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Here we demonstrate the ability of mannosylated liposomes (ML) targeted to mannose receptors (MR) to perform the targeted delivery of model plasmid DNA encoding EGFP and total tumour RNA into murine bone-marrow-derived dendritic cells (DCs) and enhance the efficiency of anti-tumour response triggered by these DCs in murine melanoma model. ML consist of cationic lipid 2X3 (1,26-Bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosan tetrahydrochloride), helper lipid DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine), and 2.5, 5 or 10% mol. of novel mannosylated lipoconjugates. In the structure of lipoconjugates D-mannose was attached to ditetradecylglycerol residue via succinyl (lipoconjugate 1) or diethylsquarate (lipoconjugate 2) linker groups. ML spontaneously form complexes with plasmid DNA and RNA due to electrostatic interaction between positively charged lipid amino group and negatively charged phosphate of nucleic acids. ML demonstrated the benefit in transfection efficiency (TE) of pDNA into DC progenitors and immature DCs in comparison with the control liposomes at low N/P (nitrogen to phosphate) ratios (1/1 and 2/1) but not at high N/P ratios where the TE was comparable with control liposomes. Moreover, ML at low N/P were more effective in RNA delivery into immature DCs in comparison with DC progenitors. At high N/P ratios liposomal formulations containing 5 and 10% mol. of mannosylated lipoconjugate 2 with diethylsquarate linker were the most effective (up to 50% of transfected cells). DCs transfected ex vivo with ML/melanoma B16 RNA complexes after i.v. injection into mice caused five- to six-fold inhibition of melanoma lung metastasis number. Moreover, the i.v. injection of ML/melanoma B16 RNA complexes into mice induced generation of the melanoma B16-specific cytotoxic T-lymphocytes, which were two-fold more efficient in B16 cell killing than those from control liposome group., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Here we report on the application of cationic liposomes formed by new cationic lipids and the lipid-helper DOPE (dioleoylphosphatidylethanolamine) for the transfection of plasmid DNA and mRNA into dendritic cells (DCs) progenitors and immature DCs of bone-marrow origin in vitro and the use of these DCs to induce the suppression of B16 melanoma metastases in vivo. The cationic lipids contain one (X2, S1, S2 and S3) or two (2X3) cholesterol residues or long-chain hydrocarbon substituent (2D3) linked with spermine. Data show that liposomes 2X3-DOPE, 2D3-DOPE, X2-DOPE and S2-DOPE display high transfection efficiency in respect to DNA (30-47% of DC progenitors and up to 57% of immature DC were transfected) and RNA (up to 57% of cells were transfected). The studied lipids exhibited an efficiency of DNA and RNA delivery in DCs several times higher in comparison with Lipofectamine 2000. Observed ex vivo the higher transfection efficiencies of DCs with mRNAs encoding of a set of tumor-associated antigens provided by cationic liposomes 2X3-DOPE and 2X2-DOPE corresponded to a 3-5 fold suppression of metastasis number in a model of murine B16 melanoma in vivo. The injection into mice of these pulsed DCs resulted in a slight pro-inflammatory response which was balanced by the positive effect of the antitumor cytokine production induced by the DCs. The obtained data show that the novel spermine-based polycationic lipids can be applied in the preparation of antitumor DC-based vaccine., (Copyright © 2011 Elsevier B.V. All rights reserved.)

New polycationic lipids corresponding to the two different classes of amphiphiles ("head-tail" and "gemini") were designed and used as components of non-viral gene delivery systems. The hydrophobic domain of lipids is based on the cholesterol residue and the hydrophilic one--on the naturally occurring polyamine--spermine. Ester and carbamate linker groups as well as oligomethylene spacers of various lengths were used to connect cholesterol and spermine motifs in order to estimate the structure-activity relationships of novel polycationic lipids and to determine an effective and safe transfectant suitable for the delivery of different nucleic acids. The cationic liposomes composed of the synthesized polycationic lipids and DOPE provided delivery of FITC-labeled oligonucleotide, plasmid DNA and siRNA into HEK293 cells with an efficiency significantly higher than that of Lipofectamine 2000. We found that the transfection activity of polycationic lipids is influenced by a linker type, a spacer length and the amount of cholesterol residues. The lipid containing two cholesterol units, carbamate linker and spacer of six methylene groups demonstrated the best in vitro transfection results among other analogues tested and was defined as a promising candidate for further transfection studies to be hold in vivo., (Copyright © 2011 Elsevier B.V. All rights reserved.)