Nanoparticles extend reach of RNAi drugs to immune cells

Gene-silencing drugs homed in on tissues deep in the bodies of lab animals, specifically inflammatory monocytes and certain immune cells, shining light on new potential applications of RNA-interference drugs. Scientists from Alnylam Pharmaceuticals ($ALNY) worked with researchers in Boston and British Columbia on a pair of new studies that show how new nanoparticles were able to deliver gene-silencing short interfering RNAs to silence the right genes in the right place.

Cambridge, MA-based Alnylam--which has looked far and wide for groups to help the firm overcome delivery challenges--worked with investigators at Massachusetts General Hospital and MIT drug-delivery experts such as Robert Langer on lipid nanoparticles that found their way to inflammatory monocytes in bone marrow and the spleen.

The particles delivered siRNAs that turned off the gene for the CCR2 protein receptor that guides a type of monocyte to sites of inflammation, which damages tissue and worsens certain diseases. By reducing the numbers of these monocytes at inflammation sites in animals, the researchers showed that the RNAi-carrying nanoparticle cut down on muscle damage from a heart attack and boosted survival of transplanted pancreatic cells, among other benefits. The study was published in the journal Nature Biotechnology.

In a separate study, published in Molecular Therapy, Alnylam worked with scientists from the University of British Columbia on lipid carrier particles that targeted antigen-presenting macrophages and dendritic cells. Researchers believe that delivering RNAi drugs to these immune cells could lead to autoimmune disease treatments and cancer immunotherapies.

Naturally, these are not human data that can rescue the wounded RNAi field, which has seen cutbacks from Big Pharma outfits such as Merck ($MRK), Roche and Novartis ($NVS). But these studies do highlight the potential to carry the gene-silencing drugs to cells that are important in a host of major diseases. That's progress.

- here's the release