Cell cultivation is highly dependent on conditions. They vary for each type of cell, but usually consist of a suitable vessel with a substrate or medium that provides the necessary nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones and gases (CO2, O2) and regulate the physicochemical environment (pH buffer, osmotic pressure, temperature). Most cells require a surface or artificial substrate (adhesive or monolayer culture), while others can be freely propagated in culture medium (suspension culture). The lifespan of most cells is genetically determined, but some objects of cell cultivation have been transformed into immortal cells that will reproduce indefinitely if optimal conditions are created for this.
Definition
With the definition, everything is pretty simple. In practice, the term "cell culture" now refers to the cultivation of cells derived from multicellular eukaryotes, especially animal cells, in contrast to other types of culture. Historical development and cultivation methods are closely related to tissue culture and organ culture. Viral culture is also associated with cells as hosts for viruses.
History
The laboratory technique for obtaining and culturing cells separated from the original tissue source became more stable in the middle of the 20th century. Major breakthroughs in this area were made by scientists from Yale University.
Mid-Century Breakthrough
Initially, the production and cultivation of cells was practiced in order to find a panacea for many dangerous viruses. A number of researchers have discovered that many strains of viruses can live, flourish, and multiply on artificially grown animal cells or even whole organs that are held autonomously in special flasks. As a rule, for such tests, cells of animal organs are used, as close as possible to humans - for example, higher primates like chimpanzees. All these discoveries were made in the 1940s, when experiments on people for certain reasons were most relevant.
Methodology
Cells can be isolated from tissue for ex vivo culture in several ways. They can be easily cleaned of blood, however, only white cells are capable of growth in culture. Cells can be isolated from hard tissues by digesting the extracellular matrix using enzymes such as collagenase, trypsin or pronase before mixing the tissue to release the cells into suspension. Alternatively, pieces of tissue can be placed in growth media, and cells that grow are available for culture. This technique is known as explant culture.
Cells that are cultured directly in a subject are known as primary cells. With the exception of some derived from tumors, most primary cell cultures have a limited lifespan.
Immortal and stem cells
An established or immortalized cell line has acquired the ability to multiply indefinitely, either through a random mutation, or by intentional modification, such as artificial expression of the telomerase gene. Numerous cell lines are well known as typical cell types.
A massive culture of animal cell lines is fundamental to the production of viral vaccines and other biotechnology products. A human stem cell culture is used to expand their numbers and differentiate cells into different types suitable for transplantation. The cultivation of human cells (stem) is also used to collect molecules and exosomes released by stem cells for therapeutic use.
Relationship with Genetics
Biological products obtained using recombinant DNA (rDNA) technology in animal cultures include enzymes, synthetic hormones, immunobiological (monoclonal antibodies, interleukins, lymphokines) and anti-cancer agents. Although many simpler proteins can be obtained using rDNA in bacterial cultures, more complex proteins that are glycosylated (modified by carbohydrates) must now be made in animal cells.
An important example of such a complex protein is the hormone erythropoietin. The costs of growing mammalian cell cultures are high, so research is underway to create such complex proteins in insect cells or in higher plants. The use of individual embryonic cells and somatic embryos as a source of direct gene transfer by particle bombardment, expression of transit genes, and confocal microscopy is one of its fields of application. The cultivation of plant cells is the most common form of this practice.
Tissue culture
Tissue culture is the cultivation of tissues or cells that are separated from the body. This process is usually facilitated using a liquid, semi-solid or solid growth medium, such as broth or agar. Tissue culture usually refers to the culture of animal cells and tissues, with the more specific term used for plants - the cultivation of plant cells and tissues. The term "tissue culture" was coined by the American pathologist Montrose Thomas Burroughs.
The history of tissue culture
In 1885, Wilhelm Roux removed a section of the medullary plate of an embryonic chicken and maintained it in warm saline for several days, establishing the basic principle of tissue culture. In 1907, zoologist Ross Granville Harrison demonstrated the growth of frog embryonic cells, which would lead to the emergence of nerve cells in the environment of coagulated lymph. In 1913, E. Steinhardt, C. Israel, and R. A. Lambert grew the vaccinia virus in fragments of the guinea pig horn tissue. This was already something much more advanced than the cultivation of plant cells.
From past to future
Gottlieb Haberlandt first pointed out the possibility of culturing isolated plant tissues. He suggested that this method can determine the capabilities of individual cells through tissue culture, as well as the mutual influence of tissues on each other. As Haberland’s original statements were implemented, tissue and cell culture techniques were actively applied, leading to new discoveries in biology and medicine. His original idea, introduced in 1902, was called totipotentiality: "Theoretically, all plant cells are able to produce a complete plant." Culturing cell cultures at that time advanced dramatically.
In modern use, tissue culture usually refers to cell growth from tissue of a multicellular organism in vitro. Cell culture conditions are not very important. These cells can be isolated from the donor organism, primary cells, or an immortalized cell line. Cells are washed with a culture medium that contains the nutrients and energy sources necessary for their survival. The term "tissue culture" is often used interchangeably with cell culture.
Application
The literal meaning of tissue culture refers to the cultivation of tissue pieces, that is, to an explantation culture.
Tissue culture is an important tool for studying the biology of cells from multicellular organisms. It provides an in vitro model of tissue in a well-defined environment that can be easily manipulated and analyzed.
In animal tissue culture, cells can be grown in the form of two-dimensional monolayers (normal culture) or inside fibrous forests or gels to achieve more naturalistic three-dimensional tissue-like structures (3D culture). Eric Simon, in a 1988 NIH SBIR grant report, showed that electrospinning can be used to produce nano- and submicron-sized polymer fiber scaffolds specifically designed for use as in vitro cellular and tissue substrates.
This early use of electrically conductive fiber gratings for cell culture and tissue engineering showed that different types of cells will adhere and multiply on polycarbonate fibers. It was noted that, in contrast to the flattened morphology commonly observed in 2D culture, cells grown on stranded fibers exhibit a more rounded 3-dimensional morphology commonly observed in tissues in vivo.
The plant tissue culture, in particular, is associated with the cultivation of whole plants from small pieces of plant fibers cultivated in the medium.
Differences in models
Research in tissue engineering, stem cells, and molecular biology primarily involves growing cell cultures on flat plastic dishes. This method is known as two-dimensional (2D) cell culture and was first developed by Wilhelm Roux, who in 1885 removed part of the medullary plate of an embryonic chicken and kept it in warm saline for several days on flat glass.
From the advancement of polymer technology, modern standard plastic dishes for two-dimensional cell culture, commonly known as the Petri dish, have arisen. Julius Richard Petri, a German bacteriologist, is generally referred to in the scientific literature as the author of this invention, worked as an assistant to Robert Koch. Today, various researchers also use cultural laboratory flasks, conical and even disposable bags, such as those used in disposable bioreactors.
In addition to the culture of well-established immortalized cell lines, cells from primary explants of many organisms can be cultured for a limited period of time until sensitivity appears. Cultured primary cells have been widely used in research, as in the case of fish keratocytes in cell migration studies. At the same time, a variety of cell culture media can be used.
Plant cell cultures are usually grown as cell suspension cultures in a liquid medium or in callus cultures on a solid medium. A culture of undifferentiated plant cells and calli requires an appropriate balance of plant growth hormones auxin and cytokinin.