Branched Amphiphilic Peptide Capsules (BAPCs): A promising platform for mRNA therapeutics delivery.

Abstract

mRNA therapeutics represent an emerging and powerful strategy for the treatment and prevention of infectious and genetic diseases. However, mRNA molecules are large anionic polymer that necessitate a delivery vector to provide protection from ribonucleases and enhance cellular uptake and delivery. Nanoparticles are recognized for their ability to enhance mRNA stability, improve protection, and facilitate cellular delivery by integrating mRNA into nanocomplexes via electrostatic condensation, encapsulation or surface adsorption. Moreover, tailoring nanoparticle characteristics, including size, shape, and surface chemistry, can significantly influence pharmacokinetic properties such as absorption, distribution, metabolism, and excretion (ADME). Our research team have developed a peptide-based nanoparticles known as Branched Amphiphilic Peptide Capsules (BAPCs). These peptide capsules feature a cationic head group tethered to branched hydrophobic segments, closely resembling the architectural configuration of cell membrane bilayer containing phosphoglycerides. The cationic surface of BAPCs provides a platform to associate nucleic acids through electrostatic condensation. Previous investigations have demonstrated successful surface adsorption and delivery of a DNA vaccine encoding the HPV-16 oncoprotein using BAPCs in a TC-1 tumor mouse model. Mice immunized with BAPCDNA complexes exhibited robust anti-tumor immune responses, resulting in tumor regression and improved survival rates. The primary focus of this dissertation research is to assess the safety and efficacy of BAPCs in delivering mRNA using both in vitro and in vivo models. Initially, I conducted the biophysical characterization of BAPC-mRNA complexes and investigated the mRNA condensation capacity of BAPCs, along with exploring the mechanisms governing mRNA release from their surface. 3 Subsequently, I evaluated the efficacy and toxicity of BAPC-mRNA complexes in in vitro models, determining the optimized BAPC-mRNA formulation for in vivo studies. Additionally, we investigated the in vivo biodistribution of BAPCs in a murine model, assessing how mRNA adsorption on BAPCs surface impacts their biodistribution and organ accumulation. Finally, we conducted a comprehensive assessment of BAPCs safety and mRNA delivery efficacy in vivo. To evaluate the in vivo mRNA delivery efficacy of BAPCs, we employed two mRNA reporters, namely luciferase and ovalbumin. Luciferase mRNA reporters allowed for direct visualization and measurement of mRNA expression upon intramuscular delivery in mice using fluorescence reflectance imaging technique. This study also shed light on the biodistribution of BAPC-mRNA complexes. On the other hand, ovalbumin mRNA reporter served as an antigen precursor to evaluate BAPCs' ability to deliver mRNA and stimulate ovalbumin-specific humoral and adaptive immune responses, with comparisons made to a commercial lipid nanoparticle formulation. This study provided invaluable insights into the potential of BAPCs as a delivery platform for mRNA vaccines.