mRNA-Loaded Lipid Nanoparticles Targeting Immune Cells in the Spleen for Use as Cancer Vaccines

Abstract

mRNA delivery has recently gained substantial interest for possible use in vaccines. Recently approved mRNA vaccines are administered intramuscularly where they transfect antigen-presenting cells (APCs) near the site of administration, resulting in an immune response. The spleen contains high numbers of APCs, which are located near B and T lymphocytes. Therefore, transfecting APCs in the spleen would be expected to produce a more efficient immune response, but this is a challenging task due to the different biological barriers. Success requires the development of an efficient system that can transfect different immune cells in the spleen. In this study, we report on the development of mRNA-loaded lipid nanoparticles (LNPs) targeting immune cells in the spleen with the goal of eliciting an efficient immune response against the antigen encoded in the mRNA. The developed system is composed of mRNA loaded in LNPs whose lipid composition was optimized for maximum transfection into spleen cells. Dendritic cells, macrophages and B cells in the spleen were efficiently transfected. The optimized LNPs produced efficient dose-dependent cytotoxic T lymphocyte activities that were significantly higher than that produced after local administration. The optimized LNPs encapsulating tumor-antigen encoding mRNA showed both prophylactic and therapeutic antitumor effects in mice.

Emergence of SARS‐CoV‐2 spike protein at the vaccination site

“…Against the background of experimental data on the uptake and fate of mRNA vaccines, this selectivity is remarkable since Shimosakai et al, for example, showed an uptake of mRNA-loaded LNPs also in B-lymphocytes. 14 Our in vitro experiments showed that spike protein production of lipid-shuttle-based vaccine (Cormirnaty) treated cells can be detected shortly after vaccine exposure of cultured fibroblasts and an interdigitating dendritic sarcoma cell line. Considering that the maximal protein production after intradermal injection of mRNA in mice was reached after 24-48 h and that the estimated half-life time for mRNA-based vaccines is expected to be around 2 days 15 should have been sufficient for spike protein production in all cells that had taken up the spike protein-coding nucleic acids.…”

“…Against the background of experimental data on the uptake and fate of mRNA vaccines, this selectivity is remarkable since Shimosakai et al, for example, showed an uptake of mRNA‐loaded LNPs also in B‐lymphocytes. 14 …”

Lipid- and Polymer-Based Nanocarrier Platforms for Cancer Vaccine Delivery

“…53 An mRNA LNP formulation was designed to target APCs in the spleen by optimizing the lipid composition, specifically the type of helper lipid. 54 Another study explored the role of the sterol component (cholesterol versus βsitosterol) as well as the fusogenic helper lipid in optimizing the transfection efficiency and T cell activation by mRNA LNPs. 55 The search for the optimal lipids for mRNA LNPs has been the subject of many investigations.…”

“…Recently, a lymph node-targeted LNP-based mRNA vaccine was developed, which exhibited robust CD8 + T cell responses and enhanced antitumor immunity in B16F10 melanoma-bearing mice . An mRNA LNP formulation was designed to target APCs in the spleen by optimizing the lipid composition, specifically the type of helper lipid . Another study explored the role of the sterol component (cholesterol versus β-sitosterol) as well as the fusogenic helper lipid in optimizing the transfection efficiency and T cell activation by mRNA LNPs …”

Immunogenicity of lipid nanoparticles and its impact on the efficacy of mRNA vaccines and therapeutics

“…mRNA vaccines have become a promising platform for cancer immunotherapy 99 , 100 . Applying mRNA-LNP as a cancer vaccination requires a robust immune response 80 , 101 . To improve the efficacy of mRNA-LNP vaccines, adjuvants are included.…”