Expression kinetics and innate immune response after electroporation and lipid nanoparticle mediated delivery of a self-amplifying mRNA in the skin of mice

Abstract

word count: 148 Manuscript word count: 4988 Number of references: 55 Number of figures: 8 Number of tables: 1 2 / 28 Graphical abstract AbstractIn this work we studied the expression kinetics and innate immune response of a self-amplifying mRNA (sa-RNA) after electroporation and lipid nanoparticle (LNP) mediated delivery in the skin of mice. Intradermal electroporation of the sa-RNA resulted in a plateau-shaped expression with the plateau between day 3 and 10. The overall protein expression of sa-RNA was significant higher than that obtained after electroporation of pDNA or non-replication mRNAs. Moreover, intradermal electroporation of sa-RNA induced a short-lived innate immune response that did not affect the expression of the sa-RNA. A complete different expression profile and innate immune response was observed when LNPs were used. The expression peaked 24h after intradermal injection of sa-RNA-LNPs and subsequently showed a sharp drop. This drop can be explained by the strong innate immune response elicited by the sa-RNA-LNPs 4h after injection. Interestingly, sa-RNA-LNPs were able to transfection the draining lymph nodes after intradermal injection.

Improving the Repeatability and Efficacy of Intradermal Electroporated Self-Replicating mRNA

“…An intradermal electroporation of sr-mRNA was considered successful when the luciferase expression generated a radiance above 4 × 10 5 photons/s/cm 2 /steradian (p/s/cm 2 /sr) during at least four consecutive days as observed previously 23 . Supplementation of the sr-mRNA just before injection with 0.33 or 1.0 U RNase inhibitor/μL increased the percentage of successful administrations to, respectively, 67% and 100% (total number of administrations was six; Figures 2B and 2C).…”

“…In more recent studies it has been shown that non-viral carriers can reduce the (biologic) variation and increase the efficacy of mRNA therapeutics 11, 14, 16, 17. However, a drawback of non-viral carriers is that they may cause in vivo toxicity,18, 19, 20, 21 potentiate the inherent innate immunity of synthetic mRNA,22, 23 and make the commercial production and registration of mRNA therapeutics more complicated.…”

Corticosteroids and cellulose purification improve respectively the in vivo translation and vaccination efficacy of self-amplifying mRNAs

“…Synthetic self-amplifying mRNAs are known for their high in vivo translational efficiency [21,22]. However, in vivo administration of sa-mRNAs may induce a strong type I IFN response [5,11,23]. While this can be considered advantageous when the sa-mRNA is used for vaccination purposes [11,24], several studies have demonstrated that triggering type I IFN production can negatively impact the intended adaptive immune response of intramuscularly and intradermally administered mRNA vaccines [9,11,15].…”