Nasal Delivery of mRNA Using Thermoresponsive Gellable Aqueous Biphasic Systems.

Messenger ribonucleic acid (mRNA) emerged as a versatile therapeutic for the prevention and treatment of various diseases, being widely used in the "third-generation vaccines." Innovative delivery vehicles, including lipid nanoparticles and liposomes, were developed to preserve mRNA and allow efficient delivery. On the other hand, nasal vaccination has demonstrated to be effective against respiratory infections. Nevertheless, mRNA's vulnerability to enzymatic degradation, low nasal permeability, and rapid clearance are still critical challenges. Liposomal hydrogels enable bioadhesion and localized drug release; however, these may exhibit cytotoxicity due to the required cross-linking agents. To overcome these drawbacks, a gellable aqueous biphasic system (ABS), composed of water, poly(ethylene) glycol, and gelatin is proposed, as a promising approach for mRNA nasal delivery. This approach, using a gellable biopolymer, eliminates the need for chemical cross-linkers. The developed liposomal hydrogels enables localized and safe mRNA release without associated cytotoxicity toward upper airway epithelial cells. Validation through scanning electron and fluorescence microscopies reveal efficient mRNA entrapment, with a prolonged delivery of up to 30 min. Additionally, by entrapping nanoparticles within hydrogels, a significant reduction in toxicity is demonstrated. The formulated liposomal hydrogels demonstrate comparable transfection efficiency to commercial alternatives, showcasing their potential for safe and effective nasal gene delivery.