Poly(lipoic acid)-based nanoparticles as a new therapeutic tool for delivering active molecules.

Pluronic-coated polylipoic acid-based nanoparticles (F127@PLA-NPs) have great potential as biodegradable nanovectors for delivering active molecules to different organs in complex diseases. In this study we describe the in vivo biodistribution, safety and ability to deliver molecules of F127@PLA-NPs in healthy rats following intravenous administration. Adult rats were injected with 10 mg/kg of rhodamine B-labeled F127@PLA-NPs, and NPs fluorescence and MFI rate were measured by confocal microscopy in whole collected organs. The NPs accumulation rate was maximal in the heart, compared to the other organs. At the cellular level, myocytes and kidney tubular cells showed the highest NPs uptake. Neither histopathological lesion nor thrombogenicity were observed after NPs injection. Finally, F127@PLA-NPs were tested in vitro as miRNAs delivery nanosystem, and they showed good ability in targeting cardiomyocytes. These results demonstrated that our F127@PLA-NPs constitute a biological, minimally invasive and safe delivery tool targeting organs and cells, such as heart and kidney.

Poly(lipoic acid)-Based Nanoparticles as Self-Organized, Biocompatible, and Corona-Free Nanovectors.

Herein we present an innovative approach to produce biocompatible, degradable, and stealth polymeric nanoparticles based on poly(lipoic acid), stabilized by a PEG-ended surfactant. Taking advantage of the well-known thiol-induced polymerization of lipoic acid, a universal and nontoxic nanovector consisted of a solid cross-linked polymeric matrix of lipoic acid monomers was prepared and loaded with active species with a one-step protocol. The biological studies demonstrated a high stability in biological media, the virtual absence of "protein" corona in biological fluids, the absence of acute toxicity in vitro and in vivo, complete clearance from the organism, and a relevant preference for short-term accumulation in the heart. All these features make these nanoparticles candidates as a promising tool for nanomedicine.

The peculiar N- and (-termini of trichogin GA IV are needed for membrane interaction and human cell death induction at doses lacking antibiotic activity.

Peptaibiotics, non-ribosomally synthetized peptides from various ascomycetes, are uniquely characterized by dialkylated a-amino acids, a rigid heli cal conformation, and membrane permeation properties. Although generally considered as antimicrobial peptides, peptaibiotics may display other toxicological properties, and their function is in many cases unknown. With the goal to define the biological activity and selectivity of the peptaibiotictrichogin GA IV from the human opportunist Trichodenna longibrachiatum we analyzed its membrane interaction,cytotoxic activity and antibacterial effect. Trichogin GA IV effectively killed several types of healthy and neoplastic human cells at doses (EC 50%= 4-6 ~) lacking antibiotic effects on both Gram- and Gram+ bacteria(MIC > 64 ~ ). The peptaibiotic distinctive (-terminal primary alcohol was found to cooperate with theN-terminal n-octanoyl group to permeate the membrane phospholipid bilayer and to mediate effective binding and active endocytosis of trichogin GA IV in eukaryotic cells, two steps essential for cell death induction.Replacement of one Gly with Lys plus the simultaneous esterification of the (-terminus, strongly increased trichogin GA IV anti-Gram+ activity (MIC 1-4 ~ ). but further mitigated its cytotoxicity on human cells.

Water-soluble peptide-coated nanoparticles: control of the helix structure and enhanced differential binding to immune cells.

The stabilizing action of C(α)-tetrasubstituted α-amino acids inserted into a sequence of short peptides allowed for the first time the preparation of water-soluble nanoparticles of different materials coated with a helix-structured undecapeptide. This peptide coating strongly favors nanoparticle uptake by human immune system cells.

Tumor-facing hepatocytes significantly contribute to mild hyperthermia-induced targeting of rat liver metastasis by PLGA-NPs.

