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Cell culture or tissue culture is the process by which
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist
Montrose Thomas Burrows Montrose Thomas Burrows (1884 – 1947) was a US surgeon and pathologist specializing in cancer research and surgery. He was born into a Scots-Irish Presbyterian family in Halstead, Kansas. (includes photo). Along with Dr. Alexis Carrel, a ...
. This technique is also called
micropropagation Micropropagation or tissue culture is the practice of rapidly multiplying plant stock material to produce many progeny plants, using modern plant tissue culture methods. Micropropagation is used to multiply a wide variety of plants, such as th ...
. After the cells of interest have been isolated from living tissue, they can subsequently be maintained under carefully controlled conditions the need to be kept at body temperature (37 °C) in an incubator. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or rich
medium Medium may refer to: Science and technology Aviation *Medium bomber, a class of war plane * Tecma Medium, a French hang glider design Communication * Media (communication), tools used to store and deliver information or data * Medium of ...
that supplies the essential nutrients (
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
s,
carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s,
vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an Nutrient#Essential nutrients, essential micronutrient that an organism needs in small quantities for the proper functioning of its ...
s,
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
s),
growth factor A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for regu ...
s,
hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
s, and gases ( CO2, O2), and regulates the physio-chemical environment (
pH buffer A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is ...
,
osmotic pressure Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in a pure ...
,
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
). Most cells require a surface or an artificial substrate to form an adherent culture as a monolayer (one single-cell thick), whereas others can be grown free floating in a medium as a
suspension culture A cell suspension or suspension culture is a type of cell culture in which single cells or small aggregates of cells are allowed to function and multiply in an agitated growth medium, thus forming a suspension. Suspension culture is one of the t ...
. This is typically facilitated via use of a liquid, semi-solid, or solid
growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...
, such as
broth Broth, also known as bouillon (), is a savory liquid made of water in which meat, fish or vegetables have been simmered for a short period of time. It can be eaten alone, but it is most commonly used to prepare other dishes, such as soups, ...
or
agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is ...
. Tissue culture commonly refers to the culture of animal cells and tissues, with the more specific term
plant tissue culture Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. It is widely used to produce clones of a plant in a method known ...
being used for plants. The lifespan of most cells is genetically determined, but some cell culturing cells have been “transformed” into immortal cells which will reproduce indefinitely if the optimal conditions are provided. In practice, the term "cell culture" now refers to the culturing of cells derived from multicellular
eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
s, especially
animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
cells, in contrast with other types of culture that also grow cells, such as
plant tissue culture Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. It is widely used to produce clones of a plant in a method known ...
,
fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...
culture, and
microbiological culture A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagn ...
(of
microbe A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s). The historical development and methods of cell culture are closely interrelated to those of
tissue culture Tissue culture is the growth of tissues or cells in an artificial medium separate from the parent organism. This technique is also called micropropagation. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, su ...
and
organ culture Organ culture is a development from tissue culture methods of research, the organ culture is able to accurately model functions of an organ in various states and conditions by the use of the actual ''in vitro'' organ itself. Parts of an organ or ...
.
Viral culture Viral culture is a laboratory technique in which samples of a virus are placed to different cell lines which the virus being tested for its ability to infect. If the cells show changes, known as cytopathic effects, then the culture is positive. ...
is also related, with cells as hosts for the viruses. The
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: physicia ...
technique of maintaining live
cell lines An immortalised cell line is a population of cells from a multicellular organism which would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular senescence and instead can keep undergoing division. The cells ...
(a population of cells descended from a single cell and containing the same genetic makeup) separated from their original tissue source became more robust in the middle 20th century.


