Nanosized multifunctional polyplexes for receptor-mediated siRNA delivery.
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.
Pharmaceutical Biotechnology, Center for NanoScience, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, 81377 Munich, Germany.
Christian
C
Dohmen
Daniel
D
Edinger
Thomas
T
Fröhlich
Laura
L
Schreiner
Ulrich
U
Lächelt
Christina
C
Troiber
Joachim
J
Rädler
Philipp
P
Hadwiger
Hans-Peter
HP
Vornlocher
Ernst
E
Wagner
D000818:Animals; D020868:Gene Silencing; D008422:Materials Testing; D051379:Mice; D053769:Nanocapsules / Q000008:administration & dosage* / Q000737:chemistry; D009374:Neoplasms, Experimental / Q000235:genetics* / Q000628:therapy*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry*; D016896:Treatment Outcome
D053769:Nanocapsules; D034741:RNA, Small Interfering