Magnetic nanoparticles in primary neural cell cultures are mainly taken up by microglia

<p>Abstract</p> <p>Background</p> <p>Magnetic nanoparticles (MNPs) offer a large range of applications in life sciences. Applications in neurosciences are one focus of interest. Unfortunately, not all groups have access to nanoparticles or the possibility to develop and produce them for their applications. Hence, they have to focus on commercially available particles. Little is known about the uptake of nanoparticles in primary cells. Previously studies mostly reported cellular uptake in cell lines. Here we present a systematic study on the uptake of magnetic nanoparticles (MNPs) by primary cells of the nervous system.</p> <p>Results</p> <p>We assessed the internalization in different cell types with confocal and electron microscopy. The analysis confirmed the uptake of MNPs in the cells, probably with endocytotic mechanisms. Furthermore, we compared the uptake in PC12 cells, a rat pheochromocytoma cell line, which is often used as a neuronal cell model, with primary neuronal cells. It was found that the percentage of PC12 cells loaded with MNPs was significantly higher than for neurons. Uptake studies in primary mixed neuronal/glial cultures revealed predominant uptake of MNPs by microglia and an increase in their number. The number of astroglia and oligodendroglia which incorporated MNPs was lower and stable. Primary mixed Schwann cell/fibroblast cultures showed similar MNP uptake of both cell types, but the Schwann cell number decreased after MNP incubation. Organotypic co-cultures of spinal cord slices and peripheral nerve grafts resembled the results of the dispersed primary cell cultures.</p> <p>Conclusions</p> <p>The commercial MNPs used activated microglial phagocytosis in both disperse and organotypic culture systems. It can be assumed that <it>in vivo </it>application would induce immune system reactivity, too. Because of this, their usefulness for <it>in vivo </it>neuroscientific implementations can be questioned. Future studies will need to overcome this issue with the use of cell-specific targeting strategies. Additionally, we found that PC12 cells took up significantly more MNPs than primary neurons. This difference indicates that PC12 cells are not a suitable model for natural neuronal uptake of nanoparticles and qualify previous results in PC12 cells.</p

Synthesis and characterization of nanoparticles of MFe2O4 (M=Fe, CO, Ni) for application in magnetic hyperthermia

Las nanopartículas magnéticas de óxido de hierro constituyen en la actualidad uno de los sistemas más prometedores dentro del campo de la biomedicina. Debido a las novedosas propiedades que presentan, su estudio se ha convertido en una actividad muy importante en la investigación de materiales magnéticos con carácter aplicativo. Por lo tanto, la motivación fundamental para la síntesis y estudio de coloides biocompatibles es el estudio de las propiedades magnéticas derivadas de las dimensiones nanométricas y la relación área superficial contra volumen existente. En el presente trabajo se ha estudiado la preparación de suspensiones coloidales de partículas de magnetita y ferritas de cobalto y níquel para aplicaciones biomédicas, abarcando tanto su síntesis como la caracterización de las propiedades. Para llevar a cabo la síntesis de las partículas se ha estudiado un método muy novedoso como es el de la descomposición térmica de precursores orgánicos de hierro en disolventes orgánicos y en presencia de surfactantes. Este método conduce a nanopartículas magnéticas monodispersas y muy cristalinas cuyo tamaño medio, forma y distribución pueden variar en función de parámetros experimentales como la naturaleza y concentración de los reactivos, además del control de la rampa de temperatura. Las propiedades estructurales de estas partículas son mejores que las obtenidas por métodos más convencionales como la coprecipitación o la pirolisis láser. Dado el carácter hidrófobo de las partículas sintetizadas, éstas no son aptas para su uso en biomedicina por lo que se ha estudiado la transferencia al medio acuoso, consiguiendo obtener suspensiones estables en agua menores de 100 nm. Las nanopartículas obtenidas se evaluaron in vitro como agentes de calentamiento para hipertermia magnética mediante la Absorción Específica de Potencia (SPA). Los valores obtenidos dependen tanto del tamaño de partícula como de la distribución de tamaños. El objetivo global está orientado al desarrollo de una nueva terapia de hipertermia magnética con aplicación en oncología

Long-term stability and reproducibility of magnetic colloids are key issues for steady values of specific power absorption over time

