Unique Polymer Delivers Genetic Medicine, Allows Tracking

A scientist has developed a new molecule that can travel into cells, deliver genetic payload, and carries a beacon so that scientists can follow its movements in living systems.

"My lab has been trying to find a way to deliver genetic-based drugs into cells," said Dr. Theresa M. Reineke, associate professor of chemistry in the Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, VA, USA) College of Science, and colleagues in her lab at Virginia Tech and at the University of Cincinnati (OH, USA).

Scientists worldwide are using information from the human genome project as an approach to treat disease. Dr. Reineke's focus is cancer and cardiovascular disease. "Traditional drugs are aimed at treating disease at the protein level,” she said. "Genetic drugs--such as those that can alter or control gene expression--aim to treat disease at the genetic level and have the added benefit of being more specific for their medicinal target.” An example would be a genetic message that would arrest tumor growth.

A key problem has been that DNA and RNA drugs -pieces of genetic code that store information and instructions--cannot diffuse through the cell the way traditional small molecule drugs can. "We needed a vehicle to carry them into cells,” said Dr. Reineke. One such vehicle has been an engineered virus. Dr. Reineke's group has been working on a better-designed solution.

The scientists created novel polycations, which is a polymer chain with positive charges, which is not too unusual. DNA itself is a polyanion, a polymer with negative charges. However, the Reineke group's supramolecule has options. It contains chemistry (oligoethyleneamines) that binds and compacts nucleic acids--pieces of the DNA--into nanoparticles. It also incorporates a group of rare-earth elements known as lanthanides. The repackaged DNA is protected from damage as it travels into the cells and the lanthanides allow visualization of the delivery into cells.

"In our experiments, these delivery beacons provide the ability to track DNA delivery into living cells,” said Dr. Reineke. "They provide the potential for tracking genetic therapies within the living body,” she said.

At the nanometer or cellular level, the researchers are able to track the polymers using sensitive microscopes, which capture the nanoparticle luminescence. At the submillimeter or tissue scale, magnetic resonance imaging (MRI) is used to see where the nanoparticles are going. "This ability to track the movement and delivery of a gene-based drug provides an opportunity to understand the mechanism of delivery and monitor efficacy in real time, so that we can develop better materials for delivering genetic therapeutics and ultimately better treatments,” Dr. Reineke said.

The research was published in the September 23, 2009, online edition of the Proceedings of the [U.S.] National Academy of Sciences (PNAS).

Dr. Reineke has just been awarded the U.S. National Institutes of Health (Bethesda, MD, USA) Director's New Innovator Award.

Related Links:
Virginia Polytechnic Institute and State University
University of Cincinnati