Development and characterization of self-assembling nanoparticles using a bio-inspired amphipathic peptide for gene delivery

The design of a non-viral gene delivery vehicle capable of delivering and releasing a functional nucleic acid cargo intracellularly remains a formidable challenge. For systemic gene therapy to be successful a delivery vehicle is required that protects the nucleic acid cargo from enzymatic degradation, extravasates from the vasculature, traverses the cell membrane, disrupts the endosomal vesicles and unloads the cargo at its destination site, namely the nucleus for the purposes of gene delivery. This manuscript reports the extensive investigation of a novel amphipathic peptide composed of repeating RALA units capable of overcoming the biological barriers to gene delivery both in vitro and in vivo. Our data demonstrates the spontaneous self-assembly of cationic DNA-loaded nanoparticles when the peptide is complexed with pDNA. Nanoparticles were <100nm, were stable in the presence of serum and were fusogenic in nature, with increased peptide α-helicity at a lower pH. Nanoparticles proved to be non-cytotoxic, readily traversed the plasma membrane of both cancer and fibroblast cell lines and elicited reporter-gene expression following intravenous delivery in vivo. The results of this study indicate that RALA presents an exciting delivery platform for the systemic delivery of nucleic acid therapeutics.

Effects of zinc porphyrin and zinc phthalocyanine derivatives in photodynamic anticancer therapy under different partial pressures of oxygen in vitro

Photodynamic therapy (PDT) is gradually becoming an alternative method in the treatment of several diseases. Here, we investigated the role of oxygen in photodynamically treated cervical cancer cells (HeLa). The effect of PDT on HeLa cells was assessed by exposing cultured cells to disulphonated zinc phthalocyanine (ZnPcS₂) and tetrasulphonated zinc tetraphenylporphyrin (ZnTPPS₄). Fluorescence microscopy revealed their different localizations within the cells. ZnTPPS₄ seems to be mostly limited to the cytosol and lysosomes, whereas ZnPcS₂ is most likely predominantly attached to membrane structures, including plasmalemma and the mitochondrial membrane. Phototoxicity assays of PDT-treated cells carried out under different partial pressures of oxygen showed dose-dependent responses. Interestingly, ZnPcS₂ was also photodynamically effective at a minimal level of oxygen, under a nitrogen atmosphere. On the other hand, hyperbaric oxygenation did not lead to a higher PDT efficiency of either photosensitizer. Although both photosensitizers can induce a significant drop in mitochondrial membrane potential, ZnPcS₂ has a markedly higher effect on mitochondrial respiration that was completely blocked after two short light cycles. In conclusion, our observations suggest that PDT can be effective even in hypoxic conditions if a suitable sensitizer is chosen, such as ZnPcS₂, which can inhibit mitochondrial respiration.

Polyphenols from Silybum marianum inhibit in vitro the oxidant response of equine neutrophils and myeloperoxidase activity

A recent study showed that silymarin, a standardized extract of S. marianum might be used in the prevention of equine laminitis. We investigated the effects of quercetin and some compounds found in silymarin (silybin, taxifolin and dehydrosilybin) on reactive oxygen species (ROS) production and myeloperoxidase (MPO) release by stimulated equine neutrophils (PMNs) and on MPO activity. All compounds (tested between 100 nm and 100 μm) inhibited superoxide anion production by stimulated PMNs in a dose-dependent manner. Dehydrosilybin and quercetin inhibited superoxide production and MPO release from 10 μm. Classical MPO assay showed quercetin as the most potent inhibitor, followed by taxifolin, dehydrosilybin and silybin. SIEFED MPO assay highlighting the binding of tested compounds to MPO showed that only quercetin and taxifolin maintained an efficient inhibition above 90% at 10 μm. Altogether, our results showed a strong inhibition of PMN activation by planar compounds such as quercetin and dehydrosilybin and a strong inhibition of MPO activity by the smallest molecules, quercetin and taxifolin. In conclusion, the compounds from silymarin may be useful for modulating the oxidative response of PMNs, involved in the pathogenesis of laminitis, but further in vivo studies are needed.