Virtually all clinical applications of magnetic nanoparticles (MNPs) require the formulation of biocompatible, water-based magnetic colloids. For magnetic hyperthermia, the requirements also include a high colloidal stability against precipitation and agglomeration of the constituent MNPs to maintain the heating efficiency of the ferrofluid in the long term. Agglomeration can change the heating efficiency by forming MNP clusters that modify the magnetic dipolar interactions between particles. Additionally, precipitation of the MNPs (i.e., the heating sources within the liquid) can change the measured heating rates of a colloid by altering the heat flow dynamics as the particles plunge to the precipitate. The specific power absorption (SPA) of single-domain MNPs depends critically on the average particle size and size distribution width and therefore first-rate reproducibility of different batches with respect to these parameters is also needed. We have studied the evolution of the SPA of highly reproducible and stable water-based colloids composed of polymer-coated Fe3O4 magnetic nanoparticles. By measuring the specific power absorption (SPA) values for 1 year as a function of field amplitude and frequency (H = 24 kA/m; 260 = f = 830 kHz), we have demonstrated that the SPA values of these samples can be reproduced in successive synthetic batches and stable for several months due to the in situ polymer coating that provides colloidal stability and keeps dipolar interactions negligible

The Chromenopyrazole Scaffold in the Modulation of the Endocannabinoid System: A Broad Therapeutic Prospect

The endogenous cannabinoid system (ECS) has been recognized as one of the most important neuromodulatory systems. This system plays a crucial role in the regulation of numerous pathophysiological conditions such as pain, cancer, or neurodegeneration. Despite the vast effort focused on the development of drugs targeting the ECS, thus far, the clinical use of synthetic and phytogenic cannabinoids has been limited to pain, emesis and appetite due to their undesirable psychoactive properties. Therefore, novel strategies to therapeutically exploit the cannabinoids need to be developed to overcome these side-effects. Moreover, novel chemical tools to study the role of possible additional cannabinoid missing receptors, such as GPR55, need to be addressed to fully unravel the pharmacology of this complex system.In this scenario, the chromenopyrazole scaffold was recently discovered as a privileged structure in drug discovery targeting the ECS. In this review, the development of novel modulators of the ECS based on the chromenopyrazole scaffold will be thoroughly discussed. Pharmacological avenues for this novel chemotype, as well as future perspectives will be analyzed

Derivados de cromenopirazoles como ligandos de receptores de cannabinoides

Derivados de cromenopirazoles como ligandos de receptores de cannabinoides. Compuestos derivados de cromenopirazoles que son ligandos de receptores de cannabinoides, su uso para la fabricación de un medicamento, uso de este medicamento para el tratamiento y/o la prevención de trastornos asociados a los receptores de cannabinoides, uso de dicho compuesto como reactivo en ensayos biológicos relacionados con receptores de cannabinoides y procedimiento de obtención de los mismos.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad Complutense de MadridA1 Solicitud de patente con informe sobre el estado de la técnic

Magnetic field-assisted gene delivery: achievements and therapeutic potential

The discovery in the early 2000’s that magnetic nanoparticles (MNPs) complexed to nonviral or viral vectors can, in the presence of an external magnetic field, greatly enhance gene transfer into cells has raised much interest. This technique, called magnetofection, was initially developed mainly to improve gene transfer in cell cultures, a simpler and more easily controllable scenario than in vivo models. These studies provided evidence for some unique capabilities of magnetofection. Progressively, the interest in magnetofection expanded to its application in animal models and led to the association of this technique with another technology, magnetic drug targeting (MDT). This combination offers the possibility to develop more efficient and less invasive gene therapy strategies for a number of major pathologies like cancer, neurodegeneration and myocardial infarction. The goal of MDT is to concentrate MNPs functionalized with therapeutic drugs, in target areas of the body by means of properly focused external magnetic fields. The availability of stable, nontoxic MNP-gene vector complexes now offers the opportunity to develop magnetic gene targeting (MGT), a variant of MDT in which the gene coding for a therapeutic molecule, rather than the molecule itself, is delivered to a therapeutic target area in the body. This article will first outline the principle of magnetofection, subsequently describing the properties of the magnetic fields and MNPs used in this technique. Next, it will review the results achieved by magnetofection in cell cultures. Last, the potential of MGT for implementing minimally invasive gene therapy will be discussed.Instituto de Investigaciones Bioquímicas de La Plat

Obesity and the endocannabinoid system: Is there still a future for CB1 antagonists in obesity?

