Enhanced Gene Transfection in Macrophages by Histidine-Conjugated Mannosylated Cationic Liposomes

Abstract

The use of non-viral carriers has attracted great interest for in vivo gene delivery since they are free from some of the risks inherent in these systems compared with viral vectors. Furthermore, non-viral carriers are easier to prepare and to modify by chemical approaches. To achieve cell-selective targeted in vivo gene transfection, a number of receptor-mediated non-viral carriers have been developed. 1) Antigen presenting cells (APCs) such as macrophages and dendritic cells are important targets for DNA vaccine therapy.2,3) It is known that the mannose receptor is a 175 kDa protein expressed on the surface of APCs and it recognizes the terminal of mannose groups. To date, mannose modified non-viral vectors, including cationic liposomes, 4,5) polyethyleneimine, 6,7) dendrimers, 8) and chitosan 9,10) have been reported to achieve targeted gene delivery into APCs via mannose receptor-mediated endocytosis.Recently, we reported that mannosylated cationic liposomes modified with cholesten-5-yloxy-N-(4-((1-imino-2-Dthiomannosylethyl)amino)butyl)formamide (Man-C4-Chol) enhanced DNA vaccine potency through efficiently targeted gene delivery to APCs in mice. 11,12) However, the degradation of plasmid DNA in the lysosomes after their incorporation into cells is a rate-limiting step for transfection in macrophages. 13,14) Therefore, an escape path from the endosomes needs to be introduced into our mannosylated cationic liposomes for more efficient gene transfer in macrophages. Histidine is known to have pH-buffering capacity under the slightly acidic conditions such as are found in lysosomes and, accordingly, it could enhance the cytoplasmic distribution of plasmid DNA before degradation in lysosomes.15) More recently, we have demonstrated that histidine-conjugated galactosylated liposomes, which possess pH-buffering capacity, can provide efficient hepatocyte-selective gene transfer in human hepatoma HepG2 cells. 16) In this study, we extended our earlier investigations 5,16) and a pH-sensitive mannosylated cholesterol derivative, ManHis-C4-Chol (Chart 1), which possesses histidine residues, containing lipoplexes (Man-His-lipoplexes) was characterized for transfection both in vitro and in vivo. Man-Hislipoplexes possess multi-functional properties for efficient transfection into macrophages, i.e., i) cholesterol for their stable incorporation into cationic liposomes, ii) a mannose group for recognition by mannose receptors in macrophages, iii) an imino group for binding plasmid DNA without loss of the cationic nature of the cationic liposomes, iv) a histidine group to allow an endosomal escape by the pH-buffering capacity. Since the physicochemical properties of mannosylated lipoplexes are also important to achieve cell-selective gene transfection, 1) the His group was directly introduced into our previously synthesized mannosylated cholesterol derivative, Man-C4-Chol; consequently, a pH-buffering capacity could be introduced in the formulation without any significant change into the optimal physicochemical properties.Fi...

Targeted Liposomal Drug Delivery to Monocytes and Macrophages

“…Mannosylation has been achieved by the incorporation of ligands such as alkyl mannosides [70], Cholesten-5-yloxy- N -(4-((1-imino-2- α -thioglycosylethyl)amino)butyl)formamide (Mann-C4-Chol) [33, 74, 75, 77], Mann-His-C4-Chol [77], Man 2 DOG [34], 4-aminophenyl-a-D-mannopyranoside [5, 69], and manntriose (Man3)-DPPE [35, 36, 71] into the liposome formulations or by liposome coating with p -aminophenyl- α -D-mannopyranoside [6]. We have prepared a range of mannosylated liposome, and quantified the increase in cell association with a macrophage-like cell model, differentiated THP-1 cells.…”

Advancing Nonviral Gene Delivery: Lipid- and Surfactant-Based Nanoparticle Design Strategies

“…Mannose receptor-mediated gene transfer, a macrophage targeting method, was carried out by intravenously injecting plasmid DNA complexed with a mannosylated cholesterol derivative. These complexes selectively accumulated in the liver, as measured by the amount of 32 P-labelled DNA, and achieved the highest protein expression compared with nonmannosylated complexes [119]. Similarly, galactose-modified liposomes were also used to transfect DNA into HepG2 and HuH-6 cells, which express asialoglycoprotein receptors, resulting in a three-to four-fold rise in transfection efficiency in theses cells compared with the negative controls [120].…”

Lipid‐based gene delivery to macrophage mitochondria for atherosclerosis therapy

“…A number of known macrophage surface receptors have been considered as potential targets for molecular therapeutic approaches 10,52,53 . NPs containing ligands for these receptors demonstrate significantly higher selectivity and transfection efficiency 54–56 . The mannose receptor (MR), which is a C‐type lectin I transmembrane protein, is believed to be a promising target for nanocarriers 57 .…”