Science of Gene Therapy Research

Watch a Demonstration Using a 3-D Vector Model

Watch and learn how gene therapy research for hemophilia is exploring whether a vector can be used to deliver a new functional gene to the cell that needs it.

Read full video transcript

For more than 50 years, scientists have been investigating and evolving gene therapy, an approach that aims to address a genetic disease, such as hemophilia, at its source – the gene.

Genetic diseases can be caused by gene mutations – meaning the body does not have the instructions it needs to create the right proteins. Research is exploring whether a new, functional gene can be delivered into a cell to provide instructions to make a desired protein, such as factor VIII or IX in the case of hemophilia.

Together, let’s explore the science behind this investigational approach with our 3D vector model. In gene therapy research, we need a way to get the functional gene into the body. A transporter, called a vector, is used.

Vectors are made from modified viruses. You may associate viruses with things that make you sick, but the most commonly used virus for hemophilia gene therapy research—the adeno-associated virus, or AAV—was chosen because it is not known to cause human disease.

A virus is transformed into a vector by removing the viral genetic information.

Now, the modified viral-based shell can serve as a delivery vehicle.

In a laboratory, the new functional gene is created. It contains the instructions for the cell to make a necessary protein such as factor VIII or IX.

Once created, the new functional gene is placed inside the shell. Together, they become a vector.

In hemophilia gene therapy research, the vector is delivered to the body by IV infusion into the blood. The goal is to deliver the new, functional gene to the liver cells called hepatocytes.

Each viral vector has its own attraction, or tropism, to a certain cell type. In hemophilia, for example, AAV is attracted to the livers cells. Once the vector reaches the liver the new functional gene can enter a cell’s nucleus or command center, where it sits next to the existing DNA.

If transferred successfully, the new gene instructs the liver cells to make the necessary protein. In the case of hemophilia, the gene enables the production of clotting proteins.

Safety and efficacy have not been established. Studies of investigational gene therapy are ongoing and participants continue to be followed.

To learn more about gene therapy research for hemophilia, visit or talk with your healthcare team.