History

The 19th-century English physiologist
Sydney Ringer Sydney Ringer FRS (March 1835 – 14 October 1910) was a British clinician, physiologist and pharmacologist, best known for inventing Ringer's solution. He was born in 1835 in Norwich, England and died following a stroke in 1910 in Lastingham, Y ...
developed salt solutions containing the chlorides of sodium, potassium, calcium and magnesium suitable for maintaining the beating of an isolated
animal heart ''Animal Heart'' is the debut studio album by Nina Persson, singer of The Cardigans, released on February 10, 2014 through Lojinx in Europe and The End Records in North America. A video for the title track of the album was released in November 20 ...
outside the body. In 1885
Wilhelm Roux Wilhelm Roux (9 June 1850 – 15 September 1924) was a German zoologist and pioneer of experimental embryology. Early life Roux was born and educated in Jena, Germany where he attended university and studied under Ernst Haeckel. He also attended u ...
removed a section of the
medullary plate The neural plate is a key developmental structure that serves as the basis for the nervous system. Cranial to the primitive node of the embryonic primitive streak, ectodermal tissue thickens and flattens to become the neural plate. The region ante ...
of an
embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
nic
chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...
and maintained it in a warm
saline solution Saline (also known as saline solution) is a mixture of sodium chloride (salt) and water. It has a number of uses in medicine including cleaning wounds, removal and storage of contact lenses, and help with dry eyes. By injection into a vein it ...
for several days, establishing the basic principle of tissue culture. In 1907 the zoologist
Ross Granville Harrison Ross Granville Harrison (January 13, 1870 – September 30, 1959) was an American biologist and anatomist credited for his pioneering work on animal tissue culture. His work also contributed to the understanding of embryonic development. Harrison ...
demonstrated the growth of frog embryonic cells that would give rise to nerve cells in a medium of clotted
lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to ...
. In 1913, E. Steinhardt, C. Israeli, and R. A. Lambert grew
vaccinia ''Vaccinia virus'' (VACV or VV) is a large, complex, enveloped virus belonging to the poxvirus family. It has a linear, double-stranded DNA genome approximately 190 kbp in length, which encodes approximately 250 genes. The dimensions of the ...
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...
in fragments of guinea pig
cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
l tissue. In 1996, the first use of regenerative tissue was used to replace a small length of urethra, which led to the understanding that the technique of obtaining samples of tissue, growing it outside the body without a scaffold, and reapplying it, can be used for only small distances of less than 1 cm.
Ross Granville Harrison Ross Granville Harrison (January 13, 1870 – September 30, 1959) was an American biologist and anatomist credited for his pioneering work on animal tissue culture. His work also contributed to the understanding of embryonic development. Harrison ...
, working at
Johns Hopkins Medical School The Johns Hopkins University School of Medicine (JHUSOM) is the medical school of Johns Hopkins University, a private research university in Baltimore, Maryland. Founded in 1893, the School of Medicine shares a campus with the Johns Hopkins Hospi ...
and then at
Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wo ...
, published results of his experiments from 1907 to 1910, establishing the methodology of
tissue culture Tissue culture is the growth of tissues or cells in an artificial medium separate from the parent organism. This technique is also called micropropagation. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, su ...
.
Gottlieb Haberlandt Gottlieb Haberlandt (28 November 1854 – 30 January 1945) was an Austrian botanist. He was the son of European 'soybean' pioneer Professor Friedrich J. Haberlandt. His son Ludwig Haberlandt was an early reproductive physiologist now given credi ...
first pointed out the possibilities of the culture of isolated tissues,
plant tissue culture Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. It is widely used to produce clones of a plant in a method known ...
. He suggested that the potentialities of individual cells via tissue culture as well as that the reciprocal influences of tissues on one another could be determined by this method. Since Haberlandt's original assertions, methods for tissue and cell culture have been realized, leading to significant discoveries in biology and medicine. His original idea, presented in 1902, was called totipotentiality: “Theoretically all plant cells are able to give rise to a complete plant.” Cell culture techniques were advanced significantly in the 1940s and 1950s to support research in
virology Virology is the Scientific method, scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host (biology), ...
. Growing viruses in cell cultures allowed preparation of purified viruses for the manufacture of
vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...
s. The injectable
polio vaccine Polio vaccines are vaccines used to prevent poliomyelitis (polio). Two types are used: an inactivated poliovirus given by injection (IPV) and a weakened poliovirus given by mouth (OPV). The World Health Organization (WHO) recommends all chil ...
developed by
Jonas Salk Jonas Edward Salk (; born Jonas Salk; October 28, 1914June 23, 1995) was an American virologist and medical researcher who developed one of the first successful polio vaccines. He was born in New York City and attended the City College of New Y ...
was one of the first products mass-produced using cell culture techniques. This vaccine was made possible by the cell culture research of
John Franklin Enders John Franklin Enders (February 10, 1897 – September 8, 1985) was an American biomedical scientist and Nobel Laureate. Enders has been called "The Father of Modern Vaccines." Life and education Enders was born in West Hartford, Connecticut on Fe ...
,
Thomas Huckle Weller Thomas Huckle Weller (June 15, 1915 – August 23, 2008) was an American virologist. He, John Franklin Enders and Frederick Chapman Robbins were awarded a Nobel Prize in Physiology or Medicine in 1954 for showing how to cultivate poliomyelitis ...
, and
Frederick Chapman Robbins Frederick Chapman Robbins (August 25, 1916 – August 4, 2003) was an American pediatrician and virologist. He was born in Auburn, Alabama, and grew up in Columbia, Missouri, attending David H. Hickman High School. He received the Nobel Prize in ...
, who were awarded a
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
for their discovery of a method of growing the virus in monkey
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
cell cultures. Cell culture has contributed to the development of vaccines for many diseases.


