RESUMEN
PURPOSE: The aim of this study was to evaluate the ability of long-circulating PEGylated cyanoacrylate nanoparticles to diffuse into the brain tissue. METHODS: Biodistribution profiles and brain concentrations of [14C]-radiolabeled PEG-PHDCA, polysorbate 80 or poloxamine 908-coated PHDCA nanoparticles, and uncoated PHDCA nanoparticles were determined by radioactivity counting after intravenous administration in mice and rats. In addition, the integrity of the blood-brain barrier (BBB) after nanoparticles administration was evaluated by in vivo quantification of the diffusion of [14C]-sucrose into the brain. The location of fluorescent nanoparticles in the brain was also investigated by epi-fluorescent microscopy. RESULTS: Based on their long-circulating characteristics, PEGylated PHDCA nanoparticles penetrated into the brain to a larger extent than all the other tested formulations. Particles were localized in the ependymal cells of the choroid plexuses, in the epithelial cells of pia mater and ventricles, and to a lower extent in the capillary endothelial cells of BBB. These phenomena occurred without any modification of BBB permeability whereas polysorbate 80-coated nanoparticles owed, in part, their efficacy to BBB permeabilization induced by the surfactant. Poloxamine 908-coated nanoparticles failed to increase brain concentration probably because of their inability to interact with cells. CONCLUSIONS: This study proposes PEGylated poly (cyanoacrylate) nanoparticles as a new brain delivery system and highlights two requirements to design adequate delivery systems for such a purpose: a) long-circulating properties of the carrier, and b) appropriate surface characteristics to allow interactions with BBB endothelial cells.
Asunto(s)
Resinas Acrílicas/farmacocinética , Encéfalo/metabolismo , Polietilenglicoles/farmacocinética , Animales , Barrera Hematoencefálica , Fenómenos Químicos , Química Física , Difusión , Portadores de Fármacos , Sistemas de Liberación de Medicamentos , Colorantes Fluorescentes , Marcaje Isotópico , Masculino , Ratones , Microesferas , Tamaño de la Partícula , Permeabilidad/efectos de los fármacos , Ratas , Sacarosa/administración & dosificación , Sacarosa/farmacocinética , Tensoactivos/farmacología , Suspensiones , Distribución TisularRESUMEN
PEGylated polymeric nanoparticles are hereby presented as a potential efficient drug carrier for the delivery of active therapeutic molecules in prion experimental diseases. Based on their blood long-circulating characteristics, these PEGylated particles made by the amphiphilic copolymer poly [methoxy poly(ethylene glycol) cyanoacrylate-co-hexadecyl cyanoacrylate] (PEG-PHDCA), showed comparatively conventional non-PEGylated nanoparticles, a higher uptake by the spleen and the brain which are both the target tissues of PrPres accumulation in scrapie infected animals.
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Materiales Biocompatibles , Cianoacrilatos , Polietilenglicoles , Scrapie/tratamiento farmacológico , Animales , Materiales Biocompatibles/farmacocinética , Sangre/metabolismo , Encéfalo/metabolismo , Cianoacrilatos/farmacocinética , Portadores de Fármacos , Inyecciones Intravenosas , Masculino , Concentración Osmolar , Tamaño de la Partícula , Polietilenglicoles/farmacocinética , Ratas , Scrapie/fisiopatología , Distribución TisularRESUMEN
The involvement of spleen macrophages in the early stages of scrapie pathogenesis was studied by applying the 'macrophage-suicide technique' to scrapie-infected mice. This method comprises critically the intravenous administration to mice of dichloromethylene disphosphonate encapsulated into liposomes. Depletion of spleen macrophages before scrapie infection induced an increased amount of scrapie inoculum in the spleen, consequently leading to accelerated scrapie agent replication in the early phase of pathogenesis, as followed by PrPres accumulation, a specific hallmark of scrapie. The same effect was observed when spleen macrophages were depleted just before the beginning of scrapie agent replication. These findings suggest that macrophages may partly control scrapie infection in peripheral tissues by sequestration of the scrapie inoculum and may thus impair early scrapie agent replication in the spleen. In addition to macrophages, most follicular dendritic cells and B lymphocytes, which are thought to support scrapie agent replication, were also transiently depleted by dichloromethylene disphosphonate administration. This suggests that a compensatory mechanism is sufficient to ensure the persistence of infection in these early stages of pathogenesis.
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Macrófagos/inmunología , Scrapie/inmunología , Bazo/inmunología , Analgésicos no Narcóticos/farmacología , Animales , Linfocitos B/efectos de los fármacos , Linfocitos B/inmunología , Ácido Clodrónico/farmacología , Macrófagos/efectos de los fármacos , Ratones , Priones/metabolismo , Scrapie/virología , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunologíaRESUMEN
After intravenous injection, the main part of nanoparticles trapped by the spleen are concentrated in the marginal zone. The first step of this capture is the adhesion of the particles to the marginal zone macrophages. As classical techniques of cell suspension preparation did not allow to isolate without damage these actively capturing cells, tightly bound to a well-developed reticular meshwork, we designed a tissue slice incubation method, in order to study in vitro the interaction of nanoparticles with these particular macrophages, in conditions close to in vivo. In a serum supplemented medium, this in vitro model was able to give similar uptake profile than after intravenous injection of nanoparticles thus proving its validity. Surprisingly, no significant decrease of nanoparticles capture was observed when the medium was depleted from complement, immunoglobulins or proteins affine for heparin, while substitution of serum by purified albumin allowed a near optimal uptake. Addition of competitive ligands for lectin-like receptors did not show any clear inhibition of spleen capture. On the other hand, the scavenger receptor blocking agents, such as maleylated albumin or polyinosinic acid, induced a strong reduction of the spleen nanoparticles uptake. Thus, this paper proposes an in vitro binding assay as a reliable method to investigate the spleen capture of a large variety of nanoparticulate drug carriers. It is also a useful methodology to highlight the interactions between spleen cells and nanoparticles. The data obtained suggest that capture of nanoparticles depends on a multifactorial and complex phenomenon involving for a part albumin and the scavenger receptor.
