XTT Cytotoxicity Test, Cell Viability Test
XTT Cytotoxicity is a Ready to use assay for the biological
evaluation and screening of chemical, pharmaceutical, cosmetic compounds
or of a medical device using in vitro mammalian or animal cell
cultures. The XTT assay is preferred as an early, simple, fast and
sensitive assay. Moreover, the assays are fully in line with 3R’s -
Replace, Refine, Reduce and avoids animal testing. The kit includes a
detailed instruction for use.
Chemical compounds, pharmaceuticals, cosmetic products, natural plant
extracts or materials used for implants can have a toxic effect on
mammalian cells. There are different mechanisms of toxicity, i.e. loss
of membrane integrity, lysosomal toxicity, inhibition of protein
synthesis or interference in metabolism.
Not only for the development of pharmaceuticals, cosmetics, plant
extracts or chemicals and implants, but also for the environment it is
important to discriminate between no toxicity, negligible and strong
toxicity. For example, compounds with promising biological activity and
negligible cytotoxicity should not be ruled out, because “The dose makes
the poison", i.e. all things are poison, and nothing is without poison,
the dosage alone makes it so a thing is not a poison (Paracelsus,
1493–1541).
Several different eukaryotic and prokaryotic cell lines are used to
assess cytotoxicity. Cytotoxicity assays detect cellular or metabolic
changes associated with viable or nonviable cells. Different assays can
detect different mechanisms in cells, such as biochemical activities in
the electron transport chain, protein synthesis, lysosomal activity, or
loss of membrane integrity, which are indicative signs of living cells.
XTT or other redox dies are a valuable tool to assess quantitatively
viable cells, since dyes are only reduced by metabolic active cells.
The XTT assay is based on the cleavage of the yellow tetrazolium salt
XTT to form an orange formazan dye. The formazan dye formed from XTT is
soluble in aqueous solutions and can be monitored quantitatively by a
microplate spectrophotometer. The quantity of formazan product is
directly proportional to the number of living and respiring cells.
Most assays can be automated allowing high throughput processing.
Implants or chemicals used in implants have to be tested for
cytotoxicity according to ISO 10993.
A usual XTT cell viability assay is shortly described here: Cells are
grown in 96 well tissue culture plates and are incubated with one of the
above mentioned stain solution and test compound during 4–24 h. After
this incubation period, formazan solution is formed, which is
spectrophotometrically quantified. An increase in number of living cells
results in an increase in the OD.
Characteristics:
- The kit is sufficient to detect 1200 samples
- Includes a detailed instruction for use
- Quality controlled
- The formazan dye formed from XTT is soluble in aqueous solutions
- Can be measured with a microplate reader
- In compliance with ISO 10993
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