Modern usage

In modern usage, "tissue culture" generally refers to the growth of cells from a tissue from a
multicellular A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- ...
organism ''in vitro''. These cells may be cells isolated from a donor organism ( primary cells) or an
immortalised cell line An immortalised cell line is a population of cells from a multicellular organism which would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular senescence and instead can keep undergoing division. The cells ...
. The cells are bathed in a culture medium, which contains essential nutrients and energy sources necessary for the cells' survival. Thus, in its broader sense, "tissue culture" is often used interchangeably with "cell culture". On the other hand, the strict meaning of "tissue culture" refers to the culturing of tissue pieces, i.e.
explant culture In biology, explant culture is a technique to organotypically culture cells from a piece or pieces of tissue or organ removed from a plant or animal. The term ''explant'' can be applied to samples obtained from any part of the organism. The extracti ...
. Tissue culture is an important tool for the study of the biology of cells from multicellular organisms. It provides an ''in vitro'' model of the tissue in a well defined environment which can be easily manipulated and analysed. In animal tissue culture, cells may be grown as two-dimensional monolayers (conventional culture) or within fibrous scaffolds or gels to attain more naturalistic three-dimensional tissue-like structures (3D culture). Eric Simon, in a 1988 NIH SBIR grant report, showed that electrospinning could be used to produced nano- and submicron-scale polymeric fibrous scaffolds specifically intended for use as ''in vitro'' cell and tissue substrates. This early use of electrospun fibrous lattices for cell culture and tissue engineering showed that various cell types would adhere to and proliferate upon polycarbonate fibers. It was noted that as opposed to the flattened morphology typically seen in 2D culture, cells grown on the electrospun fibers exhibited a more rounded 3-dimensional morphology generally observed of tissues ''in vivo''.
Plant tissue culture Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. It is widely used to produce clones of a plant in a method known ...
in particular is concerned with the growing of entire plants from small pieces of plant tissue, cultured in medium.


Concepts in mammalian cell culture


Isolation of cells

Cells can be
isolated Isolation is the near or complete lack of social contact by an individual. Isolation or isolated may also refer to: Sociology and psychology *Isolation (health care), various measures taken to prevent contagious diseases from being spread **Is ...
from tissues for ''
ex vivo ''Ex vivo'' (Latin: "out of the living") literally means that which takes place outside an organism. In science, ''ex vivo'' refers to experimentation or measurements done in or on tissue from an organism in an external environment with minimal ...
'' culture in several ways. Cells can be easily purified from blood; however, only the white cells are capable of growth in culture. Cells can be isolated from solid tissues by digesting the extracellular matrix using
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s such as
collagenase Collagenases are enzymes that break the peptide bonds in collagen. They assist in destroying extracellular structures in the pathogenesis of bacteria such as ''Clostridium''. They are considered a virulence factor, facilitating the spread of ga ...
,
trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...
, or
pronase Pronase is a commercially available mixture of proteases isolated from the extracellular fluid of ''Streptomyces griseus''. Activity extends to both denatured and native proteins leading to complete or nearly complete digestion into individual amino ...
, before agitating the tissue to release the cells into suspension. Alternatively, pieces of tissue can be placed in
growth media A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Different ...
, and the cells that grow out are available for culture. This method is known as
explant culture In biology, explant culture is a technique to organotypically culture cells from a piece or pieces of tissue or organ removed from a plant or animal. The term ''explant'' can be applied to samples obtained from any part of the organism. The extracti ...
. Cells that are cultured directly from a subject are known as primary cells. With the exception of some derived from tumors, most
primary cell culture Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...
s have limited lifespan. An established or
immortalized cell line An immortalised cell line is a population of cells from a multicellular organism which would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular senescence and instead can keep undergoing division. The cells ...
has acquired the ability to proliferate indefinitely either through random mutation or deliberate modification, such as artificial
expression Expression may refer to: Linguistics * Expression (linguistics), a word, phrase, or sentence * Fixed expression, a form of words with a specific meaning * Idiom, a type of fixed expression * Metaphorical expression, a particular word, phrase, o ...
of the
telomerase Telomerase, also called terminal transferase, is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each end of the chromosomes of most euka ...
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
. Numerous cell lines are well established as representative of particular
cell type A cell type is a classification used to identify cells that share morphological or phenotypical features. A multicellular organism may contain cells of a number of widely differing and specialized cell types, such as muscle cells and skin cells, ...
s.