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Proteínas Sanguíneas/metabolismo , Proteínas de la Membrana , Receptores de Lipoproteína , Bazo/citología , Bazo/metabolismo , Animales , Adhesión Celular , Medios de Cultivo , Macrófagos/fisiología , Ratones , Técnicas de Cultivo de Órganos , Tamaño de la Partícula , Poliestirenos , Receptores Inmunológicos/metabolismo , Receptores Depuradores , Receptores Depuradores de Clase B , Albúmina Sérica Bovina/metabolismoRESUMEN
PURPOSE: To investigate the influence of animal species and nanoparticle surface characteristics on the intrasplenic distribution of polystyrene nanoparticles. METHODS: Two types of fluorescent polystyrene nanoparticles (Estapor and Fluoresbrite), plain or coated, were used in mice and rats. First, a fluorimetric method was developed for nanoparticle tissue quantification. Then, intrasplenic distribution of plain or coated nanoparticles was studied using histological examination and image analysis. Finally, the role of direct interactions between nanoparticles and spleen capturing cells was assessed by in vitro binding assays, using incubation of thick spleen slices with polystyrene nanoparticles. RESULTS: The two types of polystyrene nanoparticles showed different levels of trapping: Fluoresbrite nanoparticles were more efficiently trapped by the spleen than Estapor nanoparticles, both in mice and rats. In mice, most of the injected nanoparticles were localized in the marginal zone of the spleen, involving a special population of capturing cells, while in rats, the predominant capture occured in the red pulp. In mice, coated nanoparticles were localized both in the marginal zone and in the red pulp, whereas the coating did not seem to change the intrasplenic distribution of the nanoparticles in rats. CONCLUSIONS: These complementary approaches showed different uptake pathways of nanoparticles, according to their surface characteristics and the rodent species used.
Asunto(s)
Bazo/metabolismo , Animales , Etilenodiaminas/farmacología , Fluorometría , Ratones , Microquímica , Tamaño de la Partícula , Poloxámero/farmacología , Polietilenglicoles/farmacología , Ratas , Solubilidad , Especificidad de la Especie , Propiedades de Superficie , Tensoactivos/farmacología , Agua/químicaRESUMEN
PURPOSE: To identify more accurately in the spleen, the areas and the cells where nanoparticulate carriers were taken up from the blood flow, a series of complementary approaches were used. METHODS: First, in and ex vivo examination of the whole spleen led to a global view of all the trapping areas. Then, histological studies on frozen sections of the same organ allowed for a more precise localization of these areas and image analysis gave an evaluation of tissue distribution of the nanoparticles. Finally, immunological and enzymological characteristics of the capturing cells were determined in situ, using monoclonal antibodies (F4/80 and anti-sialoadhesin) and cytochemical reactions (esterases and acid phosphatase). Furthermore incubation of spleen slices with different nanoparticles was used so as to know if the capture was due to a high capturing capacity of these cells or to a high blood flow in their vicinity. RESULTS: It was shown that more than 90% of the splenic capture was localized in the marginal zone of the follicles. The capturing cells form a special population of macrophages inserted in a reticular meshwork, showing low esterase and acid phosphatase activities, giving faint or no reaction with F4/80 or anti-sialoadhesin antibodies. The circulating nanoparticles were quickly trapped with rather low specificity by these cells. CONCLUSIONS: Combination of coherent approaches allowed for the tracking of capturing cells from in vivo observations to their in situ identification on immunological and enzymological criteria.
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Portadores de Fármacos/farmacocinética , Bazo/metabolismo , Animales , Femenino , Inmunohistoquímica , Ratones , Tamaño de la Partícula , Distribución TisularRESUMEN
The affinity of nanoparticles for hematopoietic organs could be valuable for the targeting of certain stimulating factors to those tissues, but this affinity should also be taken into account in the toxicological evaluation of those carriers, especially when they are loaded with antimitotic compounds such as doxorubicin. However, the cells responsible for the capture of the nanoparticles and their localization in these organs is an important point to know before trying to modulate the nanoparticle's tissue distribution. Thus, we have studied, in this paper, the capture, the localization, and the retention in the bone marrow and in the spleen of biodegradable poly(isohexyl cyanoacrylate) nanoparticles as well as of nonbiodegradable polystyrene nanoparticles. The histological localization of these nanoparticles has been completed by cytological localization with a method used in cytochemistry for the evaluation of intracellular accumulation of various substances, such as iron deposits in bone marrow sideroblasts. These data indicate that, in the bone marrow, after a quick passage through the endothelium, nanoparticles were dispersed throughout in the tissue and captured by all types of phagocytizing cells. In the spleen, nanoparticles were mainly localized in large angular capturing cells in the marginal zone of the lymphoid follicles.