Targeting in Gene Therapy
One challenge in the development of the gene therapy approach using viral vectors is the specific targeting of the vector to a tissue inside the body, since an untargeted vector can potentially lead to serious side-effects.
One possibility is the engineering of the viral surface proteins so that they specifically bind to cell receptors that are only expressed in the tissue to be targeted. This approach is also called pseudo-typing.
In addition, some viral vectors are known to naturally infect specific tissues, such as adeno-associated virus (AAV) 2 that presents natural tropism towards skeletal muscles, neurons, vascular smooth muscles and liver cells.
Finally, the gene therapy drug can be injected or given intravenously to ensure that a specific tissue in the body is targeted.
Another layer of specificity can further be achieved by expressing the therapeutic gene from a tissue specific promoter.
Figure 1: In the case of gene therapy treatment of heart failure, the therapeutic gene is directly targeted to the heart, for example by intracoronary infusion.