The effect of mild hyperthermia (MHT) on nanoparticle (NP) accumulation in rat model liver metastasis and the contribution of neoplastic and non-neoplastic cells were characterized. CdSe/ZnS QD-doped poly(lactic-co-glycolic acid) (PLGA) NPs (155 ±â€¯10 nm) were delivered via the ileocolic vein to metastatic livers 15 min after localized MW irradiation (1 min, 41 °C) or in normothermia (37 °C, NT). Quantitative analysis of tissue sections by confocal fluorescence microscopy 1 h after NP injection showed no NP tumor accumulation in NT. On the contrary, MHT increased NP association with tumor, compared to normal tissue. Counterstaining of specific markers showed that the MHT effect is due to an increased NP endocytosis not only by tumor cells, but also by hepatocytes at the growing tumor edge and, to a minor extent, by tumor-associated macrophages. High-NP capturing hepatocytes, close to the tumor, may be a relevant phenomenon in MHT-induced increased targeting of NPs to liver metastasis, influencing their therapeutic efficacy.

Form Matters: Stable Helical Foldamers Preferentially Target Human Monocytes and Granulocytes.

Some hybrid foldamers of various length, all containing the (4R,5S)-4-carboxy-5-methyloxazolidin-2-one (d-Oxd) moiety alternating with an l-amino acid (l-Val, l-Lys, or l-Ala), were prepared in order to study their preferred conformations and to evaluate their biological activity. Surprisingly, only the longer oligomers containing l-Ala fold into well-established helices, whereas all the other oligomers give partially unfolded turn structures. Nevertheless, they all show good biocompatibility, with no detrimental effects up to 64 µm. After equipping some selected foldamers with the fluorescent tag rhodamine B, a quantitative analysis was performed by dose- and time-response fluorescence-activated cell sorting (FACS) assays with human HeLa cells and primary blood lymphocytes, granulocytes, and monocytes. Among the cell types analyzed, the oligomers associated with monocytes and granulocytes with greatest efficacy, still visible after 24 h incubation. This effect is even more pronounced for foldamers that are able to form stable helices.

Plant polyphenols inhibit VacA, a toxin secreted by the gastric pathogen Helicobacter pylori.

VacA is a major virulence factor of the widespread stomach-dwelling bacterium Helicobacter pylori. It causes cell vacuolation and tissue damage by forming anion-selective, urea-permeable channels in plasma and endosomal membranes. We report that several flavone derivatives and other polyphenols present in vegetables and plants inhibit ion and urea conduction and cell vacuolation by VacA. Red wine and green tea, which contain many of the compounds in question, also potently inhibit the toxin. These observations suggest that polyphenols or polyphenol derivatives may be useful in the prevention or cure of H. pylori-associated gastric diseases.

Targeted delivery of photosensitizers: efficacy and selectivity issues revealed by multifunctional ORMOSIL nanovectors in cellular systems.

PEGylated and non-PEGylated ORMOSIL nanoparticles prepared by microemulsion condensation of vinyltriethoxy-silane (VTES) were investigated in detail for their micro-structure and ability to deliver photoactive agents. With respect to pure silica nanoparticles, organic modification substantially changes the microstructure and the surface properties. This in turn leads to a modulation of both the photophysical properties of embedded photosensitizers and the interaction of the nanoparticles with biological entities such as serum proteins. The flexibility of the synthetic procedure allows the rapid preparation and screening of multifunctional nanosystems for photodynamic therapy (PDT). Selective targeting of model cancer cells was tested by using folate, an integrin specific RGD peptide and anti-EGFR antibodies. Data suggest the interference of the stealth-conferring layer (PEG) with small targeting agents, but not with bulky antibodies. Moreover, we showed that selective photokilling of tumour cells may be limited even in the case of efficient targeting because of intrinsic transport limitations of active cellular uptake mechanisms or suboptimum localization.

In vitro and in vivo characterization of temoporfin-loaded PEGylated PLGA nanoparticles for use in photodynamic therapy.