The current epidemic of obesity in western countries is being worsened by the lack of effective pharmacotherapies. The apparent success of a central nervous systemacting cannabinoid CB1 receptor antagonist-based treatment for obesity was hampered by the appearance of psychiatric side effects in certain patients. These adverse effects forced its withdrawal from the market. However, the discovery that the main beneficial metabolic effects of cannabinoid CB1 receptor antagonists were derived of its activity in peripheral tissues, including the adipose tissue, opened the possibility of rescuing this type of therapy. This goal might be achieved by differential medicinal chemistry approaches. The present review examines these options that include peripheral-restricted cannabinoid CB1 receptor antagonists, dual ligands and combinatorial therapies using sub-effective doses of CB1 receptor antagonists that might be devoid of side effects.Peer Reviewe

Utilización de campos magnéticos y nanopartículas magnéticas para la orientación de células neuronales

Este Trabajo Fin de Grado se centra en el estudio de la capacidad de nanopartículas de magnetita (MNPs) biocompatibles de orientar células cuando éstas las ingieren y son sometidas a un campo magnético estático. Se pretende desarrollar una configuración de campo que optimice la fuerza magnética que actúa sobre estas MNPs absorbidas. El papel de la fuerza es orientar los organismos celulares. Por tratarse de componentes del tejido nervioso, las células empleadas poseen unas ramificaciones cortas e irregulares en el cuerpo celular, en cuya observación nos centraremos para hablar de esa orientación. Tras un estudio teórico previo de los parámetros a optimizar de la fuerza, se simulará el campo magnético mediante un algoritmo de elementos finitos (FEMM). Este método proporcionará resultados numéricos de los diseños de perfiles magnéticos realizados, que servirán como modelo para la construcción de un aplicador de imanes de NdFeB. Se busca reproducir en el laboratorio del INA los valores simulados y terminar haciendo un análisis estadístico del ángulo de la orientación de las células neuronales con el campo magnético, para concluir que tal orientación existe

Generation of magnetized olfactory ensheathing cells for regenerative studies in the central and peripheral nervous tissue

As olfactory receptor axons grow from the peripheral to the central nervous system (CNS) aided by olfactory ensheathing cells (OECs), the transplantation of OECs has been suggested as a plausible therapy for spinal cord lesions. The problem with this hypothesis is that OECs do not represent a single homogeneous entity, but, instead, a functionally heterogeneous population that exhibits a variety of responses, including adhesion and repulsion during cell-matrix interactions. Some studies report that the migratory properties of OECs are compromised by inhibitory molecules and potentiated by chemical gradients. In this paper, we report a system based on modified OECs carrying magnetic nanoparticles as a proof of concept experiment enabling specific studies aimed at exploring the potential of OECs in the treatment of spinal cord injuries. Our studies have confirmed that magnetized OECs (i) survive well without exhibiting stress-associated cellular responses; (ii) in vitro, their migration can be modulated by magnetic fields; and (iii) their transplantation in organotypic slices of spinal cord and peripheral nerve showed positive integration in the model. Altogether, these findings indicate the therapeutic potential of magnetized OECs for CNS injuries

Ex situ integration of iron oxide nanoparticles onto exfoliated expanded graphite flakes in aqueous suspension

Hybrid structures composed of exfoliated expanded graphite (EG) and iron oxide nanocrystals were produced by an ex situ process. The iron oxide nanoparticles coated with meso-2,3-dimercaptosuccinic acid (DMSA), or poly(acrylic acid) (PAA) were integrated onto the exfoliated EG flakes by mixing their aqueous suspensions at room temperature under the support of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinnimide (NHS). EG flakes both naked and functionalized with branched polyethylenimine (PEI) were employed. Complete integration of the two constituents was achieved and stability was maintained for more than 12 months. No preferential spatial distribution of anchoring sites for attachment of iron oxide nanoparticles was observed, regardless of whether the EG flakes were used naked or functionalized with PEI molecules. The structural and physicochemical characteristics of the exfoliated expanded graphite and its hybrid nano-structures were investigated by SEM, TEM, FTIR and Raman techniques