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January 7th, 2008

Integrated gene delivery vectors—Evolution and prospects

Abstract:
Such safety issues combined with the lack of scalability of viral vectors as vehicles for gene delivery prompted the development of non-viral vectors as gene delivery vehicles. The simplest non-vectors include cationic-polymer-DNA complexes, also known as polyplexes; can be used to deliver DNA into cells. Polyplexes are positively charged complexes of cationic polymers with anionic DNA. Use of cationic materials help condense the negatively charged DNA and reduce its susceptibility to nucleases. In addition, positive charges aid to bind the complex to the negatively charged cell surface and improve the chances of internalisation. Similarly, cationic lipids may be used and the complexes so formed are called lipoplexes. With the advent of nanoscience, the DNA may be complexed with nanoparticles made up of cationic polymers like chitosan or polyethylene imine or cationic lipids like lipofectin. Due to their small size, nanoparticles are deemed to be more efficacious than the simple complexes. Cationic liposomes, owing to their typical bi-layer structure, have also improved the gene delivery efficacy. Liposomes remain one of the most worked upon vehicles from DNA delivery. Many cationic materials are known to cause inflammatory responses and efficacy remains moderate. In spite of these drawbacks, the major achievement of this generation of gene delivery vehicles was of increasing the possible size of the gene they could transfer. While, the highest possible gene size that can be delivered by a virus is eight kda, that with a non-viral vector is at least 50 kda.

Source:
expresspharmaonline.com

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