Interaction of differently functionalized fluorescent silica nanoparticles with neural stem- and tissue-type cells.

Abstract Engineered amorphous silica nanoparticles (SiO2 NPs), due to simple and low cost production, are increasingly used in commercial products and produced on an industrial scale. Despite the potential benefits, there is a concern that exposure to certain types of SiO2 NPs may lead to adverse health effects. As some NPs can cross the blood--brain barrier and may, in addition, reach the central nervous system through the nasal epithelium, this study addresses the responses of different neural tissue-type cells including neural stem cells, neurons, astrocytes and microglia cells to increasing doses of 50 nm fluorescent core/shell SiO2 NPs with different [-NH2, -SH and polyvinylpyrrolidone (PVP)] surface chemistry. The SiO2 NPs are characterized using a variety of physicochemical methods. Assays of cytotoxicity and cellular metabolism indicates that SiO2 NPs cause cell death only at high particle doses, except PVP-coated SiO2 NPs which do not harm cells even at very high concentrations. All SiO2 NPs, except those coated with PVP, form large agglomerates in physiological solutions and adsorb a variety of proteins. Except PVP-NPs, all SiO2 NPs adhere strongly to cell surfaces, but internalization differs depending on neural cell type. Neural stem cells and astrocytes internalize plain SiO2, SiO2-NH2 and SiO2-SH NPs, while neurons do not take up any NPs. The data indicates that the PVP coat, by lowering the particle-biomolecular component interactions, reduces the biological effects of SiO2 NPs on the investigated neural cells

Lack of neuroprotection in the absence of P2X7 receptors in toxin-induced animal models of Parkinson's disease

<p>Abstract</p> <p>Background</p> <p>Previous studies indicate a role of P2X₇receptors in processes that lead to neuronal death. The main objective of our study was to examine whether genetic deletion or pharmacological blockade of P2X₇receptors influenced dopaminergic cell death in various models of Parkinson's disease (PD).</p> <p>Results</p> <p>mRNA encoding P2X₇and P2X₄receptors was up-regulated after treatment of PC12 cells with 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP). P2X₇antagonists protected against MPTP and rotenone induced toxicity in the LDH assay, but failed to protect after rotenone treatment in the MTT assay in PC12 cells and in primary midbrain culture. <it>In vivo </it>MPTP and <it>in vitro </it>rotenone pretreatments increased the mRNA expression of P2X₇receptors in the striatum and substantia nigra of wild-type mice. Basal mRNA expression of P2X₄receptors was higher in P2X₇knockout mice and was further up-regulated by MPTP treatment. Genetic deletion or pharmacological inhibition of P2X₇receptors did not change survival rate or depletion of striatal endogenous dopamine (DA) content after <it>in vivo </it>MPTP or <it>in vitro </it>rotenone treatment. However, depletion of norepinephrine was significant after MPTP treatment only in P2X₇knockout mice. The basal ATP content was higher in the substantia nigra of wild-type mice, but the ADP level was lower. Rotenone treatment elicited a similar reduction in ATP content in the substantia nigra of both genotypes, whereas reduction of ATP was more pronounced after rotenone treatment in striatal slices of P2X₇deficient mice. Although the endogenous amino acid content remained unchanged, the level of the endocannabinoid, 2-AG, was elevated by rotenone in the striatum of wild-type mice, an effect that was absent in mice deficient in P2X₇receptors.</p> <p>Conclusions</p> <p>We conclude that P2X₇receptor deficiency or inhibition does not support the survival of dopaminergic neurons in an <it>in vivo </it>or <it>in vitro </it>models of PD.</p

Antitumor Effects of a New Retinoate of the Fungal Cytotoxin Illudin M in Brain Tumor Models

While the fungal metabolite illudin M (1) is indiscriminately cytotoxic in cancer and non-malignant cells, its retinoate 2 showed a greater selectivity for the former, especially in a cerebral context. Illudin M killed malignant glioma cells as well as primary neurons and astrocytes at similarly low concentrations and destroyed their microtubule and glial fibrillary acidic protein (GFAP) networks. In contrast, the ester 2 was distinctly more cytotoxic in highly dedifferentiated U87 glioma cells than in neurons, which were even stimulated to enhanced growth. This was also observed in co-cultures of neurons with U87 cells where conjugate 2 eventually killed them by induction of differentiation based on the activation of nuclear receptors, which bind to retinoid-responsive elements (RARE). Hence, illudin M retinoate 2 appears to be a promising drug candidate

Detection of cation migration through gramicidin channels in membrane-sandwich sensor set-ups.

<p>Refractive indices (n_cTM) of the sensor-covering fluid layer were measured in the transverse magnetic (TM) mode in sensor set-ups containing empty or lipid-filled filter membranes (<b>A</b>, <b>B</b>) after injecting ethanolamine (<b>A</b>) or guanidine (<b>B</b>) solutions, and after the incorporation of gramicidin (<b>C</b>, <b>D</b>). The inserts show averages and standard deviations of n_cTM changes, calculated from three independent experiments. Significant (***p<0.001; paired <i>t</i>-test) differences were found in response to filling with liposomes regardless of the chemical nature of the analyte (<b>A</b>, <b>B</b>). Incorporation of gramicidin, while resulted in enhanced permeation of ethanolamine (<b>C</b>), did not cause detectable changes in the move of guanidine (<b>D</b>).</p

Schematic view of the membrane-sandwich sensor set-up.

<p>A thick (140 µm) PTFE lipid-holder membrane was placed on the top of a thin (23 µm) PET membrane for complete separation of lipid material from the sensor surface.</p

Demonstration of Cl^–-channel functions of cell-derived GABA receptors in the membrane-sandwich sensor set-up.

<p>OWLS recordings were made in Cl^–-free ACSF as running buffer with injection of Cl^–-containing ACSF (ACSF) with or without GABA and the channel blocker bicuculline (ACSF+GABA and ACSF+GABA+Bic, respectively). (<b>A</b>) Changes of the effective refractive index (NTM) values in a representative OWLS assay. (<b>B</b>) Changes in the refractive index (n_cTM) in response to the GABA-channel blocker bicuculline are shown from a representative experiment. (<b>C</b>) Summary of refractive index (nc_TM) changes (Δnc_TM) in response to transfusion with Cl^–-containing buffer (ACSF), in the presence of the agonist GABA (ACSF+GABA) or in the presence of both GABA and the channel-blocker bicucullin (ACSF+GABA+bicucullin). Δnc_TM values were calculated from data of 4 independent series of experiments (n≥4); averages and standard deviations are presented.</p

OWLS recordings of deposition of multiple liposome layers and permeability for small organic cations.

<p>(<b>A</b>) Biotinylated sensors were treated with (1) NeutrAvidin; (2) biotin-ssDNA; (3) Chol-dsDNA1-tagged liposomes; (4) Chol-dsDNA2. The insert shows the increasing thickness (dA) of the deposited material on the surface reaching the detectable maximum (∼200 nm) after the second injection of liposomes. (<b>B</b>, <b>C</b>) Changes of the effective refractive indices (NTM) in a representative series of experiments with cross-linked multilayer of liposomes without (<b>B</b>) or with (<b>C</b>) gramicidin channels after injections of ethanolamine (5), methylamine (6) or guanidine (7) solutions.</p

The minimum amount of detectable material in assays with various sensor set-ups.

<p>The minimum amount of detectable material in assays with various sensor set-ups.</p