Biopharmaceutical proteins protein secretion

As indicated in Table 2.1, most of the promoters used in plant tissue culture have been based on the constitutive cauliflower mosaic virus (CaMV) 35S promoter. In contrast, inducible promoters have the advantage of allowing foreign proteins to be expressed at a time that is most conducive to protein accumulation and stability. Although a considerable number of inducible promoters has been developed and used in plant culture applications, e.g. [32-37], the only one to be applied thus far for the production of biopharmaceutical proteins is the rice a-amylase promoter. This promoter controls the production of an a-amylase isozyme that is one of the most abundant proteins secreted from cultured rice cells after sucrose starvation. The rice a-amylase promoter has been used for expression of hGM-CSF [10], aranti-trypsin [12, 29, 38, 39] and human lysozyme [30]. 

The use of hairy roots for the production of biopharmaceuticals has been studied extensively and has been discussed in Chapter 1 of this book. To date, over 116 different plant species have been induced to produce hairy roots in culture (Guillon, 2006). Originally, an expression system was developed for protein production based on the natural secretion from roots of intact plants. In order to take up nutrients from the soil, interact with other soil organisms, and defend themselves against numerous pathogens, plant roots have developed sophisticated mechanisms based upon... 

The production of pharmaceutical proteins using hairy roots and rhizosecretion technology represents a safe and viable alternative to the use of whole plants for molecular pharming. As an example of the efficiency of this system, Medina-Bolivar and Cramer (2004) expressed the reporter protein GFP in tobacco hairy root cultures using a plastic sleeve bioreactor with a 5 L volume. Yields of 500 pg GFP/L after 21 days of incubation or 20% of total secreted protein were produced using this expression system, suggesting that rhizosecretion offers a promising production system for the production of biopharmaceuticals. 

The cell lines most commonly employed for production of biopharmaceuticals include CHO-K1, BHK-21, and Vero cells, besides various antibody-secreting hybridomas. Other cell lines, such as NSO, HEK-293 and PER.C6, have also been employed for recombinant protein production. 

Cells by themselves or by secreting pharmacologically active substances may have effects on the CNS, cardiac, respiratory, renal, or GI systems. Safety pharmacology should therefore be considered on a case-by-case basis depending on the specific characteristics of the cell-based product [52], In general, specific assessments are made as part of the toxicology assessments rather than as stand-alone studies consistent with the assessments made with protein-based biopharmaceuticals [50]. The fundamental physiological differences (e.g., total blood volume,pulmonary capillary surface area, and volume) should... 

Any mammahan ceU line has the basic machinery to express and secrete recombinant protein, and huge numbers of ceU fines with suitable growth properties are available from various tissues and species. The smaU number of cell fines industrially used for manufacturing is, therefore, surprising. Two hamster cell fines, the Chinese hamster ovary cell fine (CHO) and the baby hamster kidney cell fine (BHK), and two geneticaUy related mouse cell fines, the myeloma NSO derived from BALB/c mice, and the hybridoma SP2-0, a fusion of the myeloma with B cells from the same mouse strain, supply most of the mammalian ceU-based biopharmaceuticals, whether marketed or still under development Once commonly accepted as producers, a large body of information about... 

Physcomitrella is a well-established plant system that, since the 1960s, has been cultivated under axenic conditions in many laboratories. It can be cultivated in liquid cultures, and such photobioreactors are scaleable. Transgenic moss strains show high genetic stability. Different biopharmaceuticals, including human growth factor, antibodies and non-glycosylated proteins such as HSA were successfully expressed and secreted into the medium. 

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