(W1130-04-19) A Novel Solid the Lipid Nanoparticles Formulation with Anti-inflammatory Properties for RNA Delivery

Purpose: Pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α) are highly elevated in many chronic inflammation-related diseases such as arthritis. Solid lipid nanoparticles (SLNs) have been used to deliver TNF-α siRNAs to treat arthritis in mice. However, most siRNA-incorporated SLNs are associated with an acute inflammatory response that may hinder the development of safe and effective treatments for chronic diseases.  This study aims to develop a safe and effective TNF-α siRNA-incorporated SLNs nanoparticles for the treatment of inflammation in mice.

Methods: A newly formulated solid lipid nanoparticles loaded with TNF-α siRNA (KAIMRC-GT5-TNF-α siRNA- SLNs) were made from a composition of natural and chemically modified lipids. Natural phospholipids extraction and purity was confirmed using Corona-HPLC detector. Other SLNs formulations with different ratios of natural to chemically modified lipids were made as controls. The KAIMRC-GT5-TNF-α siRNA- SLNs were characterized in terms of particle size, zeta potential, stability, and siRNA release. Fluorescently labeled siRNAs were used to determine the encapsulation efficiency and the siRNA release. A macrophage mouse cell line was used to evaluate nanoparticles’ performance in vitro. The safety and efficacy of KAIMRC-GT5-TNF-α siRNA- SLNs were assessed in a CAIA mouse model.

Results: KAIMRC-GT5-TNF-α siRNA- SLNs were 100 ± 8 nm in diameter, with a zeta potential of -42 ± 4 mV and a siRNA entrapment efficiency of about 80%. The incubation of the KAIMRC-GT5-TNF-α siRNA at pH 6.8 and 4.5 facilitated the significantly higher release of siRNAs when compared to pH 7.4 and control SLNs at lower pH. The KAIMRC-GT5-TNF-α siRNA- SLNs showed higher binding/uptake by cells in vitro than controls. The PEGylated nanoparticles showed good stability in PBS solution for 30 days and no significant change in size after 24 h in 10% FBS. In vivo, CAIA mice i.v. injected with the KAIMRC-GT5-TNF-α siRNA- SLNs showed a significant reduction in inflammation compared to untreated CAIA mice. More importantly, mice treated with the KAIMRC-GT5-TNF-α siRNA- SLNs showed significant recovery in body weight compared to controls.

Conclusion: We prepared and characterized a novel KAIMRC-GT5-TNF-α siRNA- SLNs formulation that has favorable in vitro and in vivo characteristics for the delivery of RNA-based therapies. The KAIMRC-GT5-TNF-α siRNA- SLNs showed higher efficacy and better tolerability in mice with arthritis.

Acknowledgments: This work was supported by King Abdullah International Medical Research Center (KAIMRC), research contract/grant number RCR798 (RC18/272/R).

Graphic 1 shows the in vitro release of siRNA from different lipid nanoparticle formulations at lower pH environment (pH 6.8 PBS). Data are presented as mean ± S.D. (n = 3).



Graphic 2 shows the stability of PEGylated nanoparticles in a simulated biological medium (10% fetal bovine serum in pH 7.4 PBS, 10 mM). Data are presented as mean ± S.E.M (n = 3).