''Ex vivo'' (

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

: "out of the living") literally means that which takes place outside an

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...

. In science, ''ex vivo'' refers to

experimentation An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a ...

or measurements done in or on tissue from an organism in an external environment with minimal alteration of natural conditions. Testing the effect of compounds on skin biopsies is an example of ''ex vivo'' research, while isolating the primary cells from that biopsy and creating a 3D

cell culture Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist Montrose Thomas Burrows. This tec ...

model is an example of ''

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

'' research. Both use human tissues, but the former is a more complex and translational environment for drug testing. A primary advantage of using ''ex vivo'' tissues is the ability to perform tests or measurements that would otherwise not be possible or

ethical Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns ma ...

in living subjects. Tissues may be experimented on in many ways, including in part (e.g. cardiac contractility models using atrial pectinate muscles) or as whole organs (e.g. isolated perfused heart model). Examples of ''ex vivo'' models include: * Cardiovascular safety models using cardiac tissues or blood vessels * Inflammatory studies using skin biopsies A human skin explant with punch biopsies removed

A human skin explant with punch biopsies removed

(see figure 2) * Isolated perfused heart models * ADME/DMPK studies using the

Ussing Chamber An Ussing chamber is an apparatus for measuring epithelial membrane properties. It can detect and quantify transport and barrier functions of living tissue. The Ussing chamber was invented by the Danish zoologist and physiologist Hans Henriksen ...

system

Application of ex vivo models in drug discovery

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 b ...

, ''ex vivo'' procedures use living tissues taken from an organism and cultured in a

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physi ...

apparatus under sterile conditions. There are several specialized platform technologies designed for ''ex vivo'' pharmacological research, including Ussing chambers, organ baths and wire myographs. Experiments begin as soon as possible after tissue procurement to maintain the physiological function and viability of the samples.

Differences between ''ex vivo'' VS ''in vitro'' models

There are distinct differences between ''ex vivo'' and ''

'' ''models'' that make them more suitable for certain applications and drug development stages than others. In general, ''in vitro'' models are used at an earlier stage in development as they are higher throughput than ''ex vivo'' models. Examples of drug discovery phases where ''in vitro'' models are commonly used include target identification, validation, and lead validation. Conversely, ''ex vivo'' models are used when a test article is closer to

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

to validate preclinical data in a functioning human system e.g. lead optimization and pre-clinical safety. ''Ex vivo'' models can also be used ''after'' a drug reaches clinical trial to investigate issues that were not identified using ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and p ...

'' or ''in vitro'' studies. The main features of each approach and how they differ is summarized in the table below (table 1). Table 1: Exploring the differences between ''ex vivo'' and ''in vitro'' models for drug development.

References

Latin biological phrases Latin words and phrases Animal test conditions {{Latin-vocab-stub

Application of ex vivo models in drug discovery

Differences between ''ex vivo'' VS ''in vitro'' models

See also

References