Maintaining cells in culture

For the majority of isolated primary cells, they undergo the process of
senescence Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...
and stop dividing after a certain number of population doublings while generally retaining their viability (described as the Hayflick limit). Aside from temperature and gas mixture, the most commonly varied factor in culture systems is the cell
growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...
. Recipes for growth media can vary in pH, glucose concentration,
growth factors A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for regu ...
, and the presence of other nutrients. The growth factors used to supplement media are often derived from the serum of animal blood, such as
fetal bovine serum Fetal bovine serum (FBS) is derived from the blood drawn from a bovine fetus via a closed system of collection at the slaughterhouse. Fetal bovine serum is the most widely used serum-supplement for the in vitro cell culture of eukaryotic cells. Th ...
(FBS), bovine calf serum, equine serum, and porcine serum. One complication of these blood-derived ingredients is the potential for contamination of the culture with viruses or
prion Prions are misfolded proteins that have the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many other animals. It ...
s, particularly in medical
biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used b ...
applications. Current practice is to minimize or eliminate the use of these ingredients wherever possible and use human
platelet lysate Human platelet lysate (or hPL) is a substitute supplement for fetal bovine serum (FBS) in experimental and clinical cell culture. It is a turbid, light-yellow liquid that is obtained from human blood platelets after freeze/thaw cycle(s). The freeze/ ...
(hPL). This eliminates the worry of cross-species contamination when using FBS with human cells. hPL has emerged as a safe and reliable alternative as a direct replacement for FBS or other animal serum. In addition,
chemically defined media A chemically defined medium is a growth medium suitable for the in vitro cell culture of human or animal cells in which all of the chemical components are known. Standard cell culture media commonly consist of a basal medium supplemented with anim ...
can be used to eliminate any serum trace (human or animal), but this cannot always be accomplished with different cell types. Alternative strategies involve sourcing the animal blood from countries with minimum
BSE BSE may refer to: Medicine * Bovine spongiform encephalopathy, also known as mad cow disease, a neurodegenerative disease of cattle * Breast self-examination Stock exchanges * Bahrain Stock Exchange, Bahrain * Baku Stock Exchange, Azerbaijan * B ...
/ TSE risk, such as The United States, Australia and New Zealand, and using purified nutrient concentrates derived from serum in place of whole animal serum for cell culture. Plating density (number of cells per volume of culture medium) plays a critical role for some cell types. For example, a lower plating density makes
granulosa cell A granulosa cell or follicular cell is a somatic cell of the sex cord that is closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals. Structure and function In the primordial ovarian follicle, an ...
s exhibit estrogen production, while a higher plating density makes them appear as
progesterone Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the m ...
-producing
theca lutein cell The corpus luteum (Latin for "yellow body"; plural corpora lutea) is a temporary endocrine structure in female ovaries involved in the production of relatively high levels of progesterone, and moderate levels of estradiol, and inhibin A. It is t ...
s. Cells can be grown either in
suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspend ...
or adherent cultures. Some cells naturally live in suspension, without being attached to a surface, such as cells that exist in the bloodstream. There are also cell lines that have been modified to be able to survive in suspension cultures so they can be grown to a higher density than adherent conditions would allow. Adherent cells require a surface, such as tissue culture plastic or
microcarrier A microcarrier is a support matrix that allows for the growth of adherent cells in bioreactors. Instead of on a flat surface, cells are cultured on the surface of spherical microcarriers so that each particle carries several hundred cells, and the ...
, which may be coated with extracellular matrix (such as collagen and laminin) components to increase adhesion properties and provide other signals needed for growth and differentiation. Most cells derived from solid tissues are adherent. Another type of adherent culture is organotypic culture, which involves growing cells in a three-dimensional (3-D) environment as opposed to two-dimensional culture dishes. This 3D culture system is biochemically and physiologically more similar to ''in vivo'' tissue, but is technically challenging to maintain because of many factors (e.g. diffusion).


Cell culture basal media

There are different kinds of cell culture media which being used routinely in life science including the following: *
MEM Mem (also spelled Meem, Meme, or Mim) is the thirteenth letter of the Semitic abjads, including Hebrew mēm , Aramaic Mem , Syriac mīm ܡ, Arabic mīm and Phoenician mēm . Its sound value is . The Phoenician letter gave rise to the Greek mu ...
*
DMEM Minimal Essential Medium (MEM) is a synthetic cell culture medium developed by Harry Eagle first published in 1959 in ''Science'' that can be used to maintain cells in tissue culture. It is based on 6 salts and glucose described in Earle's salts i ...
*
RPMI 1640 RPMI 1640, also known as RPMI medium, is a growth medium used in cell culture. RPMI 1640 was developed by George E. Moore, Robert E. Gerner, and H. Addison Franklin in 1966 at Roswell Park Comprehensive Cancer Center (formerly known as Roswell Park ...
* Ham's f-12 * IMDM *Leibovitz L-15 *DMEM/F-12


