Cell viability is a determination of living or dead cells, based on a total cell sample. Viability measurements may be used to evaluate the death or life of cancerous cells and the rejection of implanted organs. In other applications, these tests might calculate the effectiveness of a pesticide or insecticide, or evaluate environmental damage due to toxins.
Since everything living is made up of cells, cell viability counts have a tremendous number of applications. Testing for it usually involves looking at a sample cell population and staining the cells or applying chemicals to show which are living and which are dead. There are numerous tests and methods for measuring this.
When a sample is stained with various dyes or treated with chemicals, it is then subject to microscopic examination to evaluate cell viability. These measurements can be used to evaluate the effectiveness or lack thereof of certain treatments to cells.
The dyes or testing measurements used for determining cell viability are frequently called reagents. These are substances designed to provoke chemical reactions. When reagents are applied to cells, they may perform several actions, which allow scientists to examine cells in many different ways. Sometimes reagents are tested merely to show how they may affect the cells themselves, thus giving scientists information on which reagents should be avoided in order to not corrupt testing.
Cell viability may also be examined in a population or certain risk group to further understand the growth of cells. This is particularly the case with cancerous cells in human and animal populations. A viability analysis can give researchers information about the ways in which cancers grow, act, and react to treatment. These statistics can better inform treatment or help doctors give patients more accurate statistics on outcomes of particular types of cancers.
Another example of viability testing in medicine is the analysis of cells in populations where cells are routinely destroyed. For example, autoimmune conditions can attack normal and healthy cells, causing a cell viability test to yield very few living cells. Evaluation of cell viability in people with autoimmune disease may help determine progress of a disease or change treatment goals and options.