Nanosized Multifunctional Polyplexes for Receptor-Mediated SiRNA Delivery
journal contributionposted on 2012-06-26, 00:00 authored by Christian Dohmen, Daniel Edinger, Thomas Fröhlich, Laura Schreiner, Ulrich Lächelt, Christina Troiber, Joachim Rädler, Philipp Hadwiger, Hans-Peter Vornlocher, Ernst Wagner
Although our understanding of RNAi and our knowledge on designing and synthesizing active and safe siRNAs significantly increased during the past decade, targeted delivery remains the major limitation in the development of siRNA therapeutics. On one hand, practical considerations dictate robust chemistry reproducibly providing precise carrier molecules. On the other hand, the multistep delivery process requires dynamic multifunctional carriers of substantial complexity. We present a monodisperse and multifunctional carrier system, synthesized by solid phase supported chemistry, for siRNA delivery in vitro and in vivo. The sequence-defined assembly includes a precise cationic (oligoethanamino)amide core, terminated at the ends by two cysteines for bioreversible polyplex stabilization, at a defined central position attached to a monodisperse polyethylene glycol chain coupled to a terminal folic acid as cell targeting ligand. Complexation with an endosomolytic influenza peptide-siRNA conjugate results in nanosized functional polyplexes of 6 nm hydrodynamic diameter. The necessity of each functional substructure of the carrier system for a specific and efficient gene silencing was confirmed. The nanosized polyplexes showed stability in vivo, receptor-specific cell targeting, and silencing of the EG5 gene in receptor-positive tumors. The nanosized appearance of these particles can be precisely controlled by the oligomer design (from 5.8 to 8.8 nm diameter). A complete surface charge shielding together with the high stability result in good tolerability in vivo and the absence of accumulation in nontargeted tissues such as liver, lung, or spleen. Due to their small size, siRNA polyplexes are efficiently cleared by the kidney.
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stability resultsiRNA therapeutics8.8 nm diameternanosized polyplexessurface charge shieldingoligomer designcarrier systemmultifunctional carrier systembioreversible polyplex stabilizationcarrier moleculessiRNA deliverypolyethylene glycol chainNanosized Multifunctional PolyplexesEG 5 gene6 nm hydrodynamic diametersiRNA polyplexesterminal folic acidnontargeted tissuesvivonanosized appearancemultistep delivery processmultifunctional carriers