Inhibition of the Inflammatory Pathway Enhances Both the in Vitro and in Vivo Transfection Activity of Exogenous in Vitro-Transcribed mRNAs Delivered by Lipid Nanoparticles.

While the use of in vitro-transcribed mRNA (IVT-mRNA) in therapeutics is a rapidly expanding area, the transfection of the exogenous IVT-mRNA is accompanied by a risk of immune activation. This immunological defense mechanism suppresses cellular translation process and can reduce transfection efficiency to a considerable extent. In the present study, we investigated the in vitro effects of Integrated Stress Response Inhibitor (ISRIB), and dexamethasone, a steroidal anti-inflammatory drug, on the transfection activity of a lipid nanoparticle (LNP) that was composed of ionizable lipids and IVT-mRNA. In the case of transfection to mouse embryonic fibroblast (MEF) cells, ISRIB mainly enhanced the transfection activity at an early stage of transfection (0-6 h). In contrast, dexamethasone caused an increase in transfection activity at intermediate-late stages of transfection (4-48 h). We also investigated the in vivo effects of dexamethasone using an LNP on that the IVT-mRNA and lipid-conjugated dexamethasone (Dex-Pal) were co-loaded. The intravenous administration of the LNP successfully enhanced the protein expression in a mouse liver by up to 6.6-fold. Collectively, the co-delivery of an anti-inflammatory drug is a promising approach for enhancing transfection efficiency of IVT-mRNA.

The delivery of mRNA to colon inflammatory lesions by lipid-nano-particles containing environmentally-sensitive lipid-like materials with oleic acid scaffolds.

An mRNA gene therapy represents a potentially promising therapeutic for curing inflammatory diseases. The transient nature of the gene expression of mRNA would be expected to be beneficial for avoiding undesired side effects. Since the mRNA is a vulnerable molecule, a development of a carrier that can deliver the mRNA to the cytoplasm has a high priority. We report herein on the development of a system for delivering mRNA to the inflammatory lesion in a dextran sulfate sodium (DSS)-induced colitis model. We modulated molecular structures of an ionizable lipid, an SS-cleavable and pH-activated lipid-like material (ssPalm). Among the fatty acids investigated, oleic acid scaffolds (ssPalmO) appeared to be more biocompatible than either myristic acid or linoleic acid scaffolds with the colitis model. The structural modification of the hydrophilic head groups from linear tertiary amines to piperazine rings (ssPalmO-Paz4-C2) resulted in a more than 10-fold higher increasing in the transgene activity in inflammatory colon. The most notable observation is that the transgene activity in the inflammatory colon is significantly higher than that in liver, the major clearance organ of lipid nanoparticles. Collectively, the ssPalmO-Paz4-C2 represents a promising material for the delivery of an mRNA to inflammatory lesions.