A laboratory rat with a brain implant, that was used to recordin vivo neuronal activity
Studies that arein vivo (Latin for "within the living"; often notitalicized in English[1][2][3]) are those in which the effects of various biological entities are tested on whole, livingorganisms orcells, usuallyanimals, includinghumans, and plants, as opposed to atissue extract or dead organism.
Examples of investigationsin vivo include: thepathogenesis of disease by comparing the effects ofbacterial infection with the effects of purifiedbacterial toxins; the development of non-antibiotics, antiviral drugs, and new drugs generally; and new surgical procedures. Consequently,animal testing andclinical trials are major elements ofin vivo research.In vivo testing is often employed overin vitro because it is better suited for observing the overall effects of an experiment on a living subject. Indrug discovery, for example, verification of efficacyin vivo is crucial, becausein vitro assays can sometimes yield misleading results with drug candidate molecules that are irrelevantin vivo (e.g., because such molecules cannot reach their site ofin vivo action, for example as a result of rapidcatabolism in the liver).[4]
The Englishmicrobiologist ProfessorHarry Smith and his colleagues in the mid-1950s found that sterile filtrates of serum from animals infected withBacillus anthracis were lethal for other animals, whereas extracts of culture fluid from the same organism grownin vitro were not. This discovery ofanthrax toxin through the use ofin vivo experiments had a major impact on studies of the pathogenesis of infectious disease.
The maximin vivo veritas ("in a living thing [there is] truth")[5] is a play onin vino veritas, ("in wine [there is] truth"), a well-known proverb.
Latin phrases used to describe the closeness of awet lab experiment setup to the natural state include:
In natura ("in nature"), the exact natural state[6]
In vivo ("in the living"), with a living being (usually the wholeorganism, in a controlled environment)[7]
Ex vivo ("out of the living"), with part of a living being (usually tissues, organs, or cells)[8][9][7]
In vitro ("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 lumpex vivo intoin vitro: any data not obtained using a whole animal isin vitro.[10][11]
Molecular biologists working on single-celled organisms may refer to a living microbe culture asin vivo, reservingin vitro forcell-free systems.[12][13]
There are also cases of mammalian cell cultures being referred to asin vivo.[14][15]
According to ChristopherLipinski 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 discoveredin vitro to one that is activein vivo, drug discovery would be as reliable as drug manufacturing."[16] Studies onIn vivo behavior, determined the formulations of set specific drugs and their habits in a Biorelevant (or Biological relevance) medium.[17]
^Quintana-Murci, L.; Alcaïs, A.; Abel, L.; Casanova, J. L. (2007). "Immunology in natura: Clinical, epidemiological and evolutionary genetics of infectious diseases".Nature Immunology.8 (11):1165–1171.doi:10.1038/ni1535.PMID17952041.
^Griffiths, John R. (2022). "Magnetic resonance spectroscopy ex vivo: A short historical review".NMR in Biomedicine.35 (4) e4740.doi:10.1002/nbm.4740.PMID35415860.
^Toxicity, National Research Council (US) Subcommittee on Reproductive and Developmental (2001)."Experimental Animal and In Vitro Study Designs".Evaluating Chemical and Other Agent Exposures for Reproductive and Developmental Toxicity. National Academies Press (US).
