Fundamentals of Biochemical Engineering, Part 1 - Bailey J., Ollis D. 1989

Introduction to Microbiology
Major Cell Types
Plant and Animal Cells

Many Vaccines and other biochemicals are produced by growing animal Cells in bioreactors, i.e., by cultivating cells outside the living Organism. Recent advances in tissue culture techniques, alongside newly developed Methods for the Genetic Transformation of animal and plant cells, have opened up promising new avenues for their much broader industrial application. Tissue cells can be grown in bioreactors very similar to those used for microbial cultivation; therefore, the growth kinetics of both tissue and microbial cells, as well as the biochemical reactors employed for this purpose, will be discussed in the same chapters (Chapters 7 and 9, respectively). Below we briefly review the major Types of Higher organism cells whose cultures can be grown in technological equipment independently of the source animal or plant from which they were isolated.

If a piece of animal tissue (typically obtained by disrupting intercellular bonds) is placed in an appropriate nutrient medium, most Cell types, particularly Blood Cells, will die within a few days, weeks, or months. Other cells multiply under these conditions to form a so-called primary cell line. These cells can often be passaged—that is, transferred to a fresh nutrient medium where further Cell Division yields a secondary cell line. Certain secondary cells, which presumably withstand an indefinite number of passages, are referred to as stable, permanent, or established cell lines.

Many cell lines have been derived from Epithelial Tissues (the Skin and tissues surrounding Organs and lining Body Cavities), Connective Tissues, blood, and Lymph of various animals, including humans, hamsters, monkeys, and mice. Fig. 1.11 shows a scanning electron micrograph of an LA-9 cell, isolated from mouse fibroblasts and growing on a solid support. Examples of cell lines, their sources, and designations are listed in Table 1.3. As indicated in the table, some cell lines originate from malignant tumors (carcinomas) of various tissues. Malignant growth of BLOOD AND LYMPH cells is commonly referred to as leukemia.

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FIG. 1.11. Scanning electron micrograph of an LA-9 cell culture grown on a solid support. These cells, derived from mouse fibroblasts, are typically about 15 µm wide and 75–90 µm long. (Micrograph kindly provided by J. P. Revel.)

While some tissue cell cultures can be grown in suspension within a liquid medium, the majority of cell lines require attachment to a solid surface, which imposes severe limitations on the scale of industrial production of vaccines and other biological products based on Animal Cell Cultures. The microcarrier culture technique, which we will discuss in detail in Chapter 9, has significantly enhanced the productivity (per unit volume) of bioreactors designed for the cultivation of anchorage-dependent cell lines.

Cultures of certain plant cells can also be grown as callus (a mass of undifferentiated plant tissue on a solid nutrient medium) or as Suspensions of aggregated cells. Given that plants produce numerous commercially valuable compounds—including fragrances, pigments, Pharmaceuticals, and opiates—the future use of plant cell cultures holds considerable promise. Plant cell cultures can also serve as highly specific catalysts for a range of valuable reactions. Furthermore, they may prove useful in agriculture, for instance, in whole-Plant Regeneration. At the same time, the future large-scale APPLICATION OF PLANT cell cultures must be preceded by a more thorough study of general plant biology, as well as the specific features and limitations of plant cell cultivation processes. It should be noted that insect and other invertebrate tissue cells can also be cultivated; however, subsequent chapters addressing eukaryotic tissue cultures will be restricted to animal and plant cells.

Table 1.3. Examples of standard animal cell lines and their origins

^а The designation CCL is used by The Cell Culture Repository of the American Type Culture Collection (12301 Parklawn Drive, Rockville, Maryland 20852 USA); this Organization serves as a repository and supplier of cell lines.