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New Peptide-Enclosed Vesicles Have Potential for Targeted Drug Delivery

For the first time, researchers at Kansas State University and Jikei University in Japan have designed and created a bounded vesicle formed entirely of peptides -- molecules made up of amino acids, the building blocks of protein. The vesicle could serve as a new drug delivery system to safely treat cancer and neurodegenerative diseases. The study, led by Dr. John Tomich, professor of biochemistry at Kansas State University, was published on September 18, 2012 in the journal PLoS ONE, and a patent for the discovery is pending. The peptides are a set of self-assembling branched molecules made up of naturally occurring amino acids. The chemical properties of the peptides create a vesicle that Dr. Tomich describes as a bubble: It's made up of a thin membrane and is hollow inside. Created in a water solution, the bubble is filled with water rather than air. The peptides -- or bubbles -- can be made in a solution containing a drug or other molecule that becomes encapsulated as the peptides assemble, yielding a trapped compound, much like a gelatin capsule holds over-the-counter oral remedies. The peptide vesicles could be delivered to appropriate cells in the body to treat diseases and minimize potential side effects. "We see this as a new way to deliver any kind of molecule to cells," Dr. Tomich said. "We know that in certain diseases subpopulations of cells have gone awry, and we'd like to be able to specifically target them instead of attacking every cell, including healthy ones." The finding could improve gene therapy, which has the potential to cure diseases by replacing diseased cells with healthy ones. Gene therapy is being tested in clinical trials, but one of the biggest challenge is how best to deliver the genes. Current methods include cells with a virus being injected into the body, and liposomes -- fatty compounds -- carrying the genes. However, these methods may present some problems. When a virus is used, the body's immune system can attack the virus or cause a tumor. Lipid-based systems may cause inflammation and may not properly bind to cells. The peptides created by Kansas State University researchers and collaborators have advantages over their lipid counterparts. The peptides have improved stability and durability, are easier and quicker to create, and they can be delivered to a specific area in the body. The peptides can be designed to have the ability to target cells, tissues, tumors, or organs, and to encapsulate chemical reagents, antibodies, toxins, and inhibitors, Dr. Tomich said. "We don't even begin to know all of the potential applications for this discovery," he said. "We envision that many products could be packaged and delivered using these peptides." [Press release] [PLoS ONE article]