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Hazard effects of nanoparticles in central nervous system: Searching for biocompatible nanomaterials for drug delivery

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... Nevertheless, targeted therapy particularly involving metallic NPs have been shown to cause neurological toxicity leading to tissue damage and modifications as well as cognitive deficits [54]. Leite et al. has published a comprehensive review article on the adverse effects reported in over fifteen studies investigating complications that arose from introducing NPs into the brain environment [55]. Titanium oxide NP for instance was observed to affect mitochondrial function, triggering inflammation events in the brain, modifying synaptic plasticity and causing cognitive deficits [55][56][57]. ...
... Leite et al. has published a comprehensive review article on the adverse effects reported in over fifteen studies investigating complications that arose from introducing NPs into the brain environment [55]. Titanium oxide NP for instance was observed to affect mitochondrial function, triggering inflammation events in the brain, modifying synaptic plasticity and causing cognitive deficits [55][56][57]. Based on these reports, at this stage clinical safety is still a big concern in using NPs in brain delivery of therapeutics and should be addressed before treatments can be offered. ...
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The blood-brain barrier (BBB) is a highly specialised network of blood vessels that effectively separates the brain environment from the circulatory system. While there are benefits, in terms of keeping pathogens from entering the brain, the BBB also complicates treatments of brain pathologies by preventing efficient delivery of macromolecular drugs to diseased brain tissue. Although current non-invasive strategies of therapeutics delivery into the brain, such as focused ultrasound and nanoparticle-mediated delivery have shown various levels of successes, they still come with risks and limitations. This review discusses the current approaches of therapeutic delivery into the brain, with a specific focus on non-invasive methods. It also discusses the potential for aptamers as alternative delivery systems and several reported aptamers with promising preliminary results.
... The BBB is a unique feature of the human body, maintaining brain homeostasis, regulating the transport of compounds and preventing toxic substances from reaching the brain. This feature has made some conventional therapies ineffective, therefore the development of effective and novel approaches for the treatment of CNS disorders remains a serious challenge [204]. Some nanoparticles, are capable of crossing the BBB and accumulating in several CNS areas due to their unique small size (< 1 μm) and high surface area. ...
... Several in vitro and in vivo studies have demonstrated the neurotoxic effects of some nanoparticles inducing neuroinflammation and cognitive impairment [204]. Among various carbon nanomaterials, functionalized CNTs (fCNTs) have been shown to translocate into different subcellular compartments including brain cells [206]. ...
... While number of NMs can induce neurotoxicity, neuroinflammation, and cognitive deficits, polymeric nanoparticles are biocompatible and biodegradable having important characteristics for nanosafety of CNS drug delivery systems [89]. On the other hand, several reports have highlighted the fact of complement activation by PEG and surfactants being cause of serious detrimental effects in the brain [90,91]. ...
... On the other hand, the safety profiles of many polymeric NPs are still unknown. In the connection, polymeric NP-induced neurotoxicity in vivo, immunogenicity and a safe route of entry into brain without infliction of any damage have to be thoroughly investigated before their pharmaceutical application [89]. In the light of the above issue, relevant test models should be required in order: i) to assess the role of NMs/NPs in the development and progression of neurodegenerative disease; ii) to investigate the effects of NPs on neurodevelopment upon in utero exposure of foetuses [8] or neonatal exposure of pups; or iii) to study neuroendocrine disrupting effects during critical period being crucial for the development of neurodegenerative diseases. ...
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The development of nanomaterials (NMs) for applications in biomedicine inclusive of drug delivery as well as medical imaging is currently undergoing an enormous expansion. NMs may have many different forms and characteristics, depending on their size, chemical composition, manufacturing method, and surface modification. The use of NMs in the field of neurodegenerative diseases diagnosis and treatment implies the ability of NMs to cross the blood-brain barrier (BBB) and enter the central nervous system (CNS) in dependence on their physico-chemical properties, composition, and functionalization. The same properties that make the NMs beneficial for their applications may also affect their interactions with biological systems and have unintended consequences on human health. Several in vivo and in vitro studies have demonstrated that intentional exposure to NMs with potential use for diagnostic and therapeutic purposes might induce neurotoxic effects resulting in neuro-degeneration in different CNS regions. Recent evidence has indicated that neuro-endocrine disrupting effects by the action of NMs in dopaminergic, serotoninergic, and gonadotropic systems might be relevant to neuropathogenesis and neurodegeneration. In line with developmental origin of adult diseases, it is forewarning the evidence that pre-and post-natal exposure to different risk factors including NMs may lead to phenotypic heterogeneity and susceptibility to neurodegenerative diseases in later stages of the life. In the light of the above mentioned events, relevant test models are required to assess: i) the role of NMs in the development and progression of neurodegenerative disease; ii) the effects of NMs on neurodevelopment upon in utero exposure of foetuses or neonatal exposure of pups; or iii) the neuroendocrine disrupting effects during critical period being crucial for the development of neurodegenerative diseases. Early identification of potential negative features of NMs using interdisciplinary research approaches (biological, toxicological, clinical, engineering) could minimize the risk of newly designed/developed nanomedicines. NANOTOXICOLOGY AND SAFETY OF NANOMATERIALS Nanomaterials (NMs)/nanoparticles (NPs) cover a heterogeneous group of materials, including inorganic metal and metal oxide NMs, polymeric particulate materials and carbon-based NMs in a wide range of shapes. NMs possess unique physico-chemical properties, such as ultra small size (1-100 nm), large surface area to mass ratio, and high reactivity, which considerably distinguish from the bulk microscale material of the same composition. A wide range of NMs is already accessible on the market, and NMs for future applications like, novel robotic devices, targeted drug delivery systems, molecule-by-molecule design, and self-assembly structures are in the course of development. According to the European Commission (EC), the global quantity of NMs may achieve around 11.5 million tones with a market value of circa 20 bn € per year [1]. Nanotoxicology is a newly-formed discipline which focuses on the understanding of the properties of engineered NMs and their interactions with biological systems emphasized to elucidate the relationship between the physico-chemical properties of NMs and induction of toxic biological responses [2, 3]. Several leading scientists [4] have suggested five grand challenges that need to be achieved in line with safety and sustainability of the developed nanotechnologies (NTs). These require to develop: 1) instruments to monitor NM exposure in water and air; 2) validation of methods for the evaluation of the toxicity of NMs; 3) models predicting the impact of NMs on the human health and environment; 4) robust systems for evaluation of NMs impact on health and environment over entire life cycle; and 5) strategic programs intent on relevant risk-focused research. These challenges have been chosen to initiate strategic research aimed at the safety of NT. Many questions should be opened before NPs would be widely implemented in the marketplace. These are concerning the medicine and environment and say: will NPs induce nano-specific qualitatively distinct and novel toxic effects; how will be measured and predicted nano-specific effects; what will be the relationship between the shape, size, and surface chemistry of NPs on the one hand and their in vivo behavior on the other hand; how will be the NMs degraded or metabolized, will be the NMs and/or their degradation products effectively excreted from the body? At the European level, the discussion about NMs at legislative and scientific level has been ongoing for several years. To date, the current regulatory guidelines are
... Herein, the suitable biocompatible ocular drug delivery system depends on the target tissue, the route of administration, and the characteristics of the drug to be incorporated into the NPs. Despite all of the advantages, however, the high permeability of NPs pose a high risk, as shown in several brain studies [194]. For instance, zinc oxide NPs and the anatase phase of titanium dioxide can easily bypass the blood-brain barrier via multiple routes and induce neuroinflammation with the potential to be neurotoxic [195]. ...
