The use of dopamine-hyaluronate associate-coated maghemite nanoparticles to label cells

Sodium hyaluronate (HA) was associated with dopamine (DPA) and introduced as a coating for maghemite (γ-Fe2O3) nanoparticles obtained by the coprecipitation of iron(II) and iron(III) chlorides and oxidation with sodium hypochlorite. The effects of the DPA anchorage of HA on the γ-Fe2O3 surface on the physicochemical properties of the resulting colloids were investigated. Nanoparticles coated at three different DPA-HA/γ-Fe2O3 and DPA/HA ratios were chosen for experiments with rat bone marrow mesenchymal stem cells and human chondrocytes. The nanoparticles were internalized into rat bone marrow mesenchymal stem cells via endocytosis as confirmed by Prussian Blue staining. The efficiency of mesenchymal stem cell labeling was analyzed. From among the investigated samples, efficient cell labeling was achieved by using DPA-HA-γ-Fe2O3 nanoparticles with DPA-HA/γ-Fe2O3 = 0.45 (weight/ weight) and DPA/HA = 0.038 (weight/weight) ratios. The particles were used as a contrast agent in magnetic resonance imaging for the labeling and visualization of cells

Optimalizace a vyuziti MR spektroskopickych a zobrazovacich metod

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Human conditionally immortalized neural stem cells improve locomotor function after spinal cord injury in the rat

INTRODUCTION: A growing number of studies have highlighted the potential of stem cell and more-differentiated neural cell transplantation as intriguing therapeutic approaches for neural repair after spinal cord injury (SCI). METHODS: A conditionally immortalized neural stem cell line derived from human fetal spinal cord tissue (SPC-01) was used to treat a balloon-induced SCI. SPC-01 cells were implanted into the lesion 1 week after SCI. To determine the feasibility of tracking transplanted stem cells, a portion of the SPC-01 cells was labeled with poly-L-lysine-coated superparamagnetic iron-oxide nanoparticles, and the animals grafted with labeled cells underwent magnetic resonance imaging. Functional recovery was evaluated by using the BBB and plantar tests, and lesion morphology, endogenous axonal sprouting and graft survival, and differentiation were analyzed. Quantitative polymerase chain reaction (qPCR) was used to evaluate the effect of transplanted SPC-01 cells on endogenous regenerative processes. RESULTS: Transplanted animals displayed significant motor and sensory improvement 2 months after SCI, when the cells robustly survived in the lesion and partially filled the lesion cavity. qPCR revealed the increased expression of rat and human neurotrophin and motor neuron genes. The grafted cells were immunohistologically positive for glial fibrillary acidic protein (GFAP); however, we found 25% of the cells to be positive for Nkx6.1, an early motor neuron marker. Spared white matter and the robust sprouting of growth-associated protein 43 (GAP43)(+) axons were found in the host tissue. Four months after SCI, the grafted cells matured into Islet2(+) and choline acetyltransferase (ChAT)(+) neurons, and the graft was grown through with endogenous neurons. Grafted cells labeled with poly-L-lysine-coated superparamagnetic nanoparticles before transplantation were detected in the lesion on T(2)-weighted images as hypointense spots that correlated with histologic staining for iron and the human mitochondrial marker MTCO2. CONCLUSIONS: The transplantation of SPC-01 cells produced significant early functional improvement after SCI, suggesting an early neurotrophic action associated with long-term restoration of the host tissue, making the cells a promising candidate for future cell therapy in patients with SCI

Magnetické nanočástice Ga-substituovaného epsilon-Fe2O3 pro biomedicínské aplikace: Magnetické vlastnosti, transverzální relaxivita a účinky částic obalených oxidem křemičitým na cytoskelet

