Macrophage mannose receptor-specific gene delivery vehicle for macrophage engineering.

Macrophages are the most plastic cells in the hematopoietic system and they exhibit great functional diversity. They have been extensively applied in anti-inflammatory, anti-fibrotic and anti-cancer therapies. However, the application of macrophages is limited by the efficiency of their engineering. The macrophage mannose receptor (MMR, CD206), a C-type lectin receptor, is ubiquitously expressed on macrophages and has a high affinity for mannose oligosaccharides. In the present study, we developed a novel non-viral vehicle with specific affinity for MMR. Mannan was cationized with spermine at a grafted ratio of ∼12% to deliver DNA and was characterized as a stable system for delivery. This spermine-mannan (SM)-based delivery system was evaluated as a biocompatible vehicle with superior transfection efficiency on murine macrophages, up to 28.5-fold higher than spermine-pullulan, 11.5-fold higher than polyethylenimine and 3.0-fold higher than Lipofectamine™ 2000. We confirmed that the SM-based delivery system for macrophages transfection was MMR-specific and we described the intracellular transport of the delivery system. To our knowledge, this is the first study using SM to demonstrate a mannose receptor-specific gene delivery system, thereby highlighting the potential of a novel specific non-viral delivery vehicle for macrophage engineering.

Co-transfection gene delivery of dendritic cells induced effective lymph node targeting and anti-tumor vaccination.

PURPOSE: Successful genetically engineered Dendritic Cell (DC) can enhance DC's antigen presentation and lymph node migration. The present study aims to genetically engineer a DC using an efficient non-viral gene delivery vector to induce a highly efficient antigen presentation and lymph node targeting in vivo. METHODS: Spermine-dextran (SD), a cationic polysaccharide vector, was used to prepare a gene delivery system for DC engineering. Transfection efficiency, nuclear trafficking, and safety of the SD/DNA complex were evaluated. A vaccine prepared by engineering DC with SD/gp100, a plasmid encoding melanoma-associated antigen, was injected subcutaneously into mice to evaluate the tumor suppression. The migration of the engineered DCs was also evaluated in vitro and in vivo. RESULTS: SD/DNA complex has a better transfection behavior in vitro than commercially purchased reagents. The DC vaccine co-transfected with plasmid coding CCR7, a chemokine receptor essential for DC migration, and plasmid coding gp100 displayed superior tumor suppression than that with plasmid coding gp100 alone. Migration assay demonstrated that DC transfected with SD/CCR7 can promote DC migration capacity. CONCLUSIONS: The study is the first to report the application of nonviral vector SD to co-transfect DC with gp100 and CCR7-coding plasmid to induce both the capacity of antigen presentation and lymph node targeting.

Optimization and internalization mechanisms of PEGylated adenovirus vector with targeting peptide for cancer gene therapy.

We have previously developed a novel adenovirus vector (Adv) that targeted tumor tissues/vasculatures after systemic administration. The surface of this Adv is conjugated with CGKRK tumor homing peptide by the cross-linking reaction of polyethyleneglycol (PEG). In this study, we showed that the condition of PEG modification was important to minimize the gene expression in normal tissues after systemic treatment. When Adv was modified only with PEG-linked CGKRK, its luciferase expression was enhanced even in the liver tissue, as well as the tumor tissue. However, in the reaction with the mixture of non-cross-linking PEG and PEG-linked CGKRK, we found out that the best modification could suppress its gene expression in the liver, without losing that in the tumor. We also studied the internalization mechanisms of CGKRK-conjugated Adv. Results suggested that there is a specific interaction of the CGKRK peptide with a receptor at the cell surface enabling efficient internalization of CGKRK-conjugated Adv. The presence of cell-surface heparan sulfate is important receptor for the cellular binding and uptake of CGKRK-conjugated Adv. Moreover, macropinocytosis-mediated endocytosis is also important in endocytosis of CGKRK-conjugated Adv, aside from clathrin-mediated and caveolae-mediated endocytosis. These results could help evaluate the potentiality of CGKRK-conjugated Adv as a prototype vector with suitable efficacy and safety for systemic cancer gene therapy.

Gene-carried chitosan-linked polyethylenimine induced high gene transfection efficiency on dendritic cells.

A dendritic cell (DC) networking system has become an attractive approach in cancer immunotherapy. Successful DC gene engineering depends on the development of transgene vectors. A cationic polymer, chitosan-linked polyethylenimine (PEI) (CP), possessing the advantages of both PEI and chitosan, has been applied in nonviral transfection of DCs. Physicochemical evaluation showed that CP/DNA complexes could form cationic nanoparticles. Compared with DCs transfected with commercial reagent, Lipofectamine2000, it showed higher transfection efficiency and lower cytotoxicity when DCs were transfected with CP/DNA complexes. A nuclear trafficking observation of CP/DNA complexes by a confocal laser scanning microscope further revealed that the CP could help DNA enter into the cytoplasm and finally into the nucleus of a DC. Finally, vaccination of DCs transfected with CP/DNA encoding gp100 slightly improved resistance to the B16BL6 melanoma challenge. This is the first report that CP polymer is used as a nonviral vector for DC gene delivery and DC vaccine. Essentially, these results might be helpful to design a promising nonviral vector for DC gene delivery.

Gene carriers and transfection systems used in the recombination of dendritic cells for effective cancer immunotherapy.

Dendritic cells (DCs) are the most potent antigen-presenting cells. They play a vital role in the initiation of immune response by presenting antigens to T cells and followed by induction of T-cell response. Reported research in animal studies indicated that vaccine immunity could be a promising alternative therapy for cancer patients. However, broad clinical utility has not been achieved yet, owing to the low transfection efficiency of DCs. Therefore, it is essential to improve the transfection efficiency of DC-based vaccination in immunotherapy. In several studies, DCs were genetically engineered by tumor-associated antigens or by immune molecules such as costimulatory molecules, cytokines, and chemokines. Encouraging results have been achieved in cancer treatment using various animal models. This paper describes the recent progress in gene delivery systems including viral vectors and nonviral carriers for DC-based genetically engineered vaccines. The reverse and three-dimensional transfection systems developed in DCs are also discussed.