Components of cell culture media


Typical Growth conditions


Cell line cross-contamination

Cell line cross-contamination can be a problem for scientists working with cultured cells. Studies suggest anywhere from 15 to 20% of the time, cells used in experiments have been misidentified or contaminated with another cell line. Problems with cell line cross-contamination have even been detected in lines from the NCI-60 panel, which are used routinely for drug-screening studies. Major cell line repositories, including the
American Type Culture Collection ATCC or the American Type Culture Collection is a nonprofit organization which collects, stores, and distributes standard reference microorganisms, cell lines and other materials for research and development. Established in 1925 to serve as a natio ...
(ATCC), the European Collection of Cell Cultures (ECACC) and the German Collection of Microorganisms and Cell Cultures (DSMZ), have received cell line submissions from researchers that were misidentified by them. Such contamination poses a problem for the quality of research produced using cell culture lines, and the major repositories are now authenticating all cell line submissions. ATCC uses
short tandem repeat A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome ...
(STR)
DNA fingerprinting DNA profiling (also called DNA fingerprinting) is the process of determining an individual's DNA characteristics. DNA analysis intended to identify a species, rather than an individual, is called DNA barcoding. DNA profiling is a forensic tec ...
to authenticate its cell lines. To address this problem of cell line cross-contamination, researchers are encouraged to authenticate their cell lines at an early passage to establish the identity of the cell line. Authentication should be repeated before freezing cell line stocks, every two months during active culturing and before any publication of research data generated using the cell lines. Many methods are used to identify cell lines, including
isoenzyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...
analysis, human lymphocyte antigen (HLA) typing, chromosomal analysis, karyotyping, morphology and STR analysis. One significant cell-line cross contaminant is the immortal
HeLa HeLa (; also Hela or hela) is an immortalized cell line used in scientific research. It is the oldest and most commonly used human cell line. The line is derived from cervical cancer cells taken on February 8, 1951, named after Henrietta La ...
cell line. Hela contamination was first noted in the early 1960s in non-human culture in the USA. Intraspecies contamination was discovered in nineteen cell lines in the seventies. In 1974, five human cell lines from the Soviet Union were found to be Hela. A follow-up study analysing 50-odd cell lines indicated that half had Hela markers, but contaminant Hela had hybridised with the original cell lines. Hela cell contamination from
air droplets An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog or mist, dust, forest exudates, and geyser steam. Examples of anthropogen ...
has been reported. Hela was even unknowingly injected into human subjects by
Jonas Salk Jonas Edward Salk (; born Jonas Salk; October 28, 1914June 23, 1995) was an American virologist and medical researcher who developed one of the first successful polio vaccines. He was born in New York City and attended the City College of New Y ...
in a 1978 vaccine trial.


Other technical issues

As cells generally continue to divide in culture, they generally grow to fill the available area or volume. This can generate several issues: *Nutrient depletion in the growth media *Changes in pH of the growth media *Accumulation of
apoptotic Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes includ ...
/
necrotic Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
(dead) cells *Cell-to-cell contact can stimulate cell cycle arrest, causing cells to stop dividing, known as
contact inhibition In cell biology, contact inhibition refers to two different but closely related phenomena: contact inhibition of locomotion (CIL) and contact inhibition of proliferation (CIP). CIL refers to the avoidance behavior exhibited by fibroblast-like cells ...
. *Cell-to-cell contact can stimulate
cellular differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular ...
. * Genetic and
epigenetic In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...
alterations, with a
natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
of the altered cells potentially leading to overgrowth of abnormal, culture-adapted cells with decreased differentiation and increased proliferative capacity. The choice of
culture medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Different ...
might affect the physiological relevance of findings from cell culture experiments due to the differences in the nutrient composition and concentrations. A systematic bias in generated datasets was recently shown for
CRISPR CRISPR () (an acronym for clustered regularly interspaced short palindromic repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. These sequences are derived from DNA fragments of bacte ...
and RNAi gene silencing screens, and for metabolic profiling of cancer cell lines. Using a
growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...
that better represents the physiological levels of nutrients can improve the physiological relevance of in vitro studies and recently such media types, as Plasmax and Human Plasma Like Medium (HPLM), were developed.


Manipulation of cultured cells

Among the common manipulations carried out on culture cells are media changes, passaging cells, and transfecting cells. These are generally performed using tissue culture methods that rely on aseptic technique. Aseptic technique aims to avoid contamination with bacteria, yeast, or other cell lines. Manipulations are typically carried out in a biosafety cabinet or laminar flow cabinet to exclude contaminating micro-organisms. Antibiotics (e.g. penicillin and streptomycin) and antifungals (e.g.amphotericin B and Antibiotic-Antimycotic solution) can also be added to the growth media. As cells undergo metabolic processes, acid is produced and the pH decreases. Often, a pH indicator is added to the medium to measure nutrient depletion.


Media changes

In the case of adherent cultures, the media can be removed directly by aspiration, and then is replaced. Media changes in non-adherent cultures involve centrifuging the culture and resuspending the cells in fresh media.


Passaging cells

Passaging (also known as subculture or splitting cells) involves transferring a small number of cells into a new vessel. Cells can be cultured for a longer time if they are split regularly, as it avoids the senescence associated with prolonged high cell density. Suspension cultures are easily passaged with a small amount of culture containing a few cells diluted in a larger volume of fresh media. For adherent cultures, cells first need to be detached; this is commonly done with a mixture of
trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...
-EDTA; however, other enzyme mixes are now available for this purpose. A small number of detached cells can then be used to seed a new culture. Some cell cultures, such as RAW cells are mechanically scraped from the surface of their vessel with rubber scrapers.


Transfection and transduction

Another common method for manipulating cells involves the introduction of foreign DNA by transfection. This is often performed to cause cells to gene expression, express a gene of interest. More recently, the transfection of RNAi constructs have been realized as a convenient mechanism for suppressing the expression of a particular gene/protein. DNA can also be inserted into cells using viruses, in methods referred to as transduction (genetics), transduction, infection or transformation (genetics), transformation. Viruses, as parasitic agents, are well suited to introducing DNA into cells, as this is a part of their normal course of reproduction.


