title: The road to therapeutic RNA interference (RNAi): Tackling the 800 pound siRNA delivery gorilla.
abstract: If those of us privileged enough to have the opportunity to work towards curing human diseases had the power to design the ideal therapeutic molecule, the question would be what selection criteria would we choose? Arguably, at the top of the list would be four mandatory properties: specificity, potency, tolerability, and universality. So it should come as no surprise the momentum associated with the field of small interfering RNA (siRNA)-induced RNA Interference (RNAi) therapeutics has gained strength, as these molecules have shown exceptional promise in fulfilling all of these requirements. Unfortunately, siRNAs are too large, too charged, and too rigid to passively diffuse across the cellular membrane and thereby require a delivery system to enter cells. Thus, since its conception of working in human cells, siRNA delivery remains The 800 Pound Gorilla in the room. The main complication yet to overcome is engineering delivery systems that are safe and efficient in systemically delivering siRNA molecules to the diseased tissue and across the cellular membrane of target cells. Currently, encapsulating the siRNA in nanoparticle and liposomal systems has risen to become the standard of delivery approaches. While generally speaking these delivery platforms offer significant advancements, our laboratory is committed to generating alternative siRNA delivery technologies that avoid nanoparticle packaging and allow siRNA molecules to be delivered as single, soluble entities. This brief review discusses the first of these technologies, a Peptide Transduction Domain-dsRNA Binding Domain (PTD-DRBD) fusion protein that avidly binds to the siRNA backbone to mask the negative charge and uses the PTD for macromolecular cellular delivery.
authors.affiliation: Department of Cellular & Molecular Medicine, UCSD School of Medicine, University of California at San Diego, CA 92093, USA.
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Meade
authors.forename: Steven F
authors.initials: SF
authors.lastname: Dowdy
mesh_terms: D000818:Animals; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry; D034622:RNA Interference / Q000502:physiology; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D004337:Drug Carriers; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins