By removing cells from an animal or plant, it is possible to grow them in a suitable artificial environment. A cell line or cell strain can be created from a tissue sample, or cells can be extracted directly from the tissue and disaggregated by enzymatic method or mechanical method.
Many primary or modified cell lines are suitable for micronucleus testing in vitro. The current OECD guideline does not make firm recommendations on cell type selection, but it does suggest that when evaluating chemical hazards, it is important to consider the p53 status, genetic (karyotype) stability, DNA repair capacity, and origin (rodent vs. human) of the cells chosen for testing.
These cell lines can be cultivated as monolayers or suspensions based on in vitro altered cell lines or malignant cells. During the generation period of 12 to 14 hours, these cells divide rapidly, allowing for indefinite sub-cultures to last. Because of the changed chromosome number, the cell lines may display aneuploidy or heteroploidy. Cells that have been immortalized exhibit different growth characteristics. They include HeLa cells, for instance. The cells are human epithelium that was transformed by human papillomavirus 18 from a deadly cervical cancer. (HPV18). It is easy to maintain and manage indefinite cell lines. However, they can quickly change over time.
The difference between cells and lines is that lines have escaped Hayflick's limit and are immortal. Lines are relatively easy to form for some species, particularly rodents, whereas others are difficult. Neither avian tissues nor human tissues have been successful in establishing cell lines. A cell line is considered by many cell biologists to be abnormal by definition, and it is proceeding towards becoming the equivalent of a neoplastic cell.
A successful transformation of a cell requires a number of things to happen correctly:
Primary Culture
After cells have been isolated from tissues and proliferated in the proper conditions until all of the possible substrate is occupied (i.e., confluence), they are in primary culture. Subculture (also known as passage) is the process of moving the cells to a new vessel with fresh growth media in order to allow for further development.Cell line
A cell line or subclone is referred to as the main culture after the first subculture. A degree of homogeneity in the population is achieved through the passage of the most growth-friendly cells. Cell lines formed from primary cultures have a limited lifespan (see below), and when they are passaged, the most growth-friendly cells predominate.Cell strain
When cloning or another method is used to select a subpopulation of cells from a culture, a cell strain is created. A cell strain often gains further genetic modifications after the beginning of its parent line.Finite vs Continuous Cell line
In normal cells, the cells divide only a few times before senescence occurs, a genetically controlled process; these cell lines are called finite. The process of metamorphosis can lead to immortality for some cell lines, but it can also be produced chemically or virally. Cells with the potential to divide endlessly undergo transformation and form continuous cell lines.Culture conditions
The culture conditions differ for each type of cell, but the environment in which the cells are grown always contains the necessary nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (oxygen and carbon dioxide), and also controls the physicochemical environment (pH, osmotic pressure, temperature). Cells are usually cultivated adherently or monolayer, or floating in a culture medium, although they can also be cultivated floating freely in a culture medium (suspension culture).Many primary or modified cell lines are suitable for micronucleus testing in vitro. The current OECD guideline does not make firm recommendations on cell type selection, but it does suggest that when evaluating chemical hazards, it is important to consider the p53 status, genetic (karyotype) stability, DNA repair capacity, and origin (rodent vs. human) of the cells chosen for testing.
These cell lines can be cultivated as monolayers or suspensions based on in vitro altered cell lines or malignant cells. During the generation period of 12 to 14 hours, these cells divide rapidly, allowing for indefinite sub-cultures to last. Because of the changed chromosome number, the cell lines may display aneuploidy or heteroploidy. Cells that have been immortalized exhibit different growth characteristics. They include HeLa cells, for instance. The cells are human epithelium that was transformed by human papillomavirus 18 from a deadly cervical cancer. (HPV18). It is easy to maintain and manage indefinite cell lines. However, they can quickly change over time.
Established Cell Culture
Cell lines are permanent cultures of cells which can proliferate indefinitely when given fresh medium and space.The difference between cells and lines is that lines have escaped Hayflick's limit and are immortal. Lines are relatively easy to form for some species, particularly rodents, whereas others are difficult. Neither avian tissues nor human tissues have been successful in establishing cell lines. A cell line is considered by many cell biologists to be abnormal by definition, and it is proceeding towards becoming the equivalent of a neoplastic cell.
Transformed Cell Culture
Transformation
Genetic engineering involves inserting new genes (transgenes) into one single cell of a plant.A successful transformation of a cell requires a number of things to happen correctly:
- It is necessary to deliver the gene into a cell's nucleus and insert it into chromosomes.
- It must then survive in the receiving cell.
- A selectable marker must be present on the cells and plants that contain the new gene.
- One transformed cell must develop into a full-fledged plant.
- Transgenes inserted into the chromosome at a specific location must not interfere with gene expression.
- In order for a new gene to be effective, it cannot be inserted into an existing gene in the chromosome that influences plant survival or productivity.
Applications of Cell Culture
As a powerful tool in cellular and molecular biology, cell culture provides a good model system for studying normal cell functions and biochemistry (e.g., metabolic research, aging), the effects of medicines and toxic chemicals on cells, and mutations and cancers. Biological substances (e.g., vaccines, therapeutic proteins) are also produced with it, including screening and research activities. One of the main benefits of cell culture for any of these purposes is that the results can be reproduced from a batch of clonal cells.
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