Fully homogeneous facial amphiphiles consisting in a cyclodextrin (CD) platform onto which a polycationic cluster and a multi-tail hydrophobic moiety have been installed (polycationic amphiphilic CDs; paCDs) self-organized in the presence of plasmid DNA to form nanometric complexes (CDplexes) which exhibit broad-range transfection capabilities. We hypothesized that biorecognizable moieties located at the hydrophilic rim in the CD scaffold would be exposed at the surface of the corresponding nanoparticles after DNA-promoted aggregation, endowing the system with molecular recognition abilities towards cell receptors. This concept has been demonstrated by developing an efficient synthetic strategy for the preparation of multivalent polycationic glyco-amphiphilic CDs (pGaCDs). Self-assembled nanoparticles obtained from mannosylated pGaCDs and pDNA (average hydrodynamic diameter 80 nm) have been shown to be specifically recognized by mannose-specific lectins, including concanavalin A (Con A) and the human macrophage mannose receptor (MMR). Further macrophage adhesion studies indicated that unspecific binding, probably due to electrostatic interactions with negatively charged cell membrane components, can also operate. The relative specific versus non-specific internalization is dependent on the pGaCD:pDNA proportion, being optimal at a protonable nitrogen/phosphate (N/P) ratio of 5. The resulting GlycoCDplexes were shown to specifically mediate transfection in Raw 264.7 (murine macrophage) cells expressing the mannose-fucose receptor in vitro. FACS experiments confirmed that transfection using these nanoparticles is mannose-dependent, supporting the potential of the approach towards vectorized gene delivery.

International audienceExperiments of magnetolysis, i.e., destruction of cells induced with magnetic particles (MPs) submitted to the application of a magnetic field, were conducted on HepG2 cancer cells. We herein demonstrate the usefulness of combining anisotropic MPs with an alternative magnetic field in magnetolysis. Thus, the application of an alternative magnetic field of low frequency (a few Hertz) in the presence of anisotropic, submicronic particles allowed the destruction of cancer cells "in vitro". We also show that a constant magnetic field is far less efficient than an oscillating one. Moreover, we demonstrate that, at equal particle volume, it is much more efficient to utilize spindle shaped particles rather than spherical ones. In order to get deeper insight into the mechanism of magnetolysis experiments, we performed a study by AFM, which strongly supports that the magnetic field induces the formation of clusters of particles becoming then large enough todamage cell membranes

The determination of the viscoelastic properties of cells by atomic force microscopy (AFM) is mainly realized by looking at the relaxation of the force when a constant position of the AFM head is maintained or at the evolution of the indentation when a constant force is maintained. In both cases the analysis rests on the hypothesis that the motion of the probe before the relaxation step is realized in a time which is much smaller than the characteristic relaxation time of the material. In this paper we carry out a more general analysis of the probe motion which contains both the indentation and relaxation steps, allowing a better determination of the rheological parameters. This analysis contains a correction of the Hertz model for large indentation and also the correction due to the finite thickness of the biological material; it can be applied to determine the parameters representing any kind of linear viscoelastic model. This approach is then used to model the rheological behavior of one kind of cancer cell called Hep-G2. For this kind of cell, a power law model does not well describe the low and high frequency modulus contrary to a generalized Maxwell model.

A collection of homologous monodisperse facial amphiphiles consisting of an α-, β- or γ-cyclodextrin (α, β or γCD) platform exposing a multivalent display of cationic groups at the primary rim and bearing hexanoyl chains at the secondary hydroxyls have been prepared to assess the influence of the cyclooligosaccharide core size in their ability to complex, compact and protect pDNA and in the efficiency of the resulting nanocondensates (CDplexes) to deliver DNA into cells and promote transfection in the presence of serum. All the polycationic amphiphilic CDs (paCDs) were able to self-assemble in the presence of the plasmid and produce transfectious nanoparticles at nitrogen/phosphorous ratios ≥5. CDplexes obtained from βCD derivatives generally exhibited higher transfection capabilities, which can be ascribed to their ability to form inclusion complexes with cholesterol, thereby enhancing biological membrane permeability. The presence of thiourea moieties as well as increasing the number of primary amino groups then favour cooperative complexation of the polyphosphate chain, enhancing the stability of the complex and improving transfection. In the α and γCD series, however, only the presence of tertiary amino groups in the cationic clusters translates into a significant improvement of the transfection efficiency, probably by activating endosome escape by the proton sponge mechanism. This set of results illustrates the potential of this strategy for the rational design and optimisation of nonviral gene vectors.