Magnetic nanoparticles of epsilon-Fe1.76Ga0.24O3 with the volume-weighted mean size of 17 nm were prepared by thermal treatment of a mesoporous silica template impregnated with metal nitrates and were coated with silica shell of four different thicknesses in the range 6-24 nm. The bare particles exhibited higher magnetization than the undoped compound, 22.4 Am-2 kg(-1) at 300 K, and were characterized by blocked state with the coercivity of 1.2 T at 300 K, being thus the very opposite of superparamagnetic iron oxides. The relaxometric study of the silica-coated samples at 0.47 T revealed promising properties for MRI, specifically, transverse relaxivity of 89-168 s(-1) mmol(f.u.)(-1) L depending on the shell thickness was observed. We investigated the effects of the silica-coated nanoparticles on human A549 and MCF-7 cells. Cell viability, proliferation, cell cycle distribution, and the arrangement of actin cytoskeleton were assessed, as well as formation and maturation of focal adhesions. Our study revealed that high concentrations of silica-coated particles with larger shell thicknesses of 16-24 nm interfere with the actin cytoskeletal networks, inducing thus morphological changes. Consequently, the focal adhesion areas were significantly decreased, resulting in impaired cell adhesion.Magnetické nanočástice epsilon-Fe1.76Ga0.24O3 o průměrné velikostí 17 nm byly připraveny tepelným zpracováním mezoporézního oxidu křemičitého impregnovaného dusičnany kovu a byly potaženy vrstvou siliky čtyř různých tloušťek v rozmezí 6-24 nm. Holé částice vykazovaly vyšší magnetizaci než nedopovaná sloučenina, 22,4 Am-2 kg (-1) při 300 K, a byly charakterizovány blokovaným stavem s koercivitou 1,2 T při 300 K, což je pravý opak superparamagnetických oxidů železa. Relaxometrická studie vzorků potažených silikou při 0,47 T odhalila slibné vlastnosti pro MRI, konkrétně byla pozorována transverzální relaxivita 89-168 s (-1) mmol (f.u.) (- 1) L v závislosti na tloušťce obalu. Zkoumali jsme účinky nanočástic potažených silikou na lidské buňky A549 a MCF-7. Byla hodnocena viabilita buněk, proliferace, buněčný cyklus a uspořádání aktinového cytoskeletu, stejně jako tvorba a zrání fokálních adhezí. Naše studie odhalila, že vysoké koncentrace částic potažených silikou o větší tloušťce 16-24 nm interferují s aktinovým cytoskeletem a vyvolávají tak morfologické změny. V důsledku toho byla významně zmenšena plocha fokálních adhezí, což mělo za následek narušení buněčné adheze

Multiparametric quantitative brain MRI in neurological and hepatic forms of Wilson's disease

Background: In Wilson's disease (WD), demyelination, rarefaction, gliosis, and iron accumulation in the deep gray matter cause opposing effects on T-weighted MR signal. However, the degree and interplay of these changes in chronically treated WD patients has not been quantitatively studied. Purpose: To compare differences in brain multiparametric mapping between controls and chronically treated WD patients with neurological (neuro-WD) and hepatic (hep-WD) forms to infer the nature of residual WD neuropathology. Study Type: Cross-sectional. Population/Subjects: Thirty-eight WD patients (28 neuro-WD, 10 hep-WD); 26 healthy controls. Field Strength/Sequence: 3.0T: susceptibility, T*, T, T relaxometry; 1.5T: T, T relaxometry. Assessment: The following 3D regions of interest (ROIs) were manually segmented: globus pallidus, putamen, caudate nucleus, and thalamus. Mean bulk magnetic susceptibility, T*, T, and T relaxation times were calculated for each ROI. Statistical Tests: The effect of group (neuro-WD, hep-WD, controls) and age was assessed using a generalized least squares model with different variance for each ROI and quantitative parameter. A general linear hypothesis test with Tukey adjustment was used for post-hoc between-group analysis; P < 0.05 was considered significant. Results: Susceptibility values were higher in all ROIs in neuro-WD compared to controls and hep-WD (P < 0.001). In basal ganglia, lower T and T* were found in neuro-WD compared to controls (P < 0.01) and hep-WD (P < 0.05) at 3.0T. Much smaller intergroup differences for T in basal ganglia were observed at 1.5T compared to 3.0T. In the thalamus, increased susceptibility in neuro-WD was accompanied by increased T at both field strengths (P < 0.001 to both groups), and an increased T at 1.5T only (P < 0.001 to both groups). Data Conclusion: We observed significant residual brain MRI abnormalities in neuro-WD but not in hep-WD patients on chronic anticopper treatment. Patterns of changes were suggestive of iron accumulation in the basal ganglia and demyelination in the thalamus; 3.0T was more sensitive for detection of the former and 1.5T of the latter abnormality. Level of Evidence: 2. Technical Efficacy Stage: 3. J. Magn. Reson. Imaging 2019

