Studies that are ''in vivo'' (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s or cells, usually

animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a ...

, including humans, and plants, as opposed to a tissue extract or dead organism. Examples of investigations ''in vivo'' include: the pathogenesis of disease by comparing the effects of bacterial infection with the effects of purified bacterial toxins; the development of non-antibiotics, antiviral drugs, and new drugs generally; and new surgical procedures. Consequently,

animal testing Animal testing, also known as animal experimentation, animal research, and ''in vivo'' testing, is the use of animals, as model organisms, in experiments that seek answers to scientific and medical questions. This approach can be contrasted ...

and

clinical trials Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

are major elements of ''in vivo'' research. ''In vivo'' testing is often employed over ''in vitro'' because it is better suited for observing the overall effects of an experiment on a living subject. In

drug discovery In the fields of medicine, biotechnology, and pharmacology, drug discovery is the process by which new candidate medications are discovered. Historically, drugs were discovered by identifying the active ingredient from traditional remedies or ...

, for example, verification of efficacy ''in vivo'' is crucial, because ''in vitro'' assays can sometimes yield misleading results with drug candidate molecules that are irrelevant ''in vivo'' (e.g., because such molecules cannot reach their site of ''in vivo'' action, for example as a result of rapid catabolism in the liver). The English

microbiologist A microbiologist (from Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of microscopic organisms such as bacteria, algae, fungi, and some types of par ...

Professor Harry Smith and his colleagues in the mid-1950s found that sterile filtrates of serum from animals infected with '' Bacillus anthracis'' were lethal for other animals, whereas extracts of culture fluid from the same organism grown ''in vitro'' were not. This discovery of anthrax toxin through the use of ''in vivo'' experiments had a major impact on studies of the pathogenesis of infectious disease. The maxim ''in vivo veritas'' ("in a living thing here istruth") (This citation describes a setup involving two kinds of transgenic mice.) is a play on '' in vino veritas'', ("in wine here istruth"), a well-known proverb.

Levels of closeness to the natural state

Latin phrases used to describe the closeness of a wet lab experiment setup to the natural state include: * '' In natura'' ("in nature"), the exact natural state * ''In vivo'' ("in the living"), with a living being (usually the whole

, in a controlled environment) * '' Ex vivo'' ("out of the living"), with part of a living being (usually tissues, organs, or cells) * ''

In vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

'' ("in the glass"), usually either a cell culture or a mixture of sub-cellular components ( disrupted cell, purified biomolecules) Different subfields of biology have a tendency to use each word differently. Notable variations from the above include: * Toxicologists lump ''ex vivo'' into ''in vitro'': any data not obtained using a whole animal is ''in vitro''. * Molecular biologists working on single-celled organisms may refer to a living microbe culture as ''in vivo'', reserving ''in vitro'' for cell-free systems. * There are also cases of mammalian cell cultures being referred to as ''in vivo''.

Methods of use

According to Christopher Lipinski and Andrew Hopkins, "Whether the aim is to discover drugs or to gain knowledge of biological systems, the nature and properties of a chemical tool cannot be considered independently of the system it is to be tested in. Compounds that bind to isolated recombinant proteins are one thing; chemical tools that can perturb cell function another; and pharmacological agents that can be tolerated by a live organism and perturb its systems are yet another. If it were simple to ascertain the properties required to develop a lead discovered ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

'' to one that is active ''in vivo'', drug discovery would be as reliable as drug manufacturing." Studies on ''In vivo'' behavior, determined the formulations of set specific drugs and their habits in a Biorelevant (or Biological relevance) medium.

References

{{Medical research studies Latin biological phrases Animal test conditions

Levels of closeness to the natural state

Methods of use

See also

References