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Knockdown of Gene Expression in Macrophages by microRNA Mimic-Containing Poly (Lactic-co-glycolic Acid)
Paul J McKiernan1, Patrick Lynch2,3, Joanne M Ramsey4,5,6,7
1Department of Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland. pmckiernan3@gmail.com.
Abstract:
Background: microRNA (miRNA) regulate target gene expression through translational repression and/or mRNA degradation and are involved in the regulation of inflammation. Macrophages are key inflammatory cells that are important in chronic inflammatory lung diseases such as cystic fibrosis (CF). Macrophage-expressed miRNA represent therapeutic drug targets, yet delivery of nucleic acids to macrophages has proved challenging. Methods: miRNAs were encapsulated in poly (lactic-co-glycolic acid) (PLGA)-based microparticles using double emulsion solvent evaporation and characterised for physicochemical features. Phorbol myristic acetate (PMA)-differentiated U937 macrophages were transfected with empty PLGA microparticles or those encapsulating a premiR-19b-3p or scrambled control miRNA mimic. miRNA internalisation and knockdown of a miR-19b-3p target gene, secretory leucoprotease inhibitor (SLPI), were determined by qRT-PCR. Results: Microparticle formulations were consistently found to be 2⁻3μm and all had a negative ζ potential (-5 mV to -14 mV). Encapsulation efficiency of premiR-19b-3p was 37.6 ± 13.4%. Levels of mature miR-19b-3p were higher in macrophages after delivery of premiR-19b-3p microparticles compared to empty or scrambled control miRNA-containing microparticles. Significant SLPI knockdown was achieved 72 hours post-delivery of premiR-19b-3p microparticles compared to controls. Conclusions: miRNA-encapsulating PLGA microparticles offer a new treatment paradigm for delivery to macrophages that could potentially be administered to CF lungs via inhalation.
Insights
Microparticles effectively deliver microRNA (miRNA) to macrophages, reducing target gene expression. This novel approach shows promise for treating inflammatory lung diseases like cystic fibrosis via inhalation.
Area of Science:
- Biomedical Engineering
- Molecular Biology
- Drug Delivery Systems
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression and inflammation.
- Macrophages play a critical role in chronic inflammatory lung diseases, including cystic fibrosis (CF).
- Targeting macrophage-expressed miRNAs is a therapeutic strategy, but efficient nucleic acid delivery remains a challenge.
Purpose of the Study:
- To develop and characterize poly (lactic-co-glycolic acid) (PLGA)-based microparticles for miRNA delivery to macrophages.
- To evaluate the efficacy of encapsulated miRNA in modulating target gene expression in macrophages.
- To assess the potential of this delivery system for treating CF lung inflammation.
Main Methods:
- miRNAs were encapsulated in PLGA microparticles using a double emulsion solvent evaporation technique.
- Physicochemical properties of microparticles were characterized, including size and zeta potential.
- PMA-differentiated U937 macrophages were transfected with miRNA-loaded microparticles, and miRNA internalisation and target gene (SLPI) knockdown were quantified using qRT-PCR.
Main Results:
- PLGA microparticles demonstrated consistent size (2-3 μm) and negative zeta potential (-5 to -14 mV).
- Encapsulation efficiency for premiR-19b-3p was 37.6 ± 13.4%.
- Delivery of premiR-19b-3p-loaded microparticles resulted in significantly higher mature miRNA levels and substantial knockdown of the target gene SLPI in macrophages within 72 hours.
Conclusions:
- miRNA-encapsulating PLGA microparticles represent a viable strategy for targeted delivery to macrophages.
- This novel delivery system holds potential for therapeutic applications in inflammatory lung diseases.
- Inhalable administration of these microparticles could offer a new treatment paradigm for cystic fibrosis patients.
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