Muco-Penetrating Lipid Nanoparticles Having a Liquid Core for Enhanced Intranasal mRNA Delivery

Area of Science:

• Nanotechnology and Vaccine Delivery
• Mucosal Immunology
• Respiratory Virus Research

Background:

• Intranasal mRNA vaccines can induce mucosal immunity against airborne viruses (e.g., SARS-CoV-2), preventing infection and transmission.
• A key challenge is overcoming the mucus barrier in the nasal cavity for effective mRNA vaccine delivery.
• Existing mRNA-lipid nanoparticles (ALC-LNP) face limitations in penetrating nasal mucus.

Purpose of the Study:

• To design novel ionizable lipid-incorporated liquid lipid nanoparticles (iLLNs) for effective intranasal mRNA delivery.
• To optimize iLLN properties for enhanced mucus penetration and mucosal immune response.
• To evaluate the efficacy of iLLN-based mRNA vaccines in a preclinical mouse model.

Main Methods:

• Development of iLLNs with tunable pKa by adjusting ionizable and cationic lipid ratios for nasal mucosal pH compatibility (5.5-6.5).
• Formulation of iLLN-mRNA complexes designed for muco-inertness and PEGylation.
• In vivo assessment of reporter gene expression and SARS-CoV-2 specific immune responses (IgA, IgG) in mice following intranasal administration, compared to ALC-LNP.

Main Results:

• The lead iLLN candidate (iLLN-2/mRNA) demonstrated approximately 60-fold greater reporter gene expression in the nasal cavity compared to benchmark ALC-LNP.
• Prime-boost intranasal immunization with iLLN-2/mRNA elicited significantly higher SARS-CoV-2 spike-specific mucosal IgA and IgG responses than ALC-LNP.
• The iLLN formulation did not induce noticeable inflammatory reactions in the nasal mucosa.

Conclusions:

• iLLNs effectively overcome the nasal mucus barrier, enabling superior mRNA delivery and gene expression.
• iLLN-based intranasal mRNA vaccination elicits robust and specific mucosal immunity without significant inflammation.
• These findings provide a promising strategy for developing effective nasally deliverable mRNA vaccines for prophylactic applications against respiratory pathogens.