Researchers develop oral delivery of siRNA

We have reported many times on both the promise and the problems associated small interfering RNA (siRNA). They can "silence" genes that cause specific diseases. That’s the promise. The problem? Getting the tiny strands exactly where they need to go without doing unintended harm. The many possible solutions to delivering siRNA has been the subject of much of Fierce Drug Delivery's reporting.

Researchers at the Georgia Institute of Technology and Emory University have come up with an siRNA delivery method that is so simple it could come under one of those why didn’t I think of that?" categories. Their siRNA drug-delivery solution? Swallow them.

Turns out, "delivering" siRNA directly into the stomach could potentially treat inflammatory bowel diseases. What has to happen first, though, is there needs to be some kind of protective covering over the siRNA strands that not only protect the digestive system from harm but also contain just the right chemistry to deliver siRNA to the source of the trouble—inflamed intestines.

The researchers developed a new polymer, which they call thioketal nanoparticles. They're about 600 nanometers in diameter and, in experiments on mice, the nanoparticles traveled directly to the mouse colons, where they remained stable in areas that were not inflamed, but delivered its payload of siRNA to the bad neighborhoods of the colon.

But is it safe? Probably, says Georgia Tech Associate Professor Niren Murthy, since it is based on material already approved by the FDA. "Polymer toxicity is something we'll have to investigate further, but during this study we discovered that thioketal nanoparticles loaded with siRNA have a cell toxicity profile similar to nanoparticles formulated from the FDA-approved material poly(lactic-co-glycolic acid) (PLGA)," Murthy said.

- check out the press release (with handy illustrations and pictures of the gastrointestinal tract)