Pulmonary Delivery of Self-Amplifying RNA: Balancing Inflammation and Durable Transgene Expression

Area of Science:

• Biotechnology
• Immunology
• Pulmonary Medicine

Background:

• Self-amplifying mRNA (saRNA) is a promising platform for vaccines and gene therapy.
• Lipid nanoparticles (LNPs) are commonly used for saRNA delivery.
• Pulmonary delivery of saRNA-LNPs can trigger innate immune responses, potentially causing lung inflammation.

Purpose of the Study:

• To investigate the safety and efficacy of intratracheal saRNA-LNP delivery.
• To optimize saRNA-LNP formulations to mitigate lung inflammation.
• To assess transgene expression and therapeutic protein production in the lungs.

Main Methods:

• Intratracheal administration of saRNA-LNPs in mice.
• Systematic optimization of LNP formulation and saRNA dosage.
• Evaluation of innate immune cell recruitment and cytokine release in lung tissue.
• Assessment of transgene expression levels and duration.
• Detection of SARS-CoV-2 nanobodies in lung tissue.

Main Results:

• Intratracheal saRNA-LNP administration induced lung inflammation, characterized by immune cell infiltration and cytokine release.
• Optimized saRNA-LNP formulations significantly reduced lung inflammation.
• High levels of transgene expression were achieved in mouse lungs, persisting for at least 21 days.
• Intratracheal delivery of optimized saRNA-LNPs encoding SARS-CoV-2 nanobodies led to detectable nanobody levels in the lungs.

Conclusions:

• Pulmonary delivery of saRNA-LNPs can be achieved safely and effectively through formulation optimization.
• Optimized saRNA-LNPs offer a viable strategy for lung-targeted gene therapy and vaccination.
• This approach holds potential for treating pulmonary diseases and delivering therapeutic proteins directly to the lungs.