Definition

Gene therapy is the use of DNA as a drug to treat disease by delivering therapeutic DNA into a patient’s cells. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace a mutated gene. Other forms involve directly correcting a mutation, or using DNA that encodes a therapeutic protein drug (rather than a natural human gene) to provide treatment (“Gene therapy”, Wikipedia).
Gene therapies can be categorized as somatic gene therapies and germline ones by target cell or virus-vectored or non-virus-vectored by vector.

History

Genetic engineering techniques have invoked people’s interest in DNA modifying for clinical use. Early in 1972, the idea of gene therapy was first put forward.
The first gene therapy case is in US in 1990. Then in the 1990s there are several successful cases, though partly, but the death in a gene therapy clinical trial in 1999
In 2003 a team from UCLA inserted a gene into the brain, which is a great step in brain disease treatment.
In 2007 the first gene therapy operation was performed for a patient with inherited retina disease, yielding positive results.
In 2012, Glybera became the first gene therapy treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.
By now in 2014 gene therapy is still more of an experimental approach than a clinical therapy.

Advantage and drawbacks

The advantages of gene therapies are quite obvious that they can cure treat some most difficult diseases under traditional therapies and previous experiments of gene therapies have shown some promising cases. The discovery of AAV with specific insertion site adds to people’s expectation.
However, there are a number of technological problems in front of gene therapy, including short-lived nature of gene therapy, potential risk with viral vectors and misinsertion for cancer, and weakness in multigene diseases, etc. Even deaths are reported in gene therapy trials. High cost may be another drawback for the current available gene therapy.

About AAV

AAV, adeno-associated virus, is a common small virus affecting human and some other primates. It is famous for lack of pathogenicity and specific integration site in host genome, which bestows it many nominations in gene therapy.
Alipogene tiparvovec is a gene therapy treatment for lipoprotein lipase deficiency (LPLD), which can cause severe pancreatitis. In July 2012, the European Medicines Agency recommended it for approval, making it the first recommendation for a gene therapy treatment in either Europe or the United States. After the endorsement of the European Commission, Glybera (trade name for Alipogene tiparvovec) becomes the first gene therapy treatment approved for clinical use in either Europe or the US.

Connection with our project

In our project we make use of the AAV as the carrier of the insulin gene, as well as other regulatory elements, trying to eventually recover the insulin expression inside patients’ bodies. It is based on the previous successful trials carried out for treating LPLD (lipoprotein lipase deficiency) with Alipogene tiparvovec (an AAV-based gene therapy).