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Recently, a considerable amount of literature has emerged around the theme of neuroinflammation linked to neurodegeneration. Glaucoma is a neurodegenerative disease characterized by visual impairment. Understanding the complex neuroinflammatory processes underlying retinal ganglion cell loss has the potential to improve conventional therapeutic approaches in glaucoma. Due to the presence of multiple barriers that a systemically administered drug has to cross to reach the intraocular space, ocular drug delivery has always been a challenge. Nowadays, studies are focused on improving the current therapies for glaucoma by utilizing nanoparticles as the modes of drug transport across the ocular anatomical and physiological barriers. This review offers some important insights on the therapeutic advancements made in this direction, focusing on the use of nanoparticles loaded with anti-inflammatory and neuroprotective agents in the treatment of glaucoma. The prospect of these novel therapies is discussed in relation to the current therapies to alleviate inflammation in glaucoma, which are being reviewed as well, along with the detailed molecular and cellular mechanisms governing the onset and the progression of the disease.
... What is notable in this context is that these three symptoms that show the strongest association with NP concentration are all directly linked to the central nervous system. Since NPs are capable of crossing the blood-brain barrier as well as travelling via the olfactory nerves from the nose to the brain, they are therefore also potentially hazardous to the CNS [58][59][60][61]. Neurotoxic effects caused by NPs can occur via several mechanisms including oxidative stress, autophagy, lysosome dysfunction, and through the activation of certain signaling pathways [62]. ...
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Submicroscopic nanoparticles (NPs) in air have received much attention due to their possible effects on health and wellbeing. Adverse health impacts of air pollution may not only be associated with level of exposure, but also mediated by the perception of the pollution and by beliefs of the exposure being hazardous. The aim of this study was to test a model that describes interrelations between NP pollution, perceived air quality, health risk perception, stress, and sick building syndrome. In the NanoOffice study, the level of NPs was measured and a survey on health risk perception was conducted among 260 employees in twelve office buildings in northern Sweden. Path analyses were performed to test the validity of the model. The data refute the model proposing that the NP exposure level significantly influences stress, chronic diseases, or SBS symptoms. Instead, the perceived exposure influences the perceived risk of NP, and the effect of perceived exposure on SBS and chronic disease is mediated by stress. There was little concern about nanoparticles, despite relatively high levels in some facilities. Perceived pollution and health risk perception may explain a large part of the environmentally induced symptoms and diseases, particularly in relatively low levels of pollution. The research results raise important questions on the physiologically or psychologically mediated health effects of air pollution.
... 5 However, fundamental understanding of issues related to toxicity and environmental impact of nanoscale materials is still under investigation. 6 During the past several years, there have been numerous toxicological investigations of airborne NPs and their impact on occupational health and the environment. [7][8][9] Experimental models have provided clear evidence that NPs can not only translocate to organs after inhalation, [10][11][12] but can also cause disruption of the blood-brain barrier through different administration routes, including the intravenous, the intraperitoneal, and the intracerebral route. ...
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Georgia Kastrinaki,1,* Christos Samsouris,2,* Efstratios K Kosmidis,3 Eleni Papaioannou,1 Athanasios G Konstandopoulos,1,4 George Theophilidis2 1Aerosol and Particle Technology Laboratory (APTL), CERTH/CPERI, Thessaloniki, Greece; 2Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3Laboratory of Physiology, Department of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece; 4Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece *These authors contributed equally to this work Abstract: The axonal translocation of two commonly used nanoparticles in medicine, namely CeO2 and SiO2, is investigated. The study was conducted on frog sciatic nerve fibers in an ex vivo preparation. Nanoparticles were applied at the proximal end of the excised nerve. A nerve stimulation protocol was followed for over 35 hours. Nerve vitality curve comparison between control and exposed nerves showed that CeO2 has no neurotoxic effect at the concentrations tested. After exposure, specimens were fixed and then screen scanned every 1 mm along their length for nanoparticle presence by means of Fourier transform infrared microscopy. We demonstrated that both nanoparticles translocate within the nerve by formation of narrow bands in the Fourier transform infrared spectrum. For the CeO2, we also demonstrated that the translocation depends on both axonal integrity and electrical activity. The speed of translocation for the two species was estimated in the range of 0.45–0.58 mm/h, close to slow axonal transportation rate. Transmission electron microscopy provided direct evidence for the presence of SiO2 in the treated nerves. Keywords: CeO2, SiO2, FTIR, nanoparticles, ex vivo electrophysiology, frog sciatic nerve, translocation
... It has been reported that nanosilver has an influence on mitochondrial function, generation of free radicals (AshaRani et al. 2009;Hussain et al. 2005;Singh and Ramarao 2012) and induction of apoptosis due to lowering of the cellular antioxidant glutathione (Piao et al. 2011). The high reactivity of NAg, resulting in enhanced ability to cross cell membranes, is of great concern in neuroscience due to the progressive development of theragnosis, a new concept in next-generation medicine that combines simultaneous diagnosis and therapy with the use of nanoparticles, including NAg (Leite et al. 2015). Since NAg have been shown to enter the brain by permeating the bloodbrain barrier (BBB) (Hoet et al. 2004;Sharma et al. 2009) and significantly accumulate in this organ, it is important to clarified their neurotoxic effects. ...
