CHARACTERIZATION AND OPTIMIZATION OF MRNA ENTRAPPED PEPTIDE NANOPARTICLES FOR TARGETED GENE DELIVERY

The mRNA entrapped nanoparticles have the potential to be used in targeted gene delivery. These nanoparticles are used in treating Cancer and neurological disorders. Purpose (a): Generally, mRNA is considered to be very labile and unstable and has not been significantly used for therapeutic purposes. However, compared to DNA based gene expression, mRNA is safer as it is does not integrate with the host genome, and it does not require nuclear localization. The main aim of this project is to entrap the mRNA inside a targeted nanoparticle to increase its stability and the tissue specificity of the gene delivery. Methods (b): The particles were assembled using heat denatured mRNA and a cationic oligomer or detergent to neutralize the negative charge of the polynucleotide. Subsequently phospholipid and a protein/peptide component are added to form the stable mRNA nanoparticle. In order to minimize the size of the particles, the preparation was carried out with several cationic detergents, including Hexadecyltrimethyl ammonium bromide (HTAB), Tetrabutyl ammonium hydroxide (TBAH), and DOTAP. The peptide/protein components were 10-100µg of either Apolipoprotein A-I, or A-I mimetic peptide Myr-5A/ 5A. The incorporation efficiency of the polynucleotide is determined by separating the unincorporated mRNA using OligodT beads and lysing the particles using Trizol reagent to release the entrapped mRNA. Results (c): The yield of the entrapped mRNA analyzed using Ribogreen assay was 17-20%. Based upon the size analysis measurements made using Dynamic Light Scatterer, it was observed that the particles prepared with 5A peptide (10µg) and DOTAP (10µg) resulted in 48% of 268nm particles. Conclusions (d): Further optimization of this formulation may be achieved to produce more homogenous nanoparticles with higher mRNA incorporation efficiency, using DOTAP as the neutralizer and 5A as the peptide.