Intracellular delivery of genetic material is a potentially powerful therapeutic approach for the treatment of genetic diseases. However, the scarcity of biocompatible delivery systems is a tremendous barrier for the application of nucleic acid therapy in the clinic. Herein, we successfully created biocompatible nucleic acid delivery systems based on cationic lipids consisting of alternatively linked ornithine residues in the head group (denoted DoGo lipids). Transfection of the pcDNA3-eGFP plasmid into cells using DoGo lipids resulted in significant transfection efficiency without showing any apparent cytotoxicity. Meanwhile, DoGo lipids efficiently delivered siRNA to cancer cell lines and induced profound RNAi activity at a siRNA concentration as low as 5 nM. DoGo lipid driven delivery of a siRNA against polo-like kinase 1 (Plk1) in cancer cells induced significant morphological changes in the cell and the nucleus due to cell cycle arrest and inhibition of cell proliferation, a phenotype resulting from the decreased Plk1 protein level. Our findings demonstrate that DoGo lipids have great potential in clinical application for gene based therapy.
The pro-inflammatory polarization of microglia after stroke is one of the major causes of secondary brain injury. Downregulation of the gene involved in canonical inflammatory pathways in glial cells can exert neuroprotective effects via inhibiting the release of pro-inflammatory factors. In this study, we functionalized DoGo lipids with mannose, the ligand of the mannose receptor (MR) that is expressed in microglia, and evaluated the MR-mediated cellular internalization of DoGo lipid nanoparticles (denote M3) carrying siRNA against TLR4 in BV2 cells in vitro. We confirmed that siTLR4/M3 complexes were specifically internalized by BV2 cells in a MR-dependent manner, and the treatment of oxygen glucose deprivation (OGD)-treated BV2 cells with siTLR4/M3 complexes resulted in remarkable silencing of TLR4, and induced downregulated M1 polarization and upregulated M2 polarization markers. Collectively, our data suggest that the M3 lipoplex is a promising microglia-targeting siRNA delivery agent.
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