A photoresponsive LPD system developed

19 July 2018:

CNBP researchers have published a paper reporting on  the development of a novel photoresponsive liposome-polycation-DNA (LPD) platform. Lead author on the paper was Wenjie Chen (pictured).

Journal: Journal of Materials Chemistry B.

Publication title: Photoresponsive endosomal escape enhances gene delivery using liposome-polycation-DNA (LPD) nanovector.

Authors: Wenjie Chen, Wei Deng, Xin Xu, Xiang Zhao, Jenny Nhu Vo, Ayad G. Anwer, Thomas C. Williams, Haixin Cui, Ewa M. Goldys.

Abstract: Lipid-based nanocarriers with stimuli responsiveness have been utilized as controlled release systems for gene/drug delivery applications. In our work, by taking advantage of high complexation capbility of polycations and the light triggered property, we designed a novel photoresponsive liposome-polycation-DNA (LPD) platform. This LPD carrier incorporates verteporfin (VP) in lipid bilayers and the complex of polyethylenimine (PEI)/plasmid DNA (pDNA) encoding EGFP (polyplex) in the central cavities of liposomes. The liposomes were formulated with cationic lipids, PEGylated neutral lipids and cholesterol molecules, which improve their stability and cellular uptake in the serum-containing media. We evaluated the nanocomplex stability by monitoring size changes over six days, and the celluar uptake of nanocomplex by imaging the intracellular route. We also demonstrated light triggered the cytoplasmic release of pDNA upon irradiation with a 690 nm LED light source. Furthermore this light triggered mechanism has been studied at subcellular level. The activated release is driven by the generation of reactive oxygen species (ROS) from VP after light illumination. These ROS oxidize and destabilize the liposomal and endolysosomal membranes, leading to the release of pDNA into the cytosol and subsequent gene transfer activities. Light-triggered endolysosomal escape of pDNA at different time points was confirmed by quantitative analysis of colocalization between pDNA and endolysosomes. The increased expression of the reporter EGFP in human colorectal cancer cells was also quantified after light illumination at various time points. The efficiency of this photo-induced gene transfection was demonstrated to be more than double compared to non-irradiated controls. Additionally, we observed reduced cytotoxicity of the LPDs compared with the polyplexes alone. This study have thus shown that light-triggered and biocompatible LPDs enable improved control of efficient gene delivery which will be beneficial for future gene therapies.