Principles and Strengths of In Vitro Testing

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Principles of In Vitro Testing

In vitro is the Latin term for “in glass,” meaning that the testing is performed in a container that is outside of a living organism. This testing uses cell-based biological models instead of animals or humans. In vitro efforts help fulfil the FDA’s “3Rs approach” to replace, reduce, and/or refine animal testing.

Replace

Develop and explore tests that replace the need for animal models.

Reduce

Minimize the number of animal models in experimentation.

Refine

Reduce the suffering and stress of laboratory animals and improve their wellbeing.

In Vitro model systems can be specified to the test sample’s intended use. 2D cell cultures are grown rapidly for high-throughput or multi-sample analysis with minimized variation between treatments. Cell cultures can also be made into 3D tissue models. These models contain differentiated cell layers to physiologically represent complex tissues and evaluate specific endpoints. Using specific geometries, in vitro cell culture models can be used to evaluate simple and complex biological responses.

To assess different biological endpoints, various forms of analytical methods may be implemented. Measurable responses of the in vitro models include cell death, growth inhibition, genetic alterations, changes in surface marker expression and altered metabolism.

Technical Specifications

Cytotoxicity
- Qualitative evaluation of cell cultures under a microscope
- Quantification of cell morphology and growth via automated cytotoxicity scoring
- Quantification using a cell viability reagent, measured by a spectrophotometer
Irritation
- Quantification using a cell viability reagent, measured by a spectrophotometer

Strengths of In Vitro Testing

Rapid results
Suitable for high throughput testing
Economically and ethically favorable compared to animal testing
Minimized presence of biological variables
3D tissues results include the effects of cell-cell interaction
Several endpoints can be measured
Customization of study details during early-stage sample development

Limitations of In Vitro Testing

Not all models account for the impact of complex physiological systems such as hormones and immunity
Some in vitro models for biological endpoint assessment may not be accepted by all regulatory bodies
Cannot identify mechanisms that lead to adverse biological results without further testing or chemical characterization

Learn more about the EAG In Vitro Biocompatibility Laboratory.