Gene therapy destroys brain cancer in new study

Posted Jul 14, 2015 by Tim Sandle
Technologists have developed a nanoparticle transport system for gene delivery. The system can wipe out brain gliomas, which cause a deadly form of cancer.
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Eric Piermont, AFP/File
With the system, nanoparticles are packed with genes. The genes related to a specific enzyme that converts a pro-drug termed ganciclovir into a chemical that can wipe out glioma cells. Glioma is a tumor that begins in the spine or in the brain (the brain is the most common site.) The risk associated with this type of cancer is high, with a survival rate of less than 10 percent. The exact cause is unknown, although there is a probable genetic connection.
Therapies for giloma are based on delivering specific genes, depending upon the type of tumor and its location in the brain. The main delivery system involves using viruses. However, this mechanism can be unreliable. This type of process is called gene therapy. Most types of gene therapy use DNA to encode a therapeutic gene that, when introduced into the body via a vector, aims to replace the mutated gene causing the cancer.
In place of viruses, the new technology uses biodegradable nanoparticles. The objective is to use something more accurate and less harmful. By being biodegradable, the particles breakdown into harmless compoments, which are then removed from the body.
In new studies, researchers have used an encoding a gene known as HSVtk. This gene uses an enzyme that transforms the compound ganciclovir into a compound that is toxic to brain cancer cells. For the drug delivery system, a polymer called PBAE 447 was found to be the optimal one for the basis of the nanoparticles.
The studies to date relate to experiments conducted using rats, where the rats were developed with brain cancer. In the studies, the life of the rats was extended. The nanoparticles entered the rats through infusion, via an injection into the site of the tumor. Over eight days a measurable reduction of the tumor was seen.
The next phase is to use the non-viral nanomedicine method on other animals, with a view to conducting trials on humans at a later stage.
The study was carried out at the institution NIBIB (National Institute of Biomedical Imaging and Bioengineering). The research has been reported to the journal ACS Nano. The research is titled “Polymeric nanoparticles for nonviral gene therapy extend brain tumor survival in vivo.”