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Silver nanoparticles (NAg) have recently become one of the most commonly used nanomaterials. Since the ability of nanosilver to enter the brain has been confirmed, there has been a need to investigate mechanisms of its neurotoxicity. We previously showed that primary neuronal cultures treated with nanosilver undergo destabilization of calcium homeostasis via a mechanism involving glutamatergic NMDA receptors. Considering the fact that zinc interacts with these receptors, the aim of the present study was to examine the role of zinc in mechanisms of neuronal cell death in primary cultures. In cells treated with nanosilver, we noted an imbalance between extracellular and intracellular zinc levels. Thus, the influence of zinc deficiency and supplementation on nanosilver-evoked cytotoxicity was investigated by treatment with TPEN (a chelator of zinc ions), or ZnCl2, respectively. Elimination of zinc leads to complete death of nanosilver-treated CGCs. In contrast, supplementation with ZnCl2 increases viability of CGCs in a dose-dependent manner. Addition of zinc provided protection against the extra/intracellular calcium imbalance in a manner similar to MK-801, an antagonist of NMDA receptors. Zinc chelation by TPEN decreases the mitochondrial potential and dramatically increases the rate of production of reactive oxygen species. Our results indicate that zinc supplementation positively influences nanosilver-evoked changes in CGCs. This is presumed to be due to an inhibitory effect on NMDA-sensitive calcium channels.
... Different types of nanostructured materials have been investigated for application as nanocarriers such as quantum dots: metals, oxides, carbon-based nanoparticles, dendrimers, lipids, liposomes and polymer nanoparticles, while a significant number of such materials were approved or are in different stages of preclinical and clinical study [3,4]. In fact, the development of nanocarriers based on nanostructured materials for drug delivery application is the frontier of knowledge [5]. ...
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Background: Nanomedicine is currently exploited for manufacturing therapeutic DDS and treatments protocols for various diseases and disorders. To obtain DDS, different types of materials are used, from organic to inorganic, polar to non-polar, micro to nanomaterials from 0D to 3D structured materials, respectively. Many of these materials were extensively studied and reviewed in the literature. Objective: The objectives of this review is to make a clear overview on drug delivery systems depending several aspects related to delivery mechanisms, the type of supports, the active agents ant the potential applications in the prevention or treatment of various diseases. Results: Following aspects are extensively debated: synthesis issues, characteristics and potential uses of 0, 1, 2 and 3D drug delivery systems according to their nature and applications. These systems can be can be tailored according to the delivery mechanism (0-3D delivery) as well as by using more active agents, with more therapeutic activity or same activity but with different mechanisms of action. The size and morphology of the drug delivery system is essential, especially when talking about the internalization into the tumor cells while the mobility is especially dependent on the size. The influence of the nature of the supports and their polarity was extensively studied during the last decades, as well as the importance of the porosity and pore size, but only limited papers are devoted to the holistic analysis of the dimensionality of the support and the ways of delivering the active agents. Conclusion: This review is devoted to a holistic insight into the drug delivery systems, from a new, only marginally studied point of view, meaning the dimensionality of the drug delivery systems and the characteristics of the delivery.
... Circulating nanoparticles found in blood circulation depending on their material, size, charge, surface engineering, and others characteristics (Leite et al. 2015) can cross the blood-brain-barrier (BBB) and interact with the central nervous system (CNS) cells of the exposed animals (Hanada et al. 2014, Oberdörster et al. 2004. Different NPs such as silver NPs, gold NPs, manganese oxide NPs, iron oxide NPs, copper NPs, and TiO 2 NPs were described to cross BBB and accumulate in several CNS areas , Czajka et al. 2015, Elder et al. 2006, Skalska et al. 2015, Sousa et al. 2010, Wang et al. 2008b, Wu et al. 2013. ...
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Titanium dioxide nanoparticles (TiO2 NPs) are widely used for their whiteness and opacity in several applications such as food colorants, drug additives, biomedical ceramic, and implanted biomaterials. Research on the neurobiological response to orally administered TiO2 NPs is still limited. In our study, we investigate the effects of anatase TiO2 NPs on the brain of Wistar rats after oral intake. After daily intragastric administration of anatase TiO2 NPs (5–10 nm) at 0, 50, 100, and 200 mg/kg body weight (BW) for 60 days, the coefficient of the brain, acethylcholinesterase (AChE) activities, the level of interleukin 6 (IL-6), and the expression of glial fibrillary acidic protein (GFAP) were assessed to quantify the brain damage. The results showed that high-dose anatase TiO2 NPs could induce a downregulated level of AChE activities and showed an increase in plasmatic IL-6 level as compared to the control group accompanied by a dose-dependent decrease inter-doses, associated to an increase in the cerebral IL-6 level as a response to a local inflammation in brain. Furthermore, we observed elevated levels of immunoreactivity to GFAP in rat cerebral cortex. We concluded that oral intake of anatase TiO2 NPs can induce neuroinflammation and could be neurotoxic and hazardous to health.
... Biodegradable and biocompatible nanocarriers for drug delivery have been prepared from different polymers and protocols in order to reduce cytotoxicity [43], which, in part, may be attributed to metal components of existing therapies or NP accumulation in organs and poor clearance [38]. Poly-lactic acid NP (PLA-NP) are a type of polymeric NP with potential applications in nanomedicine as carriers of drugs, proteins and genes [29,75]. ...
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Background: Poly‑lactic acid nanoparticles (PLA‑NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA‑NP being considered biocompatible, data concerning alterations in cellular physiology are scarce. Methods: We conducted an extensive evaluation of PLA‑NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells’ proteome. We used non‑and green‑fluorescent PLA‑NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA‑NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin‑coated pits. Results: Cell viability and proliferation were not altered in response to PLA‑NP. Multiplex analysis of secreted mediators revealed a low‑level reduction of IL‑12p70 and vascular epidermal growth factor (VEGF) in response to PLA‑NP, while all other mediators assessed were unaffected. However, changes to the cells’ proteome were observed in response to PLA‑NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA‑NP, PLA‑NP enhanced susceptibility to STS‑induced cell death. Finally, PLA‑NP were rapidly internalized in association with clathrin‑coated pits, and, to a lesser extent, with lipid rafts. Conclusions: These data demonstrate that PLA‑NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro‑inflammatory mediators. However, PLA‑NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover, the pathways of PLA‑NP internalization we detected could contribute to the improvement of selective uptake strategies. Keywords: Nanoparticles, Drug delivery, Endocytosis, Lipid rafts, Clathrin‑coated pits
... For all of these applications, CNTs must be introduced to the brain, either by crossing the blood brain barrier (BBB) or by direct infusion, and toxicity is a concern. Studies investigating nanoparticles in the central nervous system (CNS) have found that diverse cytotoxic effects occur in the CNS after exposure to nanoparticles of various materials (Leite et al., 2015). Even gold nanoparticles, widely considered to exhibit little toxicity and high biocompatibility, can induce neurotoxic effects Toxicology in Vitro 41 (2017) 223-231 (Jung et al., 2014), which emphasizes the need for rigorous studies evaluating the potential neurotoxicity of nanomaterials. ...
