Studies that are in vivo are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and plants, as opposed to a tissue extract or dead organism. This is not to be confused with experiments done in vitro, i.e., in a laboratory environment using test tubes, Petri dishes, etc. 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 and clinical trials 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, 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.
In vitro studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates. Studies conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms; however, results obtained from in vitro experiments may not fully or accurately predict the effects on a whole organism. In contrast to in vitro experiments, in vivo studies are those conducted in living organisms, including humans, and whole plants.
Electroporation, or electropermeabilization, is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs, electrode arrays or DNA to be introduced into the cell. In microbiology, the process of electroporation is often used to transform bacteria, yeast, or plant protoplasts by introducing new coding DNA. If bacteria and plasmids are mixed together, the plasmids can be transferred into the bacteria after electroporation, though depending on what is being transferred, cell-penetrating peptides or CellSqueeze could also be used. Electroporation works by passing thousands of volts across suspended cells in an electroporation cuvette. Afterwards, the cells have to be handled carefully until they have had a chance to divide, producing new cells that contain reproduced plasmids. This process is approximately ten times more effective in increasing cell membrane's permeability than chemical transformation.
In vitro toxicity testing is the scientific analysis of the effects of toxic chemical substances on cultured bacteria or mammalian cells. In vitro testing methods are employed primarily to identify potentially hazardous chemicals and/or to confirm the lack of certain toxic properties in the early stages of the development of potentially useful new substances such as therapeutic drugs, agricultural chemicals and food additives.
An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a target entity. The measured entity is often called the analyte, the measurand, or the target of the assay. The analyte can be a drug, biochemical substance, chemical element or compound, or cell in an organism or organic sample. An assay usually aims to measure an analyte's intensive property and express it in the relevant measurement unit.
A micronucleus test is a test used in toxicological screening for potential genotoxic compounds. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage and is recommended by the OECD guideline for the testing of chemicals. There are two major versions of this test, one in vivo and the other in vitro.
Phloxine B is a water-soluble red dye used for coloring drugs and cosmetics in the United States and coloring food in Japan. It is derived from fluorescein, but differs by the presence of four bromine atoms at positions 2, 4, 5 and 7 of the xanthene ring and four chlorine atoms in the carboxyphenyl ring. It has an absorption maximum around 540 nm and an emission maximum around 564 nm. Apart from industrial use, phloxine B has functions as an antimicrobial substance, viability dye and biological stain. For example, it is used in hematoxylin-phloxine-saffron (HPS) staining to color the cytoplasm and connective tissue in shades of red.
Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as malaria parasites, Rhodnius and Schistosoma digest haemoglobin and release high quantities of free heme, which is the protein component of haemoglobin. Heme is a prosthetic group consisting of an iron atom contained in the center of a heterocyclic porphyrin ring. Free heme is toxic to cells, so the parasites convert it into an insoluble crystalline form called hemozoin. In malaria parasites, hemozoin is often called malaria pigment.
The Chorioallantoic Membrane (CAM), also known as the chorioallantois, is a highly vascularized membrane found in the eggs of certain amniotes like birds and reptiles. It is formed by the fusion of the mesodermal layers of two extra-embryonic membranes – the chorion and the allantois. It is the avian homologue of the mammalian placenta. It is the outermost extra-embryonic membrane which lines the non-vascular egg shell membrane.
Chickens and their eggs have been used extensively as research models throughout the history of biology. Today they continue to serve as an important model for normal human biology as well as pathological disease processes.
A 3D cell culture is an artificially created environment in which biological cells are permitted to grow or interact with their surroundings in all three dimensions. Unlike 2D environments, a 3D cell culture allows cells in vitro to grow in all directions, similar to how they would in vivo. These three-dimensional cultures are usually grown in bioreactors, small capsules in which the cells can grow into spheroids, or 3D cell colonies. Approximately 300 spheroids are usually cultured per bioreactor.
A ligand binding assay (LBA) is an assay, or an analytic procedure, which relies on the binding of ligand molecules to receptors, antibodies or other macromolecules. A detection method is used to determine the presence and extent of the ligand-receptor complexes formed, and this is usually determined electrochemically or through a fluorescence detection method. This type of analytic test can be used to test for the presence of target molecules in a sample that are known to bind to the receptor.
In vitro to in vivo extrapolation (IVIVE) refers to the qualitative or quantitative transposition of experimental results or observations made in vitro to predict phenomena in vivo, biological organisms.
Axelopran is a drug which is under development by Theravance Biopharma and licensed to Glycyx for all indications. It acts as a peripherally acting μ-opioid receptor antagonist and also acts on κ-, and δ-opioid receptors, with similar affinity for the μ- and κ-opioid receptors and about an order of magnitude lower affinity for the δ-opioid receptor. Recent data suggests that μ-opioid antagonists have a direct effect on overall survival in patients with advanced cancer.
E-SCREEN is a cell proliferation assay based on the enhanced proliferation of human breast cancer cells (MCF-7) in the presence of estrogen active substances. The E-SCREEN test is a tool to easily and rapidly assess estrogenic activity of suspected xenoestrogens. This bioassay measures estrogen-induced increase of the number of human breast cancer cell, which is biologically equivalent to the increase of mitotic activity in tissues of the genital tract. It was originally developed by Soto et al and was included in the first version of the OECD Conceptual Framework for Testing and Assessment of Endocrine Disrupters published in 2012. However, due to failed validation, it was not included in the updated version of the framework published in 2018.
A bioassay is an analytical method to determine the concentration or potency of a substance by its effect on living animals or plants, or on living cells or tissues(in vitro). A bioassay can be either quantal or quantitative, direct or indirect. If the measured response is binary, the assay is quantal, if not, it is quantitative.
Horizontal transfer of mitochondria is the movement of whole mitochondria and mitochondrial DNA between cells. Mitochondria from donor cells are transported and incorporated into the endogenous mitochondrial network of recipient cells contributing to changes in the bioenergetics profile and in other functional properties of recipient cells. Horizontal cell-to-cell transfer of mitochondria and mitochondrial genome can occur among mammalian cells in vitro and in vivo. Mitochondrial transfer supports the exogenous replacement of damaged mitochondria, thereby rescuing mitochondrial defects. Stem cells, immortalized cells or primary cells are usually used as mitochondrial donors in most studies. These cells may transfer mitochondria to surrounding cells in their niche, thus affecting cell differentiation, proliferation, tissue homeostasis, development and ageing.
Non-invasive micro-test technology (NMT) is a scientific research technology used for measuring physiological events of intact biological samples. NMT is used for research in many biological areas such as gene function, plant physiology, biomedical research, and environmental science.
Halicin (SU-3327) is a chemical compound that acts as an inhibitor of the enzyme c-Jun N-terminal kinase (JNK). Originally, it was researched for the treatment of diabetes, but development was discontinued for this application due to poor results in testing.
Cycloheximide chase assays are an experimental technique used in molecular and cellular biology to measure steady state protein stability. Cycloheximide is a drug that inhibits the elongation step in eukaryotic protein translation, thereby preventing protein synthesis. The addition of cycloheximide to cultured cells followed by protein lysis at multiple timepoints is conducted to observe protein degradation over time and can be used to determine a protein's half-life. These assays are often followed by western blotting to assess protein abundance and can be analyzed using quantitative tools such as ImageJ.