Established human cell lines

Cell lines that originate with humans have been somewhat controversial in bioethics, as they may outlive their parent organism and later be used in the discovery of lucrative medical treatments. In the pioneering decision in this area, the Supreme Court of California held in ''Moore v. Regents of the University of California'' that human patients have no property rights in cell lines derived from organs removed with their consent. It is possible to fuse normal cells with an
immortalised cell line An immortalised cell line is a population of cells from a multicellular organism which would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular senescence and instead can keep undergoing division. The cells ...
. This method is used to produce monoclonal antibody, monoclonal antibodies. In brief, lymphocytes isolated from the spleen (or possibly blood) of an immunization, immunised animal are combined with an immortal myeloma cell line (B cell lineage) to produce a hybridoma which has the antibody specificity of the primary lymphocyte and the immortality of the myeloma. Selective growth medium (HA or HAT) is used to select against unfused myeloma cells; primary lymphoctyes die quickly in culture and only the fused cells survive. These are screened for production of the required antibody, generally in pools to start with and then after single cloning.


Cell strains

A cell strain is derived either from a primary culture or a cell line by the selection or cloning of cells having specific properties or characteristics which must be defined. Cell strains are cells that have been adapted to culture but, unlike cell lines, have a finite division potential. Non-immortalized cells stop dividing after 40 to 60 population doublings and, after this, they lose their ability to proliferate (a genetically determined event known as senescence).


Applications of cell culture

Mass culture of animal cell lines is fundamental to the manufacture of viral vaccines and other products of biotechnology. Culture of human stem cells is used to expand the number of cells and differentiate the cells into various somatic cell types for transplantation. Stem cell culture is also used to harvest the molecules and exosomes that the stem cells release for the purposes of therapeutic development. Biological products produced by recombinant DNA (rDNA) technology in animal cell cultures include enzymes, synthetic hormones, immunobiologicals (monoclonal antibodies, interleukins, lymphokines), and anticancer agents. Although many simpler proteins can be produced using rDNA in bacterial cultures, more complex proteins that are Glycosylation, glycosylated (carbohydrate-modified) currently must be made in animal cells. An important example of such a complex protein is the hormone erythropoietin. The cost of growing mammalian cell cultures is high, so research is underway to produce such complex proteins in insect cells or in higher plants, use of single embryonic cell and Somatic (biology), somatic embryos as a source for direct gene transfer via particle bombardment, transit gene expression and confocal microscopy observation is one of its applications. It also offers to confirm single cell origin of somatic embryos and the asymmetry of the first cell division, which starts the process. Cell culture is also a key technique for cellular agriculture, which aims to provide both new products and new ways of producing existing agricultural products like milk, Cultured meat, (cultured) meat, fragrances, and rhino horn from cells and microorganisms. It is therefore considered one means of achieving animal-free agriculture. It is also a central tool for teaching cell biology.


Cell culture in two dimensions

Research in tissue engineering, stem cells and molecular biology primarily involves cultures of cells on flat plastic dishes. This technique is known as two-dimensional (2D) cell culture, and was first developed by
Wilhelm Roux Wilhelm Roux (9 June 1850 – 15 September 1924) was a German zoologist and pioneer of experimental embryology. Early life Roux was born and educated in Jena, Germany where he attended university and studied under Ernst Haeckel. He also attended u ...
who, in 1885, removed a portion of the medullary plate of an embryonic chicken and maintained it in warm saline for several days on a flat glass plate. From the advance of polymer technology arose today's standard plastic dish for 2D cell culture, commonly known as the Petri dish. Julius Richard Petri, a German bacteriologist, is generally credited with this invention while working as an assistant to Robert Koch. Various researchers today also utilize culturing laboratory flasks, conicals, and even disposable bags like those used in single-use bioreactors. Aside from Petri dishes, scientists have long been growing cells within biologically derived matrices such as collagen or fibrin, and more recently, on synthetic hydrogels such as polyacrylamide or PEG. They do this in order to elicit phenotypes that are not expressed on conventionally rigid substrates. There is growing interest in controlling matrix stiffness, a concept that has led to discoveries in fields such as: *Stem cell self-renewal *Lineage specification *Cancer cell phenotype *Fibrosis *Hepatocyte function *Mechanosensing


