Contact: to feature here

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Issues in the production of Recombinant proteins in Plants
The advance in the field of recombinant DNA technology and the techniques of plant transformation have helped in the creation of novel platforms for the production of proteins on the whole plants growing in soil or plant suspension cells that are grown in a bioreactor with fully defined synthetic media. Studies related to the use of plants as heterologous expression systems for the expression of recombinant proteins, both native as well as modified therapeutic ones from humans has gained importance in the past two decades with successful experiments related to the plant-based production of pharmaceutical proteins.

The scientists Barta et al. have established the ability of plants to express human genes. They have illustrated the expression of transcripts of human growth hormone fusion gene in the callus tissue of sunflower and undifferentiated tobacco, although there was no detection of any protein formation. Two potential therapeutic proteins have been successfully expressed in plant expression systems: human serum albumin that was expressed successfully in the potato and tobacco leaves and suspension cells and monoclonal antibody expressed in the leaves of tobacco. This process of using the plant-based systems for use as platforms for the effective production of molecules with industrial and pharmacological significance, is termed as ‘molecular farming’ (MF) with the pharmaceutically significant products obtained from them being termed as plant-derived pharmaceuticals (PDPs). A number of PDPs are being developed and commercialized that include antigens, blood substitutes, different enzymes, cytokines, antibodies and their fragments and many other important proteins.

The plant expression systems offer a number of advantages over other expression system platforms for the production of recombinant proteins such as being inexpensive, scaled highly as well as unsupportive of the growth of human pathogens. Due to the advantages offered, replacing the mammalian cell lines with plants for the expression and production of recombinant proteins was considered, though it had some technical drawbacks. The high investment involved with fermentation infrastructure, low grade performance of plants when compared to mammalian cell lines and the lack of regulation systems in plants for the production of biopharmaceutical products resulted in the lack of industrial interest.

Latest research has helped in overcoming the technical hurdles in the utility of plant expression systems.

a) Improvement of the intrinsic yields could be done by maximizing transcription by optimal expression construct designing, stability of mRNAs for translation, increasing the copy number of transgene and introduction of these transgenes within the germplasm. Reverse transition cycling is one of the methods employed for increasing yield and for convenient extraction. This process has been employed in some oil crops as well as seed storage proteins.

b) The downstream processing (DSP) of the yielded protein is very essential that requires the isolation of the expressed protein and involves the removal of fibers, by-products of metabolism as well as oil, based on the crops involved as in case of nicotine from tobacco leaves, etc.

c) One of the regulatory aspects of MF is the presence of plant glycans that may be necessary for the biological activity, stability, targeting, PK (Pharmacokinetic) as well as immunogenic properties of the therapeutic proteins that are glycoprotein. in nature.
However, the differences between plant and human glycans and the effect of the plant glycans on the protein structure, activity, etc have resulted in initiating research to abolish the plant-specific glycosylases by gene knockout and RNA interference as seen in tobacco, Arabidopsis, etc.

The absence of commercial pedigree of proteins was one of the hurdles faced by MF solved by the production of non-medical proteins by the plants for the commercial use. E.g. Maize was used as a platform for the production of avidin and β-glucoronidase (GUS) enzymes that have potential use in molecular biology. Both the proteins were similar to the natural ones in every aspect of activity, structure, etc. Although, there has not been much progress in the commercial production of such type of proteins for therapeutic use, it opens up new prospect for future research studies.

The regulatory perspective of the PDPs that involves the replacement of cell banks with seed banks, accounting natural variation in the plant organs by verifying batch to batch consistency, operating and processing techniques for various expression and production systems are some of the guidelines of FDA for the commercialization of plant-derived proteins.

The good manufacturing practice (GMP) strategy of the PDPs from whole plants is essential for the development of plant expression systems that includes

1) the selection of appropriate plants or crops as expression systems,
2) selection of proper cultivation method,
3) Knowledge of relative merits about the stable as well as transient expression systems and the DSP in plant systems compared to the other cell lines like mammalian, yeast, or bacterial.

The use of PDPs in near future can be foreseen in the development of various pharmaceutical products, vaccines, etc by solving the issues and adopting different strategies of GMP.
Like Post Reply

Possibly Related Threads…
Last Post

Users browsing this thread:
1 Guest(s)

Issues in the production of Recombinant proteins in Plants00