The Therapeutic Potential of Gene Therapy

1334 Words6 Pages
A novel therapeutic modality, gene therapy is the transfer of nucleic acids – DNA or RNA – into select somatic (body) cells to correct genetic defects or produce therapeutic proteins. It can be performed ex vivo (“out of the living”) or in vivo (“within the living”). In the ex vivo method, the target cells are removed from the patient, genetically modified, and reintroduced into the patient's body. This approach is efficient but limited to easily accessible cells such as epithelial cells (cells covering internal and external surfaces of the body), muscle cells, blood cells, and stem cells. In the in vivo method, a gene delivery system transfers the genetic material into the target cells within the patient's body. The development of safe…show more content…
Existing gene delivery systems can be broadly classified into two categories: viral and non-viral. The first gene delivery systems were viral. Viruses were the first choice for vectors in early studies of gene therapy because they have evolved to effectively transfer DNA into target cells. To produce viral vectors, the sections of the virus's genome that enable it to replicate are removed and replaced with the therapeutic gene sequence. The result is an attenuated virus capable of efficiently transferring the therapeutic gene sequence but incapable of replicating in vivo. Disadvantages of viral vectors include limited DNA-carrying capacity, restricted cell targeting, and immunogenicity. Non-viral gene delivery systems seem to be a promising alternative. Non-viral vectors consist of naked DNA in the form of plasmids (circular pieces of DNA) or oligonucleotides (short, single-stranded pieces of DNA) and complexed – “packaged” – DNA, typically with cationic (positively charged) lipids or polymers. In general, naked DNA is safer but significantly less efficient than viral vectors. Barriers to efficient non-viral gene delivery include DNA degradation, lack of cell targeting, and limited cell uptake of DNA. However, the complexation of naked DNA facilitates the process since cationic lipids and polymers protect the DNA and facilitate transport. Current research efforts primarily focus on the development of more efficient non-viral gene
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