Cell culture in three dimensions

3D cell culture, Cell culture in three dimensions has been touted as "Biology's New Dimension". At present, the practice of cell culture remains based on varying combinations of single or multiple cell structures in 2D. Currently, there is an increase in use of 3D cell cultures in research areas including drug discovery, cancer biology, regenerative medicine, nanomaterials assessment and basic Life-science, life science research. 3D cell cultures can be grown using a scaffold or matrix, or in a scaffold-free manner. Scaffold based cultures utilize an acellular 3D matrix or a liquid matrix. Scaffold-free methods are normally generated in suspensions. There are a variety of platforms used to facilitate the growth of three-dimensional cellular structures including scaffold systems such as hydrogel matrices and solid scaffolds, and scaffold-free systems such as low-adhesion plates, 3D cell culturing by magnetic levitation, nanoparticle facilitated magnetic levitation, and hanging drop plates. Culturing cells in 3D leads to wide variation in gene expression signatures and partly mimics tissues in the physiological states. A 3D cell culture model showed cell growth similar to that of in vivo than did a monolayer culture, and all three cultures were capable of sustaining cell growth. As 3D culturing has been developed it turns out to have a great potential to design tumors models and investigate malignant transformation and metastasis, 3D cultures can provide aggerate tool for understanding changes, interactions, and cellular signaling. 3D cell culture in scaffolds Eric Simon, in a 1988 NIH SBIR grant report, showed that electrospinning could be used to produced nano- and submicron-scale polystyrene and polycarbonate fibrous scaffolds specifically intended for use as ''in vitro'' cell substrates. This early use of electrospun fibrous lattices for cell culture and tissue engineering showed that various cell types including Human Foreskin Fibroblasts (HFF), transformed Human Carcinoma (HEp-2), and Mink Lung Epithelium (MLE) would adhere to and proliferate upon polycarbonate fibers. It was noted that, as opposed to the flattened morphology typically seen in 2D culture, cells grown on the electrospun fibers exhibited a more histotypic rounded 3-dimensional morphology generally observed ''in vivo''.


3D cell culture in hydrogels

As the natural extracellular matrix (ECM) is important in the survival, proliferation, differentiation and migration of cells, different hydrogel culture matrices mimicking natural ECM structure are seen as potential approaches to in vivo –like cell culturing. Hydrogels are composed of interconnected pores with high water retention, which enables efficient transport of substances such as nutrients and gases. Several different types of hydrogels from natural and synthetic materials are available for 3D cell culture, including animal ECM extract hydrogels, protein hydrogels, peptide hydrogels, polymer hydrogels, and 3D cell culture in wood-based nanocellulose hydrogel, wood-based nanocellulose hydrogel.


3D Cell Culturing by Magnetic Levitation

The 3D cell culturing by magnetic levitation, 3D Cell Culturing by Magnetic Levitation method (MLM) is the application of growing 3D tissue by inducing cells treated with magnetic nanoparticle assemblies in spatially varying magnetic fields using neodymium magnetic drivers and promoting cell to cell interactions by levitating the cells up to the air/liquid interface of a standard petri dish. The magnetic nanoparticle assemblies consist of magnetic iron oxide nanoparticles, gold nanoparticles, and the polymer polylysine. 3D cell culture, 3D cell culturing is scalable, with the capability for culturing 500 cells to millions of cells or from single dish to high-throughput low volume systems.


Tissue culture and engineering

Cell culture is a fundamental component of
tissue culture Tissue culture is the growth of tissues or cells in an artificial medium separate from the parent organism. This technique is also called micropropagation. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, su ...
and tissue engineering, as it establishes the basics of growing and maintaining cells ''in vitro''. The major application of human cell culture is in stem cell industry, where mesenchymal stem cells can be cultured and cryopreserved for future use. Tissue engineering potentially offers dramatic improvements in low cost medical care for hundreds of thousands of patients annually.


Vaccines

Vaccines for polio, measles, mumps, rubella, and chickenpox are currently made in cell cultures. Due to the H5N1 pandemic threat, research into using cell culture for influenza vaccines is being funded by the United States government. Novel ideas in the field include recombinant DNA-based vaccines, such as one made using human Adenoviridae, adenovirus (a common cold virus) as a vector, and novel adjuvants.


Cell Co-Culture

The technique of co-culturing is used to study cell crosstalk between two or more types of cells on a plate or in a 3D matrix. The cultivation of different stem cells and the interaction of immune cells can be investigated in an in vitro model similar to biological tissue. Since most tissues contain more than one type of cell, it is important to evaluate their interaction in a 3D culture environment to gain a better understanding of their interaction and to introduce mimetic tissues. There are two types of co-culturing: direct and indirect. While direct interaction involves cells being in direct contact with each other in the same culture media or matrix, indirect interaction involves different environments, allowing signaling and soluble factors to participate. Cell differentiation in tissue models during interaction between cells can be studied using the Co-Cultured System to simulate cancer tumors, to assess the effect of drugs on therapeutic trials, and to study the effect of drugs on therapeutic trials. The co-culture system in 3D models can predict the response to chemotherapy and endocrine therapy if the microenvironment defines biological tissue for the cells. A co-culture method is used in tissue engineering to generate tissue formation with multiple cells interacting directly.


Cell culture in microfluidic device

Microfluidics technique is developed systems that can perform a process in a flow which are usually in a scale of micron. Microfluidics chip are also known as Lab-on-a-chip and they are able to have continuous procedure and reaction steps with spare amount of reactants and space. Such systems enable the identification and isolation of individual cells and molecules when combined with appropriate biological assays and high-sensitivity detection techniques.


