Molecular Biotechnology: Principles and Applications - Glick, B., Pasternak, J. 2002

Fundamentals of Molecular Biotechnology
Biological Systems Used in Molecular Biotechnology
Eukaryotic Cell Cultures

Despite all the differences between eukaryotic types, the methodological approaches to cultivating insect, plant, and mammalian Cells share a great deal in common. First, a small piece of tissue is taken from the Organism and treated with Proteolytic Enzymes that break down the Proteins of the Extracellular matrix (when working with plant cells, special enzymes are added to degrade The Cell wall). The released cells are placed in a complex nutrient medium containing Amino Acids, Antibiotics, Vitamins, salts, glucose, and growth factors. Under these conditions, the cells divide until a cellular monolayer forms on the walls of the culture vessel. If the cells are not subsequently transferred to vessels with fresh nutrient medium, growth will cease. Typically, it is possible to transfer (passages, subculturing) and maintain up to 50–100 cell generations of the initial (primary) cell culture, after which the cells begin to lose their ability to divide and die off. Cultured cells retain certain Properties of the original tissue material, making them useful for studying the Biochemical characteristics of various Tissues.

Often, certain cells in passaged primary cell cultures undergo genetic alterations that accelerate their growth. Cell cultures that acquire selective advantages in this process become capable of unlimited growth in vitro and are referred to as established cell lines. Some cell lines retain the essential biochemical properties of the parent cells, while others do not. Most cells capable of unlimited growth exhibit significant Chromosomal aberrations, specifically an increase in the number of certain Chromosomes and the loss of others. In molecular biotechnology, established cell lines are sometimes utilized for propagating Viruses and expressing proteins encoded by cloned DNA sequences. Furthermore, they are employed for the large-scale production of Vaccines and recombinant proteins.