Supermeres as a novel mRNA delivery platform with favorable renal biodistribution

초록

Introduction Lipid nanoparticles (LNPs) dominate mRNA delivery but face critical limitations: >90% hepatic accumulation, <2% endosomal escape, and anti-PEG antibody formation upon repeated dosing. Here we identify supermeres—non-membranous natural nanoparticles of ~25 nm—as an alternative platform enabling efficient extrahepatic mRNA delivery. We isolated supermeres from HEK293FT conditioned media by sequential ultracentrifugation (367,000 g, 16 h) following removal of large EVs, small EVs, and exomeres. mRNA cargo was loaded via donor cell engineering. We quantified delivery efficiency by RT-qPCR and immunoblotting, confirmed particle identity by marker profiling (TGF-β1, ENO1, CD81), and assessed in vivo biodistribution using Cy5.5-labeled supermeres and IVIS imaging following intravenous administration. Results Quantitative analysis revealed that while supermeres carry significantly lower initial cargo— containing approximately 80-fold fewer eGFP mRNA copies per μg than small EVs—they exhibited a 20-fold increase in mRNA delivery efficiency when normalized to equivalent mRNA input. These findings indicate that supermeres support more efficient cellular internalization and/or endosomal processing than small EVs. In vivo, Cy5.5-labeled supermeres showed minimal liver and spleen accumulation with preferential accumulation in the kidney. Consistent with this biodistribution, eGFP mRNA delivered by supermeres produced stronger functional expression in renal tissue than LNP-delivered mRNA, demonstrating the potential of supermeres for efficient extrahepatic genetic cargo delivery. Conclusion Supermeres overcome key LNP limitations by combining high delivery efficiency with favorable renal biodistribution. These findings position supermeres as a natural platform for next-generation mRNA therapeutics targeting kidney and other extrahepatic organs.