Article
There is a growing interest in the use of multiwalled carbon nanotubes (MWCNTs) to treat diseases of the brain. Little is known about the effects of MWCNTs on human brain microvascular endothelial cells (HBMECs), which make up the blood vessels in the brain. In our studies, we evaluate the cytotoxicity of MWCNTs and acid oxidized MWNCTs, with or without a phospholipid-polyethylene glycol coating. We determined the cytotoxic effects of MWCNTs on both tissue-mimicking cultures of HBMECs grown on basement membrane and on monolayer cultures of HBMECs grown on plastic. We also evaluated the effects of MWCNT exposure on the capacity of HBMECs to form rings after plating on basement membrane, a commonly used assay to evaluate angiogenesis. We show that tissue-mimicking cultures of HBMECs are less sensitive to all types of MWCNTs than monolayer cultures of HBMECs. Furthermore, we found that MWCNTs have little impact on the capacity of HBMECs to form rings. Our results indicate that relative cytotoxicity of MWCNTs is significantly affected by the type of cell culture model used for testing, and supports further research into the use of tissue-mimicking endothelial cell culture models to help bridge the gap between in vitro and in vivo toxicology.
... Different types of nanoparticles have the ability to cross the BBBand reach the specific brain areas. However, several studies demonstrated the neurotoxic effects of different nanoparticles materials including neuro-inflammation and cognitive impairment (Leite et al., 2015).Therefore, efforts are being made to develop safer nano-carrier systems. Thus, polymeric NPs arise as a promising alternative due to their biocompatible and biodegradable properties. ...
... However, NPs are also known to induce neuroinflammation, neurotoxicity and cause damage to the cognitive process. 66 It is important to consider these hazardous effects these carriers could have on the body. For example, Zinc oxide NP's, can easily reach the brain through various routes and induce microglial cell death by NADPH-oxidase-independent ROS activity. ...
Article
Neuroinflammation, the condition associated with the hyper activity of immune cells within the CNS (central nervous system) has recently been linked to a host range of neurodegenerative disorders. Targeting neuroinflammation could be of prime importance as recent research highlights the beneficial aspects associated with modulating the inflammatory mediators associated with the CNS. One of the main obstructions in neuroinflammatory treatments is the hindrance posed by the Blood Brain Barrier for the delivery of drugs. Hence research has focused on novel modes of transport for drugs to cross the barrier through drug delivery and nanotechnology approaches. In this review we highlight the therapeutic advancement made in the field of neurodegenerative disorders by focusing on the effect neuroinflammation treatment has on these conditions.
... O cultivo de células vem se desenvolvendo exponencialmente desde o século XIX a ponto de, na atualidade, células cultivadas in vitro servirem como ferramentas terapêuticas 3,4,5 , modelos para estudo dos mais variados fenômenos e processos biológicos 6,7,8,9 e estudos toxicológicos 10,11,12,13,14 , entre outras aplicações. Ainda no contexto de cultivo celular e suas aplicações, é inegável a contribuição dos estudos in vitro na ciência regulatória, para a avaliação e registro de produtos. ...
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English and Portuguese (abstract and complete text) Introduction: Advances in scientific research are based on previously published findings. However, there is concern about the lack of Reproducibility in the biological researches in basic and preclinical areas, due to the repercussion on the population´s health. Because in vitro cultured cells are the basis for many toxicological and therapeutic studies, concern about their quality becomes paramount. Regarding microbiological contaminants, although bacteria and fungi are easily recognized, viruses and mycoplasmas are invisible under light microscopy. Another delicate issue would be the results generated with cells with modified identity. Objective: To discuss the main methodologies for assuring the quality of cells used in in vitro assays and to demonstrate how some world collections are structured to address this issue. Method: The scientific literature in the PubMed and Scielo databases and the webpage of different biological collections until December 2017. Results: It is recommended to apply the following techniques to detect contaminants in cell cultures: 1) virus : PCR and viral isolation; 2) mycoplasmas: PCR, bioluminescence and staining of cells with DNA affinity fluorophore; 3) human cell identity: the STR; 4) non-human cell identity: the Barcode. Conclusions: Considering all the investment applied in scientific research worldwide, the development of new methodologies alternatives to the use of animals and the critical consensus of the concept of quality, it is concluded that any laboratory should guarantee the control of purity and authenticity of its lineages. ----------------------------------------------------------------------------------------------------------------------------------- Português (com texto completo) Introdução: Avanços na pesquisa científica baseiam-se nas descobertas previamente publicadas. Entretanto, há preocupação com a falta de reprodutibilidade nas pesquisas biológicas das áreas básica e pré-clínica, em função da repercussão na saúde da população. Como células cultivadas in vitro constituem a base para muitos estudos toxicológicos e terapêuticos, a preocupação com a qualidade destas torna-se primordial. Com relação aos contaminantes microbiológicos, embora bactérias e fungos sejam facilmente reconhecidos, vírus e micoplasmas são invisíveis na microscopia óptica. Outro problema delicado seriam os resultados gerados com células com identidade modificada. Objetivo: Discutir as principais metodologias para a garantia da qualidade de células utilizadas em ensaios in vitro e demonstrar como algumas coleções mundiais estão estruturadas para tratar esta questão. Método: Levantamento da literatura científica nas bases de dados PubMed e Scielo e na página da web de diferentes coleções biológicas até dezembro de 2017. Resultados: Recomenda-se a aplicação das seguintes técnicas para detecção de contaminantes em cultivos celulares: 1) vírus: o PCR e o isolamento viral; 2) micoplasmas: o PCR, a bioluminescência e a coloração das células com fluoróforo com afinidade ao DNA; 3) identidade de células humanas: o STR; 4) identidade de células não humanas: o Barcode. Conclusões: Considerando todo o investimento aplicado em pesquisa científica em âmbito mundial, o desenvolvimento de novas metodologias alternativas ao uso de animais e o consenso crítico do conceito de qualidade, conclui-se que qualquer laboratório deve garantir o controle de pureza e autenticidade de suas linhagens.
