Safflower-Derived Cationic Lipid Nanoparticles: Potential Impact on the Delivery of SARS-CoV-2 MRNA Transcripts

Abstract

The COVID-19 pandemic has significantly highlighted the successful application of lipid nanoparticles (LNPs) as an advanced platform for mRNA vaccine delivery. Ionizable lipid is the main component for complexing the mRNA in LNP formulation and in vivo delivery. In the first step of this study, we used the native safflower oil seed to prepare dilinoleyl alcohol. Then the cationic lipid DLin-MC3-DMA (MC3) was synthesized by mixing the alcohol with dimethylamino butyric acid. Safflower-derived MC3 was applied to formulate an LNP vector with standard composition. The efficiency of the synthetic cationic lipid was evaluated for delivering an mRNA-based vaccine encoding the receptor-binding domain (RBD) of SARS-CoV-2. The produced mRNA-LNP vaccine candidate was evaluated in size, morphology, mRNA encapsulation efficiency, apparent pKa, and stability for nucleic acid delivery. Cellular uptake was determined by measuring the percentage of GFP expression, and cytotoxicity was assayed using MTT. The MC3 formation was confirmed by the NMR spectra and used as a cationic lipid in LNP formulation. The obtained LNPs had positively charged and appropriate particle sizes (~80 nm) to confer proper encapsulation efficiency for mRNA delivery and stability. The LNPs were shown to be effective in the transfection of mRNA transcripts into HEK293T cells. A high level (72.34%) of cellular uptake was determined by measuring the percentage of GFP expression. The cytotoxicity assay using MTT showed that both LNP and mRNA-LNP were non-toxic to cells. These data demonstrate the potential of the proposed safflower-derived cationic lipid in the formulation of LNP. The carrier provides a promising platform for the efficient delivery of mRNA in vitro. Further evaluations of its potential for in vivo delivery are needed.

Keywords: Cationic Lipid; Lipid-based Nanoparticles; SARS-CoV-2; Safflower oil; mRNA vaccine.

Figure 1

Flowchart of dilinoleyl alcohol synthesis from linolenic acid

Figure 2

Fatty acid compositions of the safflower oil using GC-MS

Figure 3

FTIR spectra of (a) linoleic acid, (b) dilinoleyl alcohol, and (c) dimethylaminobutyric acid. (d) ¹H NMR spectrum of MC3

Figure 4

GelRed pre-stained gel shows the integrity of RBD mRNA. Lane 1: RNA size marker; lane 2: mRNA post-IVT; lane 3: mRNA post capping; lane 4: mRNA tailing resulted in a poly (A) tail of about 140 bases.

Figure 5

Lipid-based nanoparticle physicochemical characterization: (a) dynamic light scattering data represents hydrodynamic size in the range of 81.72 nm; (b) nanoparticle surface charges in terms of potential analysis shows zeta potential −5.83 mV; (c) TEM image indicates the spherical morphology, (d) TNS assay plot of representative LNPs to determine the apparent pKa.

Figure 6

The transfection efficiency of mRNA-LNP in HEK293T cells by flow cytometry. The transfection levels represented as the mean GFP fluorescent signals from 10,000 cells analyzed (left) treated with mRNA-Lipofectamine 2000 and (right) treated with mRNA-LNP.