AIMS: In this study we evaluated temoporfin-loaded polyethylene glycol (PEG) Poly-(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) as a new formulation for potential use in cancer treatment. MATERIALS & METHODS: NPs were characterized for their photophysical properties, temoporfin release, cellular uptake and intracellular localization, and dark and photocytotoxicities of temoporfin by using A549, MCF10A neoT and U937 cell lines. In vivo imaging was performed on athymic nude-Foxn1 mice. RESULTS: Temoporfin was highly aggregated within the NPs and the release of temoporfin monomers was faster from PEGylated PLGA NPs than from non-PEGylated ones. PEGylation significantly reduced the cellular uptake of NPs by the differentiated promonocytic U937 cells, revealing the stealth properties of the delivery system. Dark cytotoxicity of temoporfin delivered by NPs was less than that of free temoporfin in standard solution (Foscan(®), Biolitec AG [Jena, Germany]), whereas phototoxicity was not reduced. Temoporfin delivered to mice by PEGylated PLGA NPs exhibits therapeutically favorable tissue distribution. CONCLUSION: These encouraging results show promise in using PEGylated PLGA NPs for improving the delivery of photosensitizers for photodynamic therapy.

Proinflammatory effects of bare and PEGylated ORMOSIL-, PLGA- and SUV-NPs on monocytes and PMNs and their modulation by f-MLP.

AIMS: We wanted to test the proinflammatory effects of vinyltriethoxysilane-based organically modified silica nanoparticles (ORMOSIL-NPs) in vitro on blood leukocytes. MATERIALS & METHODS: Cell selectivity, cytokines/chemokines and O(2) (-) production were analyzed using nonpolyethylene glycol (PEG)ylated and PEGylated ORMOSIL-NPs, poly(lactic-co-glycolic acid) (PLGA)-NPs and small unilamellar vesicles (SUV)-NPs. RESULTS: ORMOSIL-NPs mostly bound to monocytes while other NPs to all leukocyte types similarly. Cell capture of PEGylated-NPs decreased strongly (ORMOSIL), moderately (PLGA) and weakly (SUV). Bare ORMOSIL-NPs effectively stimulated the production of IL-1ß/IL-6/TNF-α/IL-8 by monocytes and of IL-8 by polymorphonuclear leukocytes (PMNs). NP PEGylation inhibited such effects only partially. Formyl-methionine-leucine phenylalanine (f-MLP) further increased the release of cytokines/chemokines by monocytes/PMNs primed with bare and PEGylated ORMOSIL-NPs. PEGylated SUV-NPs, bare and PEGylated ORMOSIL- and PLGA-NPs sensitize PMNs and monocytes to secrete O(2) (-) upon f-MLP stimulation. CONCLUSION: ORMOSIL-NPs are preferentially captured by circulating monocytes but stimulate both monocytes and PMNs per se or by sensitizing them to another agonist (f-MLP). PEG-coating confers stealth effects but does not completely eliminate leukocyte activation. Safe nanomedical applications require the evaluation of both intrinsic and cooperative proinflammatory potential of NPs.

Procoagulant properties of bare and highly PEGylated vinyl-modified silica nanoparticles.

AIMS: Undesired alterations of the blood clotting balance may follow the intravascular injection of nanotherapeutics/diagnostics. Here, we tested the procoagulant activity of synthetic amorphous silica (SAS) and organically modified silica (ORMOSIL) nanoparticles (NPs) and whether a high-density polyethylene glycol coating minimizes these effects. MATERIALS & METHODS: Hageman factor- and tissue factor-dependent activation of human blood/plasma coagulation, and binding to human monocytes, endothelial cells and platelets were quantified in vitro using naked and PEGylated ORMOSIL-NPs. Their effects were compared with those of SAS-NPs, present in many industrial products, and of poly(lactic-co-glycolic acid)- and small unilamellar vesicles-NPs, already approved for use in humans. RESULTS: Both SAS-NPs and ORMOSIL-NPS presented a significant procoagulant activity. However, highly PEGylated ORMOSIL-NPs were particularly averse to the interaction with the soluble factors and cellular elements that may lead to intravascular blood coagulation. CONCLUSION: Stealth, highly PEGylated ORMOSIL-NPs with a poor procoagulant activity can be used as starting blocks to design hemocompatible nanomedical-devices.