... However, due to their extremely small size (< 100 nm), NPs can easily enter the human body through different pathways (Kao et al., 2012;Oberdorster et al., 2004) and can cross most biological membranes including the blood-brain barrier (Sarkar et al., 2017). Subsequently, NPs can accumulate in the brain (Simko and Mattsson, 2010) and could be at the origin of cerebral dysfunctions and diseases (Feng et al., 2015;Leite et al., 2015;Migliore et al., 2015;Struzynska and Skalska, 2018). ...
... Drug molecules can be entrapped inside of a hollow nanosphere or incorporated/absorbed into a nanosphere matrix. Polymeric nanospheres (NS) offer several benefits, such as maintaining therapeutic drug levels for a sustained time, better biocompatibility and biodegradation, and lower cytotoxicity, which are significant advantages over metallic NPs [5]. ...
Article
Polylactic acid-based nanoparticles are promising materials due to their tunable properties that are connected to surface modification. We have prepared polylactic acid nanospheres (PLA) with a non-magnetic phase (PLA loaded with various bovine serum albumin (BSA) concentrations) and magnetic phase (PLA loaded with magnetite nanoparticles coated with different amount of BSA (MFBSA)). The morphology, physico-chemical, magnetic and anti-amyloid properties were characterized by several biophysical methods. The amount of BSA used for PLA nanospheres or MFBSA modification played an important role in controlling the hydrodynamic size and zeta potential. In addition, magnetite loaded PLA nanospheres and MFBSA were all superparamagnetic. The potential of modified PLA nanospheres compared to MFBSA and 'naked' PLA to inhibit insulin amyloid fibrillation and destroy mature insulin fibrils was studied in vitro for samples with BSA/Fe3O4 weight ratio of 0.5. Destroying potential of samples was size–dependent, with the smallest MFBSA0.5 having the most significant effect. The strongest inhibitory effect on insulin fibrillation showed PLA-MFBSA0.5, slightly smaller than BSA modified PLA nanospheres.
... Despite AuNP use in medicine, some works have been evidencing their potential to induce cytotoxicity in different models. [82][83][84][85] The cytotoxic potential of AuNPs have been described using more sensitive techniques such as cellimpedance label-free systems and analysis of cell physiology besides cell viability such as release of inflammatory mediators, oxidative stress, and DNA damage. 82,[86][87][88][89] For example, AuNPs coated with chitosan promoted cytotoxicity and release of proinflammatory cytokines in THP1 cells. ...
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Nanomedicine is an emerging research area which has brought new possibilities and promising applications in image, diagnosis, and treatment. Nanoparticles (NPs) for medicinal purposes can be made of several material types such as silica, carbon, different polymers, and metals as silver, copper, titanium, and gold. Gold NPs (AuNPs) are the most studied and used, mostly due to their characteristics including simple preparation, controllable size and distribution, biocompatibility, good acceptance of surface modifications, and specific surface plasmon resonance (SPR). This study reviews the scientific literature regarding the potential applications of AuNPs in the development of new diagnostic and therapeutic strategies for nanomedicine, including their biomedical use as a drug carrier, as an agent in radio and phototherapy, and bioimaging for image diagnosis. While it becomes clear that much research remains to be done to improve the use of these nanoparticles, with particular concern for safety issues, the evidence from the literature already points to the great potential of AuNPs in nanomedicine.
... The limitations of porcine models are also exemplified by these studies in that for orthogonal comparisons, porcine in vivo models are less well characterised and readily studied due to the handling of such larger organisms in research settings. To support clinical studies and the translational significance of such studies in porcine models, coculturing and extensive biocompatibility studies [151] in such in vitro models should be considered at the earliest lead optimisation stages to support the clinical significance of such gathered data. ...
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Nanotheranostics constitute a novel drug delivery system approach to improving systemic, brain-targeted delivery of diagnostic imaging agents and pharmacological moieties in one rational carrier platform. While there have been notable successes in this field, currently, the clinical translation of such delivery systems for the treatment of neurological disorders has been limited by the inadequacy of correlating in vitro and in vivo data on blood–brain barrier (BBB) permeation and biocompatibility of nanomaterials. This review aims to identify the most contemporary non-invasive approaches for BBB crossing using nanotheranostics as a novel drug delivery strategy and current non-animal-based models for assessing the safety and efficiency of such formulations. This review will also address current and future directions of select in vitro models for reducing the cumbersome and laborious mandate for testing exclusively in animals. It is hoped these non-animal-based modelling approaches will facilitate researchers in optimising promising multifunctional nanocarriers with a view to accelerating clinical testing and authorisation applications. By rational design and appropriate selection of characterised and validated models, ranging from monolayer cell cultures to organ-on-chip microfluidics, promising nanotheranostic particles with modular and rational design can be screened in high-throughput models with robust predictive power. Thus, this article serves to highlight abbreviated research and development possibilities with clinical translational relevance for developing novel nanomaterial-based neuropharmaceuticals for therapy in CNS disorders. By generating predictive data for prospective nanomedicines using validated in vitro models for supporting clinical applications in lieu of requiring extensive use of in vivo animal models that have notable limitations, it is hoped that there will be a burgeoning in the nanotherapy of CNS disorders by virtue of accelerated lead identification through screening, optimisation through rational design for brain-targeted delivery across the BBB and clinical testing and approval using fewer animals. Additionally, by using models with tissue of human origin, reproducible therapeutically relevant nanomedicine delivery and individualised therapy can be realised.
... As discussed in the pathogenesis, it is clear that in bacterial meningitis, there is leakage of the blood CNS barriers with the disruption of the tight junctions [88]. There is an increase in the outflow resistance of cerebrospinal fluid resulting in the decrease in amount of CSF and also the P-glycoprotein activity is inhibited due to the presence of proinflammatory mediators like cytokines leading to reduction in efflux of drugs [89]. These factors in turn helps the increase in concentration of antibacterial drugs in the CSF which is not possible when meningeal inflammation is absent. ...