Využití feromagnetických nanočástic s nízkou Curieovou teplotou pro zobrazovací magnetickou rezonancí řízenou termoablaci

Magnetic nanoparticles represent a tool for use in magnetic resonance imaging (MRI)-guided thermoablation of tumors using an external high-frequency mag¬netic field. To avoid local overheating, perovskite nanoparticles with a lower Curie temperature (Tc) were proposed for use in thermotherapy. However, deposited power decreases when approaching the Curie temperature and consequently may not be sufficient for effective ablation. The goal of the study was to test this hypothesis. Perovskite nanoparticles (Tc = 66–74°C) were characterized and tested both in vitro and in vivo. Magnetic particles with low Tc can be tracked in vivo by MRI and heated by a HF field. The particles are capable of inducing cell apoptosis in suspensions in vitro at high concentrations only.Magnetické nanočástice představují nástroj pro použití v magnetickou rezonancí (MRI) řízené termoablaci nádorů pomocí externího vysokofrekvenčního magnetického pole. Aby se zabránilo lokálnímu přehřátí, byly navrženy perovskitové nanočástice s nižší Curieovou teplotou (Tc) pro použití v termoterapii. Nicméně vložená energie se snižuje, když se blíží Curieova teplota a v důsledku toho nemusí být dostatečná pro účinnou ablaci. Cílem této studie bylo otestovat tuto hypotézu. Perovskitové nanočástice (Tc = 66–74 °C) byly charakterizovány a testovány jak in vitro, tak in vivo. Magnetické částice s nízkou Tc mohou být sledovány in vivo pomocí MRI a zahřívány VF polem. Tyto částice jsou schopné indukovat apoptózu buněk v suspenzi in vitro při pouze vysokých koncentracích

Mn-Zn feritové nanočástice obalené silikou a titanem: syntéza, transverzální relaxivita a cytotoxicita

Mn-Zn ferrite nanoparticles of composition Mn0.61Zn0.42Fe1.97O4 and mean size of crystallites d(XRD) = 11 nm are synthesized under hydrothermal conditions as a single-phase product. Subsequently, two coated samples are prepared by encapsulation of the ferrite particles into silica and titania. Transmission electron microscopy confirms the core-shell structure of the products and shows that the cores are actually formed by small clusters of ferrite crystallites. Powder X-ray diffraction, combined with experimental hydrothermal treatment of the titania-coated product, demonstrates that the titania coating is amorphous but can easily be transformed into anatase. The colloidal stability of nanoparticles in water is evidenced by dynamic light scattering, and the respective hydrodynamic sizes are d(Z) = 87 and 157 nm for the silica-coated and titania-coated particles. The colloidal behavior is confirmed based on the measurements of zeta potential, whose negative values lead to strong Coulombic repulsion among coated particles. Magnetic measurements on bare and coated particles show high magnetization of Mn0.61Zn0.42Fe1.97O4 cores and superparamagnetic state at room temperature. The relaxometric study on aqueous suspensions in magnetic fields of 0.5 and 11.75 T reveals high transverse relaxivity of the samples and two distinct forms of its temperature dependence, which are analyzed with respect to the role of temperature-dependent parameters, that is, the diffusion of water and the magnetization of ferrite cores. Finally, careful evaluation of cytotoxicity of coated particles is carried out by using two different methods, namely, the determination of viability and proliferation of Jurkat cells and the real-time monitoring of attachment and proliferation of A549 cells. In the studied range of concentrations, the viability and proliferation of suspension cells are not affected, and only negligible effects are detected in the cell index of adherent cells.Mn-Zn feritové nanočástice o složení Mn0.61Zn0.42Fe1.97O4 a průměrné velikosti krystalů d(XRD) = 11 nm) byly připraveny hydrotermální syntézou. Nakonec byla podrobně vyhodnocena cytotoxicita obalených nanočástic pomocí dvou odlišných metod: pomocí stanovení viability a proliferace buněčné linie Jurkat a pomocí analýzy adheze a proliferace buněčné linie A549 v reálném čase. V rámci hodnoceného koncentračního rozsahu, nebyla ovlivněna viabilita a proliferace suspenzních buněk a pouze zanedbatelný vliv na buněčný index byl pozorován u adherentních buněk