Organ-on-a-chip

OoC systems mimic and control the microenvironment of the cells by growing tissues in microfluidics. Combining tissue engineering, biomaterials fabrication, and cell biology, it offers the possibility of establishing a biomimetic model for studying human diseases in the laboratory. In recent years, 3D cell culture science has made significant progress, leading to the development of OoC. OoC is considered as a preclinical step that benefits pharmaceutical studies, drug development and disease modeling. OoC is an important technology that can bridge the gap between animal testing and clinical studies and also by the advances that the science has achieved could be a replace for in vivo studies for drug delivery and pathophysiological studies.


Culture of non-mammalian cells

Besides the culture of well-established immortalised cell lines, cells from primary explants of a plethora of organisms can be cultured for a limited period of time before senescence occurs (see Hayflick's limit). Cultured primary cells have been extensively used in research, as is the case of fish keratocytes in cell migration studies.


Plant cell culture methods

Plant cell cultures are typically grown as cell suspension cultures in a liquid medium or as Callus (cell biology), callus cultures on a solid medium. The culturing of undifferentiated plant cells and calli requires the proper balance of the plant growth hormones auxin and cytokinin.


Insect cell culture

Cells derived from Drosophila melanogaster (most prominently, Schneider 2 cells) can be used for experiments which may be hard to do on live flies or larvae, such as biochemistry, biochemical studies or studies using siRNA. Cell lines derived from the army worm ''Spodoptera frugiperda'', including Sf9 (cells), Sf9 and Sf21, and from the cabbage looper ''Trichoplusia ni'', High Five cells, are commonly used for expression of recombinant proteins using baculovirus.


Bacterial and yeast culture methods

For bacteria and yeasts, small quantities of cells are usually grown on a solid support that contains nutrients embedded in it, usually a gel such as agar, while large-scale cultures are grown with the cells suspended in a nutrient broth.


Viral culture methods

The culture of viruses requires the culture of cells of mammalian, plant, fungal or bacterial origin as hosts for the growth and replication of the virus. Whole wild type viruses, recombinant DNA, recombinant viruses or viral products may be generated in cell types other than their natural hosts under the right conditions. Depending on the species of the virus, infection and viral replication may result in host cell lysis and formation of a viral plaque.


Common cell lines

;Human cell lines *DU145 (prostate cancer) *H295R (adrenocortical cancer) *
HeLa HeLa (; also Hela or hela) is an immortalized cell line used in scientific research. It is the oldest and most commonly used human cell line. The line is derived from cervical cancer cells taken on February 8, 1951, named after Henrietta La ...
(cervical cancer) *KBM-7 cells, KBM-7 (chronic myelogenous leukemia) *LNCaP (prostate cancer) *MCF7, MCF-7 (breast cancer) *MDA-MB-468 (breast cancer) *PC3 (prostate cancer) *Saos-2 cells, SaOS-2 (bone cancer) *SH-SY5Y (neuroblastoma, cloned from a myeloma) *T-47D (breast cancer) *THP1 cell line, THP-1 (acute myeloid leukemia) *U87 (glioblastoma) *National Cancer Institute's 60 cancer cell line panel (NCI60) ;Primate cell lines *Vero cell, Vero (African green monkey ''Chlorocebus'' kidney epithelial cell line) ;Mouse cell lines *MC3T3 (embryonic calvarium) ;Rat tumor cell lines *GH3 (pituitary tumor) *PC12 cell, PC12 (pheochromocytoma) ;Plant cell lines *Nicotiana tabaccum cv. BY-2, Tobacco BY-2 cells (kept as cell suspension culture, they are model organism, model system of plant cell) ;Other species cell lines *Dog Madin-Darby Canine Kidney Cells, MDCK kidney epithelial *Xenopus A6 kidney epithelial *Zebrafish AB9


List of cell lines


See also

* Biological immortality * Cell culture assays * Electric cell-substrate impedance sensing * List of contaminated cell lines * List of NCI-60 Cell Lines * List of LL-100 panel Cell Lines * List of breast cancer cell lines * Microphysiometry


References and notes


Further reading

* * * * * *


External links


Table of common cell lines from Alberts 4th ed.Hypertext version of the Cell Line Data BaseMicrocarrier Cell Culture Handbook by GE Healthcare Life Sciences
- Resources including application notes and protocols to create an ideal environment for growing cells, right from the start.

- Introduction to cell culture, covering topics such as laboratory set-up, safety and aseptic technique including basic cell culture protocols and video training
Database of Who's Who in Cell Culture and Related ResearchCoriell Cell RepositoriesStrategies for Protein Purification Handbook
This webinar introduces the history, theory, basic techniques, and potential pit-falls of mammalian cell culture.
The National Centre for Cell Science
(NCCS), Pune, India; national repository for cell lines/hybridomas etc.
Public Health England
Public Health England Culture Collections (ECACC) {{DEFAULTSORT:Cell Culture Cell culture, Biotechnology Cell biology Molecular biology techniques Alternatives to animal testing