In vitro toxicology
From Wikipedia, the free encyclopedia
In vitro toxicity testing is the scientific analysis of the effects of toxic chemical substances on cultured bacteria or mammalian cells. In vitro (literally 'in glass') testing methods are employed primarily to identify potentially hazardous chemicals and/or to confirm the lack of certain toxic properties in the early stages of the development of potentially useful new substances such as therapeutic drugs, agricultural chemicals and direct food additives.
Most toxicologists believe that in vitro toxicity testing methods can be a useful, time and cost-effective supplement to toxicology studies in living animals (which are termed in vivo or "in life" methods). However, it is generally accepted that the available in vitro tests are not presently adequate to entirely replace animal toxicology tests.
In vitro assays for xenobiotic toxicity are recently carefully considered by key government agencies (e.g. EPA; NIEHS/NTP; FDA), mainly due to a societal movement to reduce the use of animals in research, and a desire to better assess human risks. There are substantial activities in using in vitro systems to advance mechanistic understanding of toxicant activities, and the use of human cells and tissue to define human-specific toxic effects.
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[edit] Main methods used in In-vitro toxicology
[edit] 96 well
With 96 wells, a dose response curve can be determined and endpoints such as
- no-observed-adverse-effect-concentration (NOAEC)
- Inhibition Concentration 50% (IC50)
- Total Lethal Concentration (TLC)
[edit] Main assays used in In-vitro toxicology
The main method of analysis is the usage of assays, each assay investigate specific endpoints such as adenosine triphosphate (ATP) content and cell viability.
[edit] MTT
MTT assay is used often in determining cell viability and has been validated for use by international organisations. MTT assay involves two steps of introducing the assay to the chemicals and then a solubilisation step to remove crystals formed during the process.
[edit] MTS
The colourimetric MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2Htetrazolium) in vitro assay is an updated version of the validated MTT method, MTS assay has the advantage of being soluble and hence no solubilisation step is required.
[edit] ATP
ATP assay has the main advantage of providing results quickly (within 15 minutes) and only requires fewer sample cells. The assay performs lysis on the cells and the following chemical reaction between the assay and ATP content of cells produces luminescence. The amount of luminescence is then measured by a luminomeneter and can be translated into number cells alive since
- ATP assay assumes alive cells still have ATP inside it.
- Luminescence level recorded is proportional to the ATP content in the sample cells
[edit] External links
- Mouse Lymphoma Assay Calculations
- CeeTox - Leading the Way In In Vitro Toxicity Testing
- Introduction to Genetic Toxicology
- Alt Web
- The Johns Hopkins Center for Alternatives to Animal Testing (CAAT)
- 3-D, Human Cell-Derived TISSUES for Tox. Testing - MatTek Corp.
- In Vitro and Alternative Methods Specialty Section
- In Vitro Phototoxicity Testing
- IdMOC system for in vitro toxicity evaluation