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Blood brain barrier is considered as the physiological barrier that restricts the entry of molecules into the central nervous system. The drug delivery mechanisms across blood brain barrier becomes important in case of infectious diseases like meningitis. It is the inflammation occurring in meninges due to infection with wide varieties of microbes. A drug used to target CNS for meningitis should cross this physiological barrier which often becomes a problem. In order to tackle this situation, drugs can be conjugated with nanoparticles like liposomes, dendrimers, polymeric nanoparticles etc. and can easily be targeted to the desired region. The use of nanoparticles overcome the barriers in the brain and enhance the bioavailability of the drug, reduce the systemic side effects, sustain the action of drug and specifically target the drug to required region. In this review, the current treatment strategies, novel nanoparticle approaches and their benefits are being addressed.
... Reports have shown liver toxicity [49], lung toxicity [50], reproductive system toxicity [51], and immune system toxicity [52]. Contrary to initial beliefs, over the past five years, there has been increasing evidence that inorganic oxide nanoparticles do cross the blood-brain barrier via a wide range of transport-related mechanisms [1,5,14,15,[53][54][55][56][57]. Unlike conventional drugs with a molar mass of 300-350 g/mol, nanoparticles have the ability to bypass the blood-brain barrier and enter neuronal tissue via other transport systems, or via diffusion if the particle size is small enough [54]. ...
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Recent developments in the design of advanced materials have furthered interest in the commercialization of new technologies. So the increased production of nanomaterials has increased concerns about their effects on human and environmental health. The evidence for health risks of nanoparticles has been demonstrated over the last decade, yet it is unclear if metal nanoparticles cause effects directly or indirectly. This chapter gives a brief review on the toxicology pathways, recommendations and methods for screening hazard testing of nanoparticles.
Chapter
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The neurovascular unit (NVU) is a complex functional and anatomical structure composed of endothelial cells and their blood-brain barrier (BBB) forming tight junctions. It represents an efficient barrier for molecules and drugs. However, it also prevents a targeted transport for the treatment of cerebral diseases. The uptake of ultrasmall nanoparticles as potential drug delivery agents was studied in a three-dimensional co-culture cell model (3D spheroid) composed of primary human cells (astrocytes, pericytes, endothelial cells). Multicellular 3D spheroids show reproducible NVU features and functions. The spheroid core is composed mainly of astrocytes, covered with pericytes, while brain endothelial cells form the surface layer, establishing the NVU that regulates the transport of molecules. After 120 h cultivation, the cells self-assemble into a 350 µm spheroid as shown by confocal laser scanning microscopy. The passage of different types of fluorescent ultrasmall gold nanoparticles (core diameter 2 nm) both into the spheroid and into three constituting cell types was studied by confocal laser scanning microscopy. Three kinds of covalently fluorophore-conjugated gold nanoparticles were used: One with fluorescein (FAM), one with Cy3, and one with the peptide CGGpTPAAK-5,6-FAM-NH2. In 2D cell co-culture experiments, it was found that all three kinds of nanoparticles readily entered all three cell types. FAM- and Cy3-labelled nanoparticles were able to enter the cell nucleus as well. The three dissolved dyes alone were not taken up by any cell type. A similar situation evolved with 3D spheroids: The three kinds of nanoparticles entered the spheroid, but the dissolved dyes did not. The presence of a functional blood-brain barrier was demonstrated by adding histamine to the spheroids. In that case, the blood-brain barrier opened, and dissolved dyes like a FITC-labelled antibody and FITC alone entered the spheroid. In summary, our results qualify ultrasmall gold nanoparticles as suitable carriers for imaging or drug delivery into brain cells (sometimes including the nucleus), brain cell spheroids, and probably also into the brain. Statement of Significance 3D brain spheroid model and its permeability by ultrasmall gold nanoparticles. We demonstrate that ultrasmall gold nanoparticles can easily penetrate the constituting cells and sometimes even enter the cell nucleus. They can also enter the interior of the blood-brain barrier model. In contrast, small molecules like fluorescing dyes are not able to do that. Thus, ultrasmall gold nanoparticles can serve as carriers of drugs or for imaging inside the brain.
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Nanotechnology is finding an increasing number of applications in industry, biology, and medicine. Nanoparticles' unique physicochemical properties allow for using these materials in cosmetics, sunscreens, household chemicals, alternative energy sources, membranes and filters, radiation protection, imaging and molecular diagnostics, as well as to optimize drug delivery, decrease toxicity, increase stability, and/or improve the efficacy of traditionally formulated drugs. Along with the increased application of nanotechnology comes the concerns about the environmental, occupational, and health safety of these materials. When nanoparticles are used for drug delivery, the toxicity of both the carrier and the drug has to be considered. Relocation of drug toxicity following the change in the tissue distribution of the particle-bound drug is a common challenge in the preclinical characterization of nanotechnology-based formulations. Exaggeration of the product immunotoxicity by nanosized particulate contaminants is another challenge common in biological therapeutics. Toxicology of nanomaterials is a broad subject, and many comprehensive reviews and books are already available. The purpose of this chapter is to provide a general overview of the field and highlight the most prominent findings. The chapter reviews systemic, pulmonary, cutaneous, and immunotoxicity of nanoparticles. Examples of both incidental nanoparticles and materials engineered for biomedical applications are discussed.
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Titanium dioxide nanoparticles (TiO2 NPs) have found many practical applications in industry and daily life. A widespread application of TiO2 NPs rises the question about safety of their use in the context of potential occupational, environmental and intentional exposure of humans and biota. TiO2 NPs easily enter the body through inhalation, cross blood-brain barrier and accumulate in the brain, especially in the cortex and hippocampus. Toxicity of these NPs and the molecular mechanisms of their action have been studied extensively in recent years. Studies showed that TiO2 NPs exposure resulted in microglia activation, reactive oxygen species production, activation of signaling pathways involved in inflammation and cell death, both in vitro and in vivo. Consequently, such action led to neuroinflammation, further brain injury. A, spatial recognition memory and locomotor activity impairment has been also observed. Copyright © 2015. Published by Elsevier Ltd.
