The term is widely used in pharmaceutical research, biotechnology, molecular biology, toxicology and medical research. For example, an in vitro study occurs when researchers test a drug on human cells in a dish in a lab.
The idea is simple. Researchers carry out research in vitro whereby they take any biological process or material and study it within a lab setting.
What is in vitro research?
In vitro research allows researchers to study desired processes in strict lab conditions without any element of variables found within a live organism.
An example of an in vitro study is cell culture. In this case, researchers will culture cells in the lab and treat them using chemicals to monitor the response of the cells. This may include changes in cell growth, protein synthesis, toxicity, or changes in a biological pathway.
Other in vitro studies can be carried out on isolated enzymes, proteins, antibodies, tissues or microorganisms. The method depends on the question under investigation.
One major benefit is control. Research scientists are able to control variables like concentration of substances, time of exposure, temperature and pH level. Hence, it becomes easier for researchers to understand the effect under some specific conditions.
For instance, in conducting research on a possible medicine, scientists may first want to check if a substance interacts with the receptors. An in vitro experiment can give useful information about this interaction before more complex testing is done.
In vivo versus in vitro
The term “in vivo” means “in the living”. It is a description of research carried out inside a living organism.
Work that is done outside the organism, in cells, tissues or other biological material is called in vitro work. In vivo research is research conducted in a living organism, such as an animal, or in which an ethically approved human participant is involved.
These two approaches give different types of information.
Researchers can also use an experiment in vitro to study a biological mechanism more closely. However, a living body is much more complex. Absorption, metabolism, distribution and excretion can process a drug to act differently in a human body.
This means that the in vitro result cannot be used as evidence of what will happen in humans.
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Why do we do in vitro studies?
In vitro methods are often used in the early stages of research. Scientists can try different compounds or conditions to see which are worth further, more detailed investigation.
They also allow us to focus on single processes of biological nature. Researchers can study a specific receptor or enzyme, pathway or cell type without the confounding factors that exist in a whole organism.
It is also advantageous for the experimenter to have control experiments. Samples can be tested in similar conditions so that results can be more easily compared.
In some areas, in vitro research can also help limit the need for animal studies. Cell-based tests and other laboratory methods may provide useful information before animal testing. “They don’t replace all kinds of animal research, but they can be an important part of the process.”
Typical examples of in vitro research
- Cell culture studies are not rare. Researchers cultivate cells in laboratory vessels and use them to study how a compound affects cell behaviour.
- Enzyme assays are used to determine if a substance affects the activity of a specific enzyme. They are often used in studies of biological mechanisms or possible medicines.
- Receptor binding studies investigate whether a particular molecule can attach to a receptor and to what degree. This work can shed light on the mechanism of action of drug candidates.
- Tissue research is performed on samples of tissue maintained in vitro, which may produce information that is not available when studying single cells.
- In toxicology, in vitro testing is also useful. The researchers may use different amounts of any particular substance on the cells and analyse the changes that take place due to that exposure.
What in vitro findings can researchers use?
A good in vitro study can tell us about biological activity, molecular interactions, toxicity, drug potency and potential mechanisms of action.
For example, in pharmaceutical research a compound is active against a particular target in an in vitro assay. This may give researchers a reason to study the compound further.
Despite that, the effects observed in a test tube may not be exactly predictable for organisms at large.
Laboratory cell culture systems do not accurately copy the systems present in a human organism either. It does not consider all the processes involved in absorption, metabolism or distribution. Cells grown outside the body may also act differently than cells in living tissue.
Thus, in vitro results are usually interpreted in the light of other evidence.
In vitro tests for drug development
In vitro testing can be used at various stages of drug research.
Early testing can identify compounds that modulate a given biological target. The researchers can then look into their potency, selectivity and effects on cells.
Further experiments could reveal whether a compound hits its intended target or causes unwanted effects in the cell.
The findings can help guide researchers as to the compounds that should be advanced to the later stages of research. In vitro testing, therefore, is an important part of drug development but only one part of the overall process.
In vitro research limitations
One of the nice things about an in vitro experiment is that it’s controlled, but that’s also a limitation.
The laboratory environment may not accurately replicate conditions inside the body. Once removed from their native environment, cells may act differently, and outcomes may differ depending on cell type, culture conditions and experimental method.
In a laboratory test the concentration of a substance may be different from that which would reach a particular tissue in a living organism.
Hence, it is important to have a suitable experimental design and appropriate controls. Researchers must understand what their model is capable of illustrating and what it is not.
Why the phrase is important?
‘In vitro’ When you see the term ‘in vitro’ used in a scientific paper or research report, it means the work was done outside of an organism, in a laboratory setting. But that alone doesn’t tell you whether a treatment will work in people.
To put it simply, in vitro is the study of biological material outside of the living organism, in controlled laboratory conditions.
“It gives researchers a way to study, in a practical way, how cells respond to compounds, how molecules interact and where a potential treatment might have an effect. These results can then be integrated with other research to develop a more complete picture of a drug, biological process or potential treatment.
Research Use Only. This glossary explains terminology used in published research. It is not medical advice and does not describe any product for human or animal use.