Multimodální kontrastní látky umožňující snímání pH na podkladě organickými molekulami funkcionalizovaných zlatých nanoslupek s manganato-zinečnato feritovým jádrem

Highly complex nanoparticles combining multimodal imaging with the sensing of physical properties in biological systems can considerably enhance biomedical research, but reports demonstrating the performance of a single nanosized probe in several imaging modalities and its sensing potential at the same time are rather scarce. Gold nanoshells with magnetic cores and complex organic functionalization may offer an efficient multimodal platform for magnetic resonance imaging (MRI), photoacoustic imaging (PAI), and fluorescence techniques combined with pH sensing by means of surface-enhanced Raman spectroscopy (SERS). In the present study, the synthesis of gold nanoshells with Mn-Zn ferrite cores is described, and their structure, composition, and fundamental properties are analyzed by powder X-ray diffraction, X-ray fluorescence spectroscopy, transmission electron microscopy, magnetic measurements, and UV-Vis spectroscopy. The gold surface is functionalized with four different model molecules, namely thioglycerol, meso-2,3-dimercaptosuccinate, 11-mercaptoundecanoate, and (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, to analyze the effect of varying charge and surface chemistry on cells in vitro. After characterization by dynamic and electrophoretic light scattering measurements, it is found that the particles do not exhibit significant cytotoxic effects, irrespective of the surface functionalization. Finally, the gold nanoshells are functionalized with a combination of 4-mercaptobenzoic acid and 7-mercapto-4-methylcoumarin, which introduces a SERS active pH sensor and a covalently attached fluorescent tag at the same time. H-1 NMR relaxometry, fluorescence spectroscopy, and PAI demonstrate the multimodal potential of the suggested probe, including extraordinarily high transverse relaxivity, while the SERS study evidences a pH-dependent spectral response.Vysoce komplexní nanočástice kombinující multimodální zobrazování se snímáním fyzikálních vlastností v biologických systémech mohou výrazně zlepšit biomedicínský výzkum. Zlaté nanoslupky s magnetickými jádry a komplexní organickou funkcionalizací mohou nabídnout účinnou multimodální platformu pro zobrazování magnetickou rezonancí (MRI), fotoakustické zobrazování (PAI) a fluorescenční techniky kombinované se snímáním pH pomocí povrchově zesílené Ramanovy spektroskopie (SERS). V této studii je popsána syntéza zlatých nanoslupek s Mn-Zn feritovými jádry, a také jejich struktura, složení a základní vlastnosti. Zlatý povrch byl funkcionalizován čtyřmi různými modelovými molekulami, jmenovitě thioglycerolem, meso-2,3-dimerkaptosukcinátem, 11-merkaptoundekanoátem a (11-merkaptoundecyl)-N,N,N-trimethylamoniumbromidem. Bylo zjištěno, že částice nevykazují významné cytotoxické účinky, bez ohledu na funkcionalizaci povrchu. Nakonec byly zlaté nanoslupky funkcionalizovány kombinací kyseliny 4-merkaptobenzoové a 7-merkapto-4-methylkumarinu. NMR relaxometrie, fluorescenční spektroskopie a PAI demonstrují multimodální potenciál navrhované sondy, včetně mimořádně vysoké příčné relaxivity, zatímco studie SERS potvrzuje spektrální odezvu závislou na pH