Antisense Oligonucleotide-Loaded Liposomes for Gene Silencing in Bacterial Biofilms

Abstract

The key pathogens found in chronic wound infections include Pseudomonas aeruginosa [P. aeruginosa] and Staphylococcus aureus [S. aureus], which can form biofilms on compromised skin barriers. Once bacteria attach and proliferate in the affected areas, they begin to secrete various virulence factors and other extracellular molecules, such as exopolysaccharides, for their survival and persistence at these sites of infection. These factors are secreted through a complex cell-to-cell communication system termed ‘quorum sensing,’ through which bacterial phenotypes are modulated. These phenotypic changes occur in response to cell density as induced by small diffusible elements termed autoinducer factors capable of regulating gene expression involved in biofilm production. The present work aimed to disrupt the production of an autoinducer (AI) factor involved in interspecies communication between S. aureus and P. aeruginosa through the fabrication of cationic liposomes encapsulated with antisense oligonucleotides. The liposomes themselves were synthesized via a microfluidic system to ensure uniform particle size distribution conducive to bacterial biofilm uptake. Furthermore, the various liposome samples exhibited favourable encapsulation efficiency of nucleic acids for effective delivery into Gram-positive and Gram-negative co-cultured biofilms. While antisense oligonucleotide (ASO)-loaded liposomes demonstrated a decrease in the production of an AI factor, there was no significant decrease in the biofilm production; nonetheless, this technology represents a steppingstone in the development of liposome-based strategies for delivery of nucleic acids to bacterial biofilms with the potential to expand to other pathogenic bacterial biofilms.