In situ spectroscopic identification of the six types of asbestos

Exposure to asbestos fibres is related to a number of severe lung diseases, and therefore, rapid, accurate and reliable in situ or on-site asbestos detection in real-life samples is of considerable importance. This work presents a comprehensive investigation of all six types of asbestos by mid-infrared ATR-FTIR, NIR spectroscopy and Raman microspectroscopy. Our studies demonstrate that for practical applications, NIR spectroscopy is potentially the most powerful method for asbestos identification in materials utilised by the construction industry. By focusing on the narrow spectral region, 7300-7000 cm^-1 (~1370-1430 nm, overtones of O‒H vibrations), which is highly specific to these materials, and optimising the sensitivity and resolution of the instrumentation, we have been able to discriminate and identify each of the six types of asbestos with the level of detection significantly better than 1 wt%. Furthermore, straightforward computational analysis has allowed for automated objective evaluation of the spectroscopic data.

Silymarin Constituent 2,3-Dehydrosilybin Triggers Reserpine-Sensitive Positive Inotropic Effect in Perfused Rat Heart

2,3-dehydrosilybin (DHS) is a minor flavonolignan component of Silybum marianum seed extract known for its hepatoprotective activity. Recently we identified DHS as a potentially cardioprotective substance during hypoxia/reoxygenation in isolated neonatal rat cardiomyocytes. This is the first report of positive inotropic effect of DHS on perfused adult rat heart. When applied to perfused adult rat heart, DHS caused a dose-dependent inotropic effect resembling that of catecholamines. The effect was apparent with DHS concentration as low as 10 nM. Suspecting direct interaction with β-adrenergic receptors, we tested whether DHS can trigger β agonist-dependent gene transcription in a model cell line. While DHS alone was unable to trigger β agonist-dependent gene transcription, it enhanced the effect of isoproterenol, a known unspecific β agonist. Further tests confirmed that DHS could not induce cAMP accumulation in isolated neonatal rat cardiomyocytes even though high concentrations (≥ 10 μM) of DHS were capable of decreasing phosphodiesterase activity. Pre-treatment of rats with reserpine, an indole alkaloid which depletes catecholamines from peripheral sympathetic nerve endings, abolished the DHS inotropic effect in perfused hearts. Our data suggest that DHS causes the inotropic effect without acting as a β agonist. Hence we identify DHS as a novel inotropic agent.

Quercetin protects cardiomyoblasts against hypertonic cytotoxicity by abolishing intracellular Ca2+ elevations and mitochondrial depolarisation

BACKGROUND AND AIM

Osmotic changes represent a burden for the body and their limitation would be beneficial. We hypothesized that ubiquitous natural compounds could guard against cytotoxic effects of osmotic stress. We evaluated the anti-hypertonic mechanism of quercetin and 2,3-dehydrosilybin in H9c2 cells in vitro.

EXPERIMENTAL PROCEDURE

Protective effect of both compounds was determined by neutral red assay, cell apoptosis was estimated by measuring caspase-3 activity and verified by western blot and annexin V assay. Phosphorylation level of selected proteins was also detected. Mitochondrial membrane potential was evaluated using dye JC-1. Ca2+ signals were evaluated using genetically encoded fluorescent Ca2+ biosensor GCaMP7f. Formation of reactive oxygen species was measured using an oxidant-sensing probe dihydrofluorescein diacetate.

KEY RESULTS

Quercetin protected H9c2 cells against hypertonic stress-induced cell death. We observed a significant increase in intracellular Ca2+ levels ([Ca2+]cyto) when cells originally placed in a hypertonic solution were returned to a normotonic environment. Quercetin was found to prevent this increase in [Ca2+]cyto and also the depolarization of mitochondrial membrane potential.

CONCLUSIONS AND IMPLICATIONS

Quercetin, but not 2,3-dehydrosilybin, reduced adverse effects of osmotic stress mainly by dampening the elevation of [Ca2+]cyto and mitochondrial Ca2+ overload. This may consequently prevent MPTP pore opening and activation of apoptosis.