Peptide- and polymer-based delivery of therapeutic RNA

Small interfering RNA (siRNA) and other synthetic RNA molecules are the new hope in the field of therapeutic gene modulation. The successful use of these nucleic acids in medicine requires efficient delivery of the RNA into the right compartment of the target cells, which in most applications is the cytosol. For this purpose the therapeutic RNA can be assembled with polymers and peptides into nanoparticles of virus-like dimensions. Such synthetic virus-like nanosystems have to be dynamic in their characteristics to be most effective at the different steps of extracellular and intracellular delivery. They must protect the siRNA from degradation in the bloodstream and shield against unspecific interactions, they should facilitate specific targeting and uptake into the diseased cell and triggered release into the cytosol. Current strategies to develop targeted dynamic polymer-based carriers for effective delivery of therapeutic RNA are discussed.