What Cytotoxicity Means
Cytotoxicity means the ability of a substance or agent to damage or kill cells.
A substance that produces such an effect is called cytotoxic.
Cytotoxicity may be caused by:
- medicines and chemicals;
- toxins;
- radiation;
- nanoparticles;
- viruses;
- immune cells such as cytotoxic T cells and Natural Killer (NK) cells.
Cell damage may occur by disrupting the cell membrane, DNA, proteins, energy production or other essential cellular processes.
How Cells Are Killed
Cytotoxic agents can cause cell death mainly through:
- Apoptosis: controlled or programmed cell death in which the cell systematically shuts itself down.
- Necrosis: uncontrolled cell death caused by severe injury, often accompanied by inflammation.
- other regulated forms of cell death triggered by cellular stress.
Cytotoxicity is not always harmful. The immune system deliberately uses it to destroy virus-infected and abnormal cells, while many cancer treatments are designed specifically to kill tumour cells.
However, poor selectivity can also damage healthy cells, producing unwanted side effects.
Measurement and Applications
Scientists commonly perform cytotoxicity assays to determine whether a drug, chemical or material harms cells.
These tests may measure:
- how many cells remain alive;
- damage to cell membranes;
- changes in cell metabolism;
- signs of programmed cell death.
Cytotoxicity testing is important in:
- cancer-drug development;
- pharmaceutical safety testing;
- toxicology;
- evaluation of medical devices and biomaterials;
- nanoparticle research;
- environmental chemical testing.
An important concept is selective cytotoxicity. An effective anticancer treatment should ideally be highly toxic to cancer cells while causing minimal damage to healthy cells.
Thus, cytotoxicity is essentially a measure of how strongly an agent damages or kills living cells, making it important for both assessing toxicity and developing treatments that deliberately target unwanted cells.