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In the research field of nanoparticles, many studies demonstrated a high impact of the shape, size and surface charge, which is determined by the functionalization, of nanoparticles on cell viability and internalization into cells. This work focused on the comparison of three different nanoparticle types to give a better insight into general rules determining the biocompatibility of gold, Janus and semiconductor (quantum dot) nanoparticles. Endothelial cells were subject of this study, since blood is the first barrier after intravenous nanoparticle application. In particular, stronger effects on the viability of endothelial cells were found for nanoparticles with an elongated shape in comparison to spherical ones. Furthermore, a positively charged nanoparticle surface (NH2, CyA) leads to the strongest reduction in cell viability, whereas neutral and negatively charged nanoparticles are highly biocompatible to endothelial cells. These findings are attributed to a rapid internalization of the NH2-functionalized nanoparticles in combination with the damage of intracellular membranes. Interestingly, the endocytotic pathway seems to be a size-dependent process whereas nanoparticles with a size of 20 nm are internalized by caveolae-mediated endocytosis and nanoparticles with a size of 40 nm are taken up by clathrin-mediated internalization and macropinocytosis. Our results can be summarized to formulate five general rules, which are further specified in the text and which determine the biocompatibility of nanoparticles on endothelial cells. Our findings will help to design new nanoparticles with optimized properties concerning biocompatibility and uptake behavior with respect to the respective intended application.
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The development of safe and effective vaccines for cancer and infectious diseases remains a major goal in public health. Over the last two decades, controlled release of vaccine antigens and immunostimulant molecules has been achieved using nanometer or micron-sized delivery vehicles synthesized using biodegradable polymers. In addition to achieving a depot effect, enhanced vaccine efficacy using such delivery vehicles has been attributed to efficient targeting of antigen presenting cells such as dendritic cells. Biodegradable and biocompatible poly(lactic acid) and poly(lactic-co-glycolic acid) polymers belong to one such family of polymers that have been a popular choice of material used in the design of these delivery vehicles. This review summarizes research findings from ourselves and others highlighting the promise of poly(lactic acid)- and poly(lactic-co-glycolic acid)-based vaccine carriers in enhancing immune responses.
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In bacterial meningitis, excessive immune responses carry significant potential for damage to brain tissue even after successful antibiotic therapy. Bacterial meningitis is regarded primarily as the domain of innate immunity, and the role of lymphocytes remains unclear. We studied the contribution of lymphocytes to acute inflammation and neurodegeneration in experimental Toll-like receptor 2-driven meningitis, comparing wild-type mice with RAG-1-deficient mice that have no mature T and B lymphocytes. At 24 h after intrathecal challenge with the synthetic bacterial lipopeptide Pam3CysSK4, RAG-1-deficient mice displayed more pronounced clinical impairment and an increased concentration of neutrophils, reduced expression of interleukin-10 (IL-10) mRNA, and increased expression of CXCL1 mRNA in the cerebrospinal fluid. Conversely, neuronal loss in the dentate gyrus was reduced in RAG-1-deficient mice, and expression of IL-10, transforming growth factor β and CCL2 mRNA by microglia was increased compared to wild-type mice. Adoptive transfer of wild-type lymphocytes reversed the enhanced meningeal inflammation and functional impairment observed in RAG-1-deficient mice. Our findings suggest compartment-specific effects of lymphocytes during acute bacterial meningitis, including attenuation of meningeal inflammation and shifting of microglial activation toward a more neurotoxic phenotype.
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The complex network of neuronal cells in the retina makes it a potential target of neuronal toxicity - a risk factor for visual loss. With growing use of nanoparticles (NPs) in commercial and medical applications, including ophthalmology, there is a need for reliable models for early prediction of NP toxicity in the eye and retina. Metal NPs, such as gold and silver, gain much of attention in the ophthalmology community due to their potential to cross the barriers of the eye. Here, NP uptake and signs of toxicity were investigated after exposure to 20 and 80 nm Ag- and AuNPs, using an in vitro tissue culture model of the mouse retina. The model offers long-term preservation of retinal cell types, numbers and morphology and is a controlled system for delivery of NPs, using serum-free defined culture medium. AgNO3-treatment was used as control for toxicity caused by silver ions. These end-points were studied; gross morphological organization, glial activity, microglial activity, level of apoptosis and oxidative stress, which are all well described as signs of insult to neural tissue. TEM analysis demonstrated cellular- and nuclear uptake of all NP types in all neuronal layers of the retina. Htx-eosin staining showed morphological disruption of the normal complex layered retinal structure, vacuole formation and pyknotic cells after exposure to all Ag- and AuNPs. Significantly higher numbers of apoptotic cells as well as an increased number of oxidative stressed cells demonstrated NP-related neuronal toxicity. NPs also caused increased glial staining and microglial cell activation, typical hallmarks of neural tissue insult. This study demonstrates that low concentrations of 20 and 80 nm sized Ag- and AuNPs have adverse effects on the retina, using an organotypic retina culture model. Our results motivate careful assessment of candidate NP, metallic or-non-metallic, to be used in neural systems for therapeutic approaches.
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Drug delivery across the blood-brain barrier (BBB) is a major limitation in the treatment of central nervous system (CNS) disorders. Physiological factors such as phagocytic activity of the reticuloendothelial system and protein opsonization may limit the amount of brain delivered drug Several approaches are being investigated to improve drug delivery across the BBB. Nanoparticles (NP) are solid colloidal particles ranging in size from 1 to 1000 nm that are utilized as drug delivery agents. The use of NPs to deliver drugs to the brain across the blood-brain barrier (BBB) may provide a significant advantage to current strategies. The small size of the nanoparticles enables them to penetrate the BBB and facilitate the delivery of drugs across the barrier. Several mechanisms are involved in this process and various strategies are used based on different types of nanomaterial and combinations with therapeutic agents such as the use of liposomes, polymeric nanoparticles and non-viral vectors of nano-size for CNS gene therapy, etc. Nanotechnology is expected to reduce the need for invasive procedures for delivery of therapeutics to the CNS, some devices such as implanted catheters and reservoirs will still be needed. Nanomaterials can improve the safety and efficacy of such devices. Nano-engineered probes can deliver drugs at the cellular level using nanofluidic channels. Recently various drug delivery systems (e.g. liposomes, microspheres, nanoparticles, nanogels and bionanocapsules) have been used to enhance drug delivery to the brain. Recently, microchips and biodegradable polymers have become important in brain tumour therapy. The use of the physiological approach takes advantage of the transcytosis capacity of specific receptors expressed at the BBB. The low density lipoprotein receptor related protein (LRP) is the most adapted for such use with the engineered peptide compound (EPiC) platform incorporating the Angiopep peptide in new therapeutics the most advanced with promising data in the clinic. The current challenge is to develop drug delivery strategies that will allow the passage of drug molecules through the BBB in a safe and effective manner. Nanoparticles have been developed as an important strategy to deliver conventional drugs, recombinant proteins, vaccines and more recently nucleotides. Nanoparticulate delivery systems modify the kinetics, body distribution and drug release of an associated drug. Other effects are tissue or cell specific targeting of drugs and the reduction of unwanted side effects by a controlled release. Therefore nanoparticles in the pharmaceutical biotechnology sector improve the therapeutic index and provide solutions for future delivery problems for new classes of so called biotech drugs including recombinant proteins and oligonucleotides. This review provides an insight into some of the recent advances made in the field of brain drug delivery with the role of nanobiotechnology in drug delivery and drug targeting to Brain.