Monodisperse amphiphilic oligoethyleneimine (OEI)-β-cyclodextrin (βCD) clusters have been prepared, and their potential as gene delivery systems has been evaluated in comparison with a nonamphiphilic congener. The general prototype incorporates tetraethyleneimine segments linked to the primary rim of βCD through either triazolyl or thioureidocysteaminyl connectors. Transfection efficiency data for the corresponding CD:pDNA nanocomplexes (CDplexes) in BNL-CL2 murine hepatocytes evidenced the strong beneficial effect of facial amphiphilicity.

A tetrawalled and an octawalled molecular umbrella conjugate of amphotericin B (AmB) have been synthesized. Both conjugates exhibit high water solubility, a low tendency to aggregate, negligible hemolytic activity at 100 μM, and an ability to release a derivative of AmB under reducing conditions that exhibits high antifungal activity. Whereas the larger, octawalled conjugate shows slight adsorption to liposomal membranes and an ability to cross them by passive transport, the tetrawalled analogue shows significant adsorption and much lower bilayer transport activity. The potential of molecular umbrella–AmB conjugates as therapeutic agents is briefly discussed.

Pancreatic cancer is one of the most aggressive and devastating human malignancies. There is an urgent need for more effective therapy for patients with advanced disease. In this context, genetic therapy potentially represents a rational new approach to treating pancreatic cancer, which could provide an adjunct to conventional options. Because of the promise of recombinant SV40 vectors, we tested their ability to deliver a transgene, and to target a transcript, so as to inhibit pancreatic tumors growth in vivo. BxPC3 and Capan-1 cells were efficiently transduced using SV40 vectors without selection, as compared to synthetic vectors PEI. SV40 vectors were as efficient as adenoviral vectors, and provided long-term transgene expression. Next, we devised a SV40-derived, targeted gene therapy approach of pancreatic cancer, by combining hTR tumor-specific promoter with sst2 somatostatin receptor tumor-suppressor gene. In vitro cell proliferation was strongly impaired following administration of SV(hTR-sst2). SV40-derived sst2-mediated antiproliferative effect was dependent on the local production of somatostatin. In vivo, intratumoral gene transfer of sst2 using rSV40 vectors resulted in a marked inhibition of Capan-1 tumor progression, and proliferation. These results represent the initial steps toward a novel approach to the gene therapy of pancreatic cancer using SV40 as a vector.

The incorporation of carbohydrate functional elements in the architecture of polycationic amphiphilic cyclodextrins (paCDs) provides glycosylated paCDs (pGaCDs) that form transfectious nanocomplexes (glycoCDplexes) with pDNA. In this study, we aimed at elucidating the internalization mechanisms at play and their incidence in transfection efficiency for glycoCDplexes formulated with 6-amino-6-deoxy-b-Dglucopyranosyl-appended pGaCDs in comparison with mannosylated and non-glycosylated congeners.Preliminary data showed a relatively high uptake of the 6-aminoglucosylated nanocomplexes by BNL-CL2 hepatocytes that correlated with a strong affinity towards the galactose-specific peanut agglutinin (PNA) lectin, suggesting that the galactose-binding asialoglycoprotein receptor at the surface of hepatocytes might be involved in glycoCDplex internalization. Transfection kinetics, internalization rates and protein expression data in BNL-CL2 ASGPR-expressing cells and COS-7 ASGPR-devoid epithelial cells in the absence and presence of different inhibitors of clathrin-dependent (chlorpromazine), caveolae-dependent (genistein) and macropinocytosis (amiloride) endocytic routes evidenced significant differences in cell uptake pathways and fate of glycoCDplexes as compared with CDplexes. Most importantly, such differences were dependent on the cell type and on the carbohydrate coating moiety.Clathrin-mediated uptake in BNLCL-2 cells is particularly favored for the 6-amino-6-deoxyglucose CDplexes, supporting the interplay of specific recognition phenomena. Competitive uptake and transfection experiments conducted in the presence of asialofetuin or of a polyclonal ASGPR-antibody, as well as siRNA-mediated ASGPR-specific gene knockdown, supported the involvement of ASGPR, firmly demonstrating the dual role of the 6-amino-6-deoxyglucose motif as DNA and lectin receptor ligand. The results reinforce the use of carbohydrates in glycoCDplexes to modulate cellular uptake and transfection capabilities in a cell-dependent manner.