At the University of Texas, a new gene therapy system has been developed using methods rooted in synthetic biology. Bioengineers at the University, which is based in Dallas, have found a way to introduce genes into cells on a temporary basis.
This new gene therapy technique could have significant implications for the way certain diseases are treated. A study outlining the method was published in the journal Nucleic Acids Research at the end of last month.
According to the study’s lead author Richard Taplin Moore, the new technique offers some key advantages over other methods of gene therapy that the scientific world is looking into. In particular, the fact that genes only remain in the cells temporarily is a huge step forward. “One reason gene therapies are so difficult to get approved,” he explains, is the fact that they are normally irreversible. Genes introduced into the patient’s cells for therapeutic reasons can persist for a very long time and potentially for the rest of their life, and this creates a lot of potential for complications in the long term.
“Our goal,” Moore said, “was to create a delivery system for therapeutic genes that would self-destruct, giving us more control over the delivered DNA by limiting the time it resides in cells.”
The new synthetic biology technique pioneered by the Texas team, however, is designed so that the genes will only remain present while they are still beneficial. Once the genetic code has been read and acted upon, the gene breaks down. In a number of experiments designed to act as “proof of concept,” a gene for the production of a fluorescent red protein was introduced to human kidney cells. The gene was delivered successfully, and once the required amount of protein had been produced it did indeed “self-destruct.”
It is hoped that this technique may one day enable genes that produce drugs or proteins with a medical benefit may be introduced to those struggling with health conditions. However, the experiments conducted so far have used isolated cells, so naturally a lot of further research into the application of this process to living organisms is needed.
The vector – a delivery mechanism that carries genes into cells – for the new technique was created by using synthetic biology to combine DNA from a number of sources. It contains genes from a virus, certain bacteria, a sea anemone and a cow. The self-destruct mechanism comes from the bacterial genes. These genes are for the production of the protein Cas9, which can cause DNA to break apart. In its original bacterial setting, Cas9 is a defence against other organisms. In its new home, it causes the introduced genes to break apart once their job is done.
The project was referred to as “Mission Impossible” during its early stages. This was a reference not only to the difficulty of the project, but to the TV series of the same name where messages would famously self-destruct after they had been read.