An important aspect of any biotechnological processes is the culture of animal cells in artificial media. These animal cells in culture are used in recombinant DNA technology, genetic manipulations and in a variety of industrial processes. Now-a -days it has become possible to use the cell and tissue culture in the areas of research which have a potential for economic value and commercialization. The animal cell cultures are being extensively used in production of vaccines, monoclonal antibodies, pharmaceutical drugs, cancer research, genetic manipulations etc. Animal cells e.g. egg cells are used for multiplication of superior livestock using a variety of techniques like cloning of superior embryonic cells, transformation of cultured cells leading to the production of transgenic animals. The animal cells are also used in vitro fertilization and transfer of embryos to surrogate mothers. Hence the establishment and maintenance of a proper animal culture is the first step towards using them as tools for biotechnology. HISTORY OF ANIMAL CELL CULTURE
It was Jolly, who (1903) showed for the first time that the cells can survive and divide in vitro. Ross Harrison, (1907) was able to show the development of nerve fibres from frog embryo tissue, cultured in a blood clot. Later, Alexis Carriel (1912) used tissue and embryo extracts as cultural media to keep the fragments of chick embryo heart alive. In the late 1940s, Enders, Weller and Robbins grew poliomyelitis virus in culture which paved way for testing many chemicals and antibiotics that affect multiplication of virus in living host cells. The significance of animal cell culture was increased when viruses were used to produce vaccines on animal cell cultures in late 1940s. For about 50 years, mainly tissue explants rather than cells were used for culture techniques, although later after 1950s, mainly dispersed cells in culture were utilized. In 1966, Alec Issacs discovered Interferon by infecting cells in tissue culture with viruses. He took filtrates from virus infected cells and grew fresh cells in the filtered medium. When the virus was reintroduced in the medium, the cells did not get infected. He proposed that cells infected with the virus secreted a molecule which coated onto uninfected cells and interfered with the viral entry. This molecule was called “Interferon”. Chinese Hamster Ovary (CHO) cell lines were developed during 1980s. Recombinant erythropoietin was produced on CHO cell lines by AMGEN (U.S.A.). It is used to prevent anaemia in patients with kidney failure who require dialysis. After this discovery, the Food and Drug Administration (U.S.A) granted the approval for manufacturing erythropoietin on CHO cell lines. In 1982, Thilly and co-workers used the conventional conditions of medium, serum, and O2 with suitable beads as carriers and grew certain mammalian cell lines to densities as high as 5x106 cells/ml. A lot of progress has been also made in the area of stem cell technology which will have their use in the possible replacement of damaged and dead cells. In 1996, Wilmut and co-workers successfully produced a transgenic sheep named Dolly through nuclear transfer technique. Thereafter, many such animals (like sheep, goat, pigs, fishes, birds etc.) were produced. Recently in 2002, Clonaid, a human genome society of France claimed to produce a cloned human baby named EVE. For animals, if the explant maintains its structure and function in culture it is called as an ‘organotypic culture’. If the cells in culture reassociate to create a three dimensional structure irrespective of the tissue from which it was derived, it is described as a ‘histotypic culture’. WHAT IS ANIMAL CELL CULTURE ?
Cell culture is the complex process by which cells are grown under controlled conditions, generally outside of their natural environment. In practice, the term "cell culture" now refers to the culturing of cells derived from multi-cellular eukaryotes,...
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