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Objective Gold nanoparticles have attracted enormous interest as potential theranostic agents. However, little is known about the long-term elimination and systemic toxicity of gold nanoparticles in the literature. Hollow gold nanospheres (HAuNS) is a class of photothermal conducting agent that have shown promises in photoacoustic imaging, photothermal ablation therapy, and drug delivery. It’s very necessary to make clear the biosafety of HAuNS for its further application. Methods We investigated the cytotoxicity, complement activation, and platelet aggregation of polyethylene glycol (PEG)-coated HAuNS (PEG-HAuNS, average diameter of 63 nm) in vitro and their pharmacokinetics, biodistribution, organ elimination, hematology, clinical chemistry, acute toxicity, and chronic toxicity in mice. Results PEG-HAuNS did not induce detectable activation of the complement system and did not induce detectable platelet aggregation. The blood half-life of PEG-HAuNS in mice was 8.19 ± 1.4 hr. The single effective dose of PEG-HAuNS in photothermal ablation therapy was determined to be 12.5 mg/kg. PEG-HAuNS caused no adverse effects after 10 daily intravenous injections over a 2-week period at a dose of 12.5 mg/kg per injection (accumulated dose: 125 mg/kg). Quantitative analysis of the muscle, liver, spleen, and kidney revealed that the levels of Au decreased 45.2%, 28.6%, 41.7%, and 40.8%, respectively, from day 14 to day 90 after the first intravenous injection, indicating that PEG-HAuNS was slowly cleared from these organs in mice. Conclusion Our data support the use of PEG-HAuNS as a promising photothermal conducting agent.
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Due to their inert property, gold nanoparticles (AuNPs) have drawn considerable attention; their biological application has recently expanded to include nanomedicine and neuroscience. However, the effect of AuNPs on the bioelectrical properties of a single neuron remains unknown. Here we present the effect of AuNPs on a single neuron under physiological and pathological conditions in vitro. AuNPs were intracellularly applied to hippocampal CA1 neurons from the mouse brain. The electrophysiological property of CA1 neurons treated with 5- or 40-nm AuNPs was assessed using the whole-cell patch-clamp technique. Intracellular application of AuNPs increased both the number of action potentials (APs) and input resistance. The threshold and duration of APs and the after hyperpolarization (AHP) were decreased by the intracellular AuNPs. In addition, intracellular AuNPs elicited paroxysmal depolarizing shift-like firing patterns during sustained repetitive firings (SRF) induced by prolonged depolarization (10 sec). Furthermore, low Mg2+-induced epileptiform activity was aggravated by the intracellular AuNPs. In this study, we demonstrated that intracellular AuNPs alter the intrinsic properties of neurons toward increasing their excitability, and may have deleterious effects on neurons under pathological conditions, such as seizure. These results provide some considerable direction on application of AuNPs into central nervous system (CNS).
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Rapid development of nanotechnologies and their applications in clinical research have raised concerns about the adverse effects of nanoparticles (NPs) on human health and environment. NPs can be directly taken up by organs exposed, but also translocated to secondary organs, such as the central nervous system (CNS) after systemic- or subcutaneous administration, or via the olfactory system. The CNS is particularly vulnerable during development and recent reports describe transport of NPs across the placenta and even into brain tissue using in vitro and in vivo experimental systems. Here, we investigated whether well-characterized commercial 20 and 80 nm Au- and AgNPs have an effect on human embryonic neural precursor cell (HNPC) growth. After two weeks of NP exposure, uptake of NPs, morphological features and the amount of viable and dead cells, proliferative cells (Ki67 immunostaining) and apoptotic cells (TUNEL assay), respectively, were studied. We demonstrate uptake of both 20 and 80 nm Au- and AgNPs respectively, by HNPCs during proliferation. A significant effect on the sphere size- and morphology was found for all cultures exposed to Au- and AgNPs. AgNPs of both sizes caused a significant increase in numbers of proliferating and apoptotic HNPCs. In contrast, only the highest dose of 20 nm AuNPs significantly affected proliferation, whereas no effect was seen on apoptotic cell death. Our data demonstrates that both Au- and AgNPs interfere with the growth profile of HNPCs, indicating the need of further detailed studies on the adverse effects of NPs on the developing CNS.
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Since recent data suggest that nanoparticles and modified vaccinia ankara (MVA) vectors could play a pivotal role in HIV-1 therapeutics and vaccine design, in an ex vivo model of human monocyte-derived dendritic cells (MDDCs), we compared two different loading strategies with HIV-1 vaccine vehicles, either viral or synthetic derived. We used polylactic acid (PLA) colloidal biodegradable particles, coated with HIV Gag antigens (p24), and MVA expressing Gag (rMVA-gag and rMVA-gag/trans membrane) or Tat, Nef and Rev genes (rMVA tat+rev and rMVA nef). PLA-p24 captured by MDDCs from HIV-1 individuals induced a slight degree of MDDC maturation, cytokine and chemokine secretion and migration towards a gradient of CCL19 chemokine and highly increased HIV-specific CD8+ T-cell proliferation compared with p24 alone. After complete maturation induction of PLA-p24-pulsed MDDCs, maximal migration towards a gradient of CCL19 chemokine and induction of HIV-specific T-cell proliferation (two-fold higher for CD4+ than CD8+) and cytokine secretion (IFN-γ and IL-2) in the co-culture were observed. Upon exposure to MVA-gag, MDDCs produced cytokines and chemokines and maintained their capacity to migrate to a gradient of CCL19. MDDCs infected with MVA-gag and MVA-gag trans-membrane were able to induce HIV-specific CD8+ proliferation and secretion of IFN-γ, IL-2, IL-6 and TNF-α. We conclude that both HIV antigens loading strategies (PLA-p24 nanoparticles or MVA expressing HIV genes) induce HIV-1-specific T-cell responses, which are able to kill autologous gag-expressing cells. Thus, they are plausible candidates for the development of anti-HIV vaccines.
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Gold nanoparticles are increasingly being employed in innovative biