Cell culture
As cell culture, the cultivation of animal or plant cells in a nutrient medium outside the body is called. Cell lines are cells of a tissue that can be propagated indefinitely in the course of cell culture. There are both immortalized ( immortal ) cell lines and primary cultured cells ( primary culture ). As a primary culture, is called a non- immortalized cell culture, which was obtained directly from a tissue. Cell cultures are widely used in biological and medical research, development and production.
History
Since the early days of scientific research, efforts were made to preserve cells and tissues outside of the organism alive in order to examine them more closely so consistently can. Wilhelm Roux was the first time in 1885, embryonic chicken cells for several days to get in a saline solution at life and so to demonstrate the basic principle. In 1913, Alexis Carrel showed that cells can also grow in cell culture longer, inasmuch as they are fed and kept aseptic.
The oldest animal cell line is probably the Sticker 's sarcoma, a tumor of infectious natural origin, which originated about 200 to 2500 years ago. In the years 1951/1952 for the first time an immortal human cell line was established from a cervical carcinoma, which was known as the HeLa later. In the following decades, in particular nutrient media, growth factors and conditions have been further developed and established new cell lines. César Milstein and Georges Köhler discovered in 1975 the possibility for the formation of monoclonal antibodies by cell fusion of lymphocytes with cancer cells. Furthermore, in these years, methods for targeted insertion and expression of genes in cells, known as transfection developed.
Body cells which are not yet defined - so-called stem cells were first isolated in 1981 from an embryonic mouse blastocysts. They tend in vitro to spontaneously differentiate. This can be suppressed by factors which promote the self-renewal of the cells. Several of these substances have been identified since the late 1980s. Research in this field is currently focused on the culture and targeted differentiation of both embryonic and adult stem cells.
Expiration
The application of primary cultures can be prepared from different tissues, for example, whole embryos, or individual organs, such as skin, kidney etc. The tissue is treated with a protease, such as trypsin, which degrades the proteins that maintain the cell structure. Thus, the cells are separated. By the addition of growth factors, some types of cells can be stimulated to divide specifically.
Which an animal or human tissue, tumor cells are taken after an initial growth analyzed and selected in order to bring a large Tumorzellklon then cultured on a culture medium by analysis of surface antigens ( immunocytology ) or of the genome (PCR and sequencing). The cells can be genetically engineered as a vector by introduction of a plasmid. From the stock culture ( stock ) cells are removed and frozen in liquid nitrogen and so are being sent to other research facilities.
Most of the cells have a limited life, with the exception of a few cells derived from tumors. After a certain number of doublings, these cells go into senescence and share still. Established or immortal cell lines have acquired the ability to divide indefinitely - either through random mutation ( in tumor cells), or by selective modification ( for example, by the artificial expression of the telomerase gene).
A distinction is also adherently growing (on surface ) cells, such as fibroblasts, endothelial cells, cartilage cells, and suspension cells growing freely floating in the culture medium, such as lymphocytes. The culture conditions differ greatly between the various cultured cell lines. The various cell types prefer doing different culture media that are specifically formulated for example, the pH, the amount of amino acids or nutrients. In general, mammalian cells grown at 37 ° C with an atmosphere of 5 % CO2 in special incubators. Depending on the division rate and density of the cells, the cell aggregates are released every few days and on new vessels distributed ( " splitting" called ).
Application
Cell cultures are widely used especially in research and development. The metabolism, the pitch, and many other cellular processes can be studied in the basic research. Further cultured cells can be used as test systems, for example in studying the effect of substances on the signal transduction and the cell toxicity. In this case, the number of animal experiments is drastically reduced.
For the production of a number of biotechnology products cell cultures also have high importance. For example, monoclonal antibodies for research and therapeutic use in medicine are produced by cell culture. Although simple proteins can be produced with less expenses in bacteria and more complex proteins into the cell culture to be produced, since only here be made suitable glycosylation of the proteins. An example is erythropoietin (EPO). Many vaccines are produced in cell culture. For the development and realization of industrial cell culture processes bioreactors are used. In this case, disposable bioreactors of an increased interest in the production of biopharmaceuticals.
In the plant propagation to produce complete plants in the Herbal tissue culture from cell cultures.