Systemic delivery of siRNA by hyaluronan-functionalized calcium phosphate nanoparticles for tumor-targeted therapy

Abstract

In this study, hyaluronan (HA)-functionalized calcium phosphate nanoparticles (CaP-AHA/siRNA NPs) were developed for an injectable and targetable delivery of siRNA, which were prepared by coating the alendronate-hyaluronan graft polymer (AHA) around the surface of calcium phosphate-siRNA co-precipitates. The prepared CaP-AHA/siRNA NPs had a uniform spherical core-shell morphology with an approximate size of 170 nm and zeta potential of -12 mV. The coating of hydrophilic HA improved the physical stability of nanoparticles over one month due to the strong interactions between phosphonate and calcium. In vitro experiments demonstrated that the negatively charged CaP-AHA/siRNA NPs could effectively deliver EGFR-targeted siRNA into A549 cells through CD44-mediated endocytosis and significantly down-regulate the level of EGFR expression. Also, the internalized CaP-AHA/siRNA NPs exhibited a pH-responsive release of siRNA, indicating that the acidification of lysosomes probably facilitated the disassembling of nanoparticles and the resultant ions sharply increased the inner osmotic pressure and thus expedited the release of siRNA from late lysosomes into the cytoplasm. Furthermore, in vivo tumor therapy demonstrated that high accumulation of CaP-AHA/siEGFR NPs in tumor led to a significant tumor growth inhibition with a specific EGFR gene silencing effect after intravenous administration in nude mice xenografted with A549 tumor, along with a negligible body weight loss. These results suggested that the CaP-AHA/siRNA NPs could be an effective and safe systemic siRNA delivery system for a RNAi-based tumor targeted therapy strategy.

Engineering Nanoparticles for Targeted Delivery of Nucleic Acid Therapeutics in Tumor

“…A report said that low-to-moderate elevation of Ca 2+ concentration (0.2–0.4 μM) triggers apoptosis and higher concentrations of Ca 2+ (>1 μM) are associated with necrosis; the normal extracellular Ca 2+ concentration is ∼1.2 mM and the cytosolic concentration is ∼0.1 μM. 112 However, in the application of CaPs, researchers performed one more layer of CaPs covering DNA-coated CaPs, including PEI, 113 liposome, 114 , 115 , 116 , 117 hyaluronan (HA), 118 or PEG-biophosphonates, 119 which can enable the prepared CaP NPs to remain physically stable over a long time and effectively protect siRNAs from enzymatic degradation under physiological conditions, although the elevated Ca 2+ concentration was only a transient event and not toxic to the cells. 120 …”

Advances in Stimulus‐Responsive Polymeric Materials for Systemic Delivery of Nucleic Acids

“…Moreover, comprehensive studies of the nanoparticles confirmed their superior safety both in vitro and in vivo. Qiu and coworkers prepared an alendronate-hyaluronan graft polymer (AHA) as the outer shell to stabilize CaP nanoparticles [37]. The inner core of the nanoparticles was formed by the CaP-siRNA co-precipitate, followed by the strong interaction between the calcium ions and the negatively charged phosphate of AHA.…”

Dual delivery of nucleic acids and PEGylated-bisphosphonates via calcium phosphate nanoparticles

“…The ideal nanosized vehicle should selectively and efficiently deliver a gene to target cells with minimal toxicity. Additional desirable properties are ease of production, long shelf-life, high payload for genetic material and versatility of surface functionalization [4][5][6][7]. The most investigated and successful physicochemical methods for DNA delivery involve its electrostatic complexation to polycations (polyplexes) and/or cationic lipids (lipoplexes) [8].…”