# Functional siRNA Delivery via Jet Nebulization: Proof-of-Concept IL-1ß Silencing in Macrophage-like THP-1 Cells

## TL;DR

This study shows that siRNA can be effectively delivered via nebulization to macrophage-like cells, achieving gene silencing without significant loss of activity.

## Contribution

The study demonstrates functional siRNA delivery via jet nebulization in macrophage-like cells, establishing a practical in vitro platform for RNAi research.

## Key findings

- siRNA-lipoplexes retain gene-silencing activity after aerosolization using a jet nebulizer.
- Three IL-1β-targeting siRNAs showed potent silencing with low cytotoxicity in THP-1-derived macrophage-like cells.
- Formulation parameters significantly influence delivery efficiency of nebulized siRNA.

## Abstract

The efficient delivery of small interfering RNAs (siRNAs) to immune and respiratory cells represents a key methodological challenge in developing inhaled RNA interference (RNAi) approaches. A central question is whether siRNA functionality is preserved following aerosolization, as the mechanical stress of nebulization may compromise siRNA integrity and silencing activity. Here, we report a proof-of-concept study using THP-1-derived macrophage-like cells as a tractable in vitro model to characterize jet nebulization for siRNA delivery. Three siRNA candidates targeting interleukin-1 beta (IL-1β) were computationally designed and validated for potent silencing activity and low cytotoxicity. Using a commercially available, off-the-shelf jet nebulizer combined with Lipofectamine RNAiMAX, we demonstrate that siRNA-lipoplexes retain their gene-silencing activity after aerosolization, achieving robust IL-1β knockdown. The delivery efficiency was influenced by siRNA-lipoplex complexation, highlighting the importance of formulation parameters. These findings establish a practical and accessible in vitro platform for evaluating nebulized siRNA functionality, providing a foundation for future studies in more complex and physiologically relevant airway models.