U-shaped Lipoamino Fatty Acid-Peptide Polyplexes enhance mRNA delivery to lung cells and in vivo

Local pulmonary delivery of mRNA therapeutics offers a non-invasive route for applications like mucosal vaccination or treating lung diseases. However, efficient delivery is severely challenged by major lung-specific barriers, particularly mucus, which limits bioavailability at the target site. Current delivery systems often struggle to overcome these complex biological environments. Developing pH-responsive, amphiphilic carriers capable of navigating these barriers is crucial for advancing inhaled mRNA therapeutics and addressing this critical delivery gap.

Researchers evaluated pH-responsive, amphiphilic xenopeptides, specifically U-shape and bundle topology polyplexes, for mRNA delivery. These were tested in A549 and Calu-3 lung cells under standard submerged and air-liquid interface (ALI) transfection conditions. In vivo, polyplexes were applied via intratracheal administration in BALB/c mice. Optionally, polyplexes were coated with negatively charged hyaluronic acid (HA) or colloidally stabilized with poly(ethylene glycol) (PEG) to assess the impact of surface modification on delivery efficiency.

Hydrophobic modification of the oligoamino acid (OAA) domain significantly boosted the efficiency of U-shape polyplexes. Interestingly, the best-performing formulations varied across transfection conditions. While the bundle topology showed the highest potential in submerged cell culture, U-shaped carriers were more efficient under ALI conditions. Polyplex surface modification with HA or PEG did not strongly alter in vitro transfections. However, hydrophobized U-shape core polyplexes combined with surface modification notably enhanced their efficiency in vivo. The study highlights that the cationizable core and surface properties of mRNA nanoparticles require specific balancing for optimal performance across various lung cell models and in vivo.