cell to proliferate, grow, divide, or repair damaged cell components.
Cell proliferation (http://www.biology-online.org/dictionary/Cell_growth):
Definition
noun
(1) The increase in cytoplasmic volume, as in cell development and cell reproduction.
(2) The increase in size or population of cells, as in mitosis.
There is an overlap between these two concept. As a QSAR developer we have to be precise about the endpoint we are going to model. Your help will be appreciated.
Regards,
Antonio
Hi Antonio. One definition is actually a sub-set of the other.
i.e. not all viable cells proliferate, but all proliferating cells are viable.
When cell biologists (such as myself) refer to "viability" they are referring to a cell which is a) alive & healthy (in that it's cytoplasmic membrane is intact - google: "Trypan blue exclusion" b) the cell generally does not express markers of "cell death" or "apoptosis" such as Annexin V positivity (i.e. the phosphotidyl serine in the cytoplasmic membrane is on the inner surface of the membrane and not on it's outer surface).
At least these are the "working definitions" used in cell biology.
I hope this helps,
Gary
There is no a real differences between the two terms when you work pratically. The difference is due to a technical feaures in my opinion. In biology and toxicology, an assay provides a unique response to a single questions. Let me explain taking MTT and LDH as examples. MTT assay is used to investigate cell proliferation beacuse it measure the "numer" of cell able to metabolize the dye forming a formazan salt. It is obvious that metabolizing cells are viable and so worldwide the MTT assay is considered a viability assay even if it measure cells with metabolic activity in reality. so it can be considered as indirect tool. On the other hand LDH is released only by cells with membrane damage (so they probably die) and so LDH assay can reveale cytotoxicity. It is a direct assay for cytotoxicity and often it is used also as indirect assay for viability.
The MTT question is "how many metabolic active cells there are in my weels?".
The LDH question is "How many damaged cells I have?".
Every assay provide an answer. But if you want to quantify apples you have to use an "apple counter"... in other terms.... in toxicology terms cells viability and cell proliferation can be considere the same things, expecially when you have a lot of samples and MTT is faster than counts with trypan blue... (that is a cytotoxicity assays because it stain non viable cells).
I could be more "useful" in Italian. Antoni owrite me an email.
Hello Antonio,
I would say similar to Gary that a cell, which is alive or viable, not necessarily proliferate (reproduce itself), e.g. it may be inhibited by space limitation (contact inhibition when 100% confluent). And of course, a proliferating cell has to be viable.
To differentiate this analytically is more complicate.
Some tests detect metabolic activity, e.g. MTT or Neutral Red uptake. Positive acting cells are viable (metabolically active) but not necessarily proliferating, e.g. when you added a slightly toxic substance (sometimes due to the stress they are even more active then control cells but not proliferating). When the cells are not perturbed and inhibited by space-limitation these tests are used to determine cell proliferation.
Other tests (e.g. Trypan blue, LDH-release, PI) detect membrane damage, typical for necrotic cells. Positive cells have compromised cell membranes and (probably) will die or are already dead.
Cells may also die by apoptosis - those are negative in necrosis test, but positive in apoptosis tests (e.g. Annexin V, Caspase activation, DNA-laddering).
Peter
To me these are two different types of assays which measure two different qualities of cells. Viability is live or dead?
Proliferation is just live or further going into next stage which is division.
Its like a person is present on work (live) or not (dead), if present on work, is he actually performing a task or just present and doing nothing.
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