Cardiomyocyte-targeted siRNA delivery by prostaglandin E2-Fas siRNA polyplexes formulated with reducible poly(amido amine) for preventing cardiomyocyte apoptosis

Abstract

A cardiomyocyte-targeted Fas siRNA delivery system was developed using prostaglandin E 2 (PGE 2 )-modified siRNA polyplexes formed by a reducible poly(amido amine) to inhibit cardiomyocyte apoptosis. PGE 2 , which was used as a specific ligand for cardiomyocyte targeting, was conjugated to the terminal-end of the sense siRNA (PGE 2 -siRNA). The reducible cationic copolymer, synthesized via Michael-type polyaddition of 1,6-diaminohexane and cystamine bisacrylamide (poly(DAH/CBA)), tightly condensed the PGE 2 -siRNA conjugate to form nanosize polyplexes having a diameter of 100-150 nm. The PGE 2 -siRNA/poly(DAH/CBA) polyplexes decomplexed to release PGE 2 -siRNA in a cytosolic reducing environment due to the degradation of the reducible poly(DAH/CBA). The cellular uptake of the PGE 2 -siRNA/poly(DAH/CBA) polyplex was increased in rat cardiomyocytes (H9C2 cells) due to PGE 2 receptor-mediated endocytosis. When H9C2 cells were transfected with siRNA against Fas, a key regulator of ischemia-induced apoptosis, the PGE 2 -Fas siRNA/poly(DAH/CBA) polyplex delivery system led to a significant increase in Fas gene silencing, resulting in inhibition of cardiomyocyte apoptosis. The PGE 2 -Fas siRNA/poly(DAH/ CBA) polyplex did not induce interferon-alpha in peripheral blood mononuclear cells. These results suggest that the PGE 2 -Fas siRNA/poly(DAH/CBA) polyplex formulation may be clinically applicable as a cardiomyocyte-targeted Fas siRNA delivery system to inhibit apoptosis in cardiovascular disease.

Bioreducible polymers for therapeutic gene delivery

“…To overcome these hurdles, delivery of siRNA with polymeric carriers has been proposed as an attractive solution. In our previous studies, we have reported the cardiomyocyte-targeting bioreducible polymer for siRNA delivery to the myocardium [60–63]. …”

Functional polymers of gene delivery for treatment of myocardial infarct

“…A linear SS-PAA, synthesized by copolymerization between 1,6-diaminohexane and cystamine bis-acrylamide (cystamine bisacrylamide-diamino hexane (poly(DAH/CBA)), served as a powerful vector to carry Fas siRNA into rat cardiomyocytes [104]. PGE2 was conjugated to Fas siRNA molecules, and the synthesized PGE2–Fas siRNA contributed to cardiomyocyte targeting via PGE2 receptor-mediated intracellular delivery.…”

Self-Assembled and Nanostructured siRNA Delivery Systems

“…1): (a) formation of compact nano-scale complexes between nucleic acid drug and carrier compounds, (b) choice of a route of administration, (c) systemic circulation, (d) target tissue localization, (e) intracellular transport, (f) escape from endocytic compartments such as endosomes and lysosomes, (g) nuclear transport, and (h) gene expression (6). Unlike plasmid DNA for gene expression, siRNA needs to rapidly escape from the intracellular organelles into the cytoplasm without being localized to the nucleus, where siRNA induces RNAi (7). Although a number of previously developed gene carriers have been used for siRNA, RNAi-based approaches for clinical therapy require more carefully designed delivery systems to achieve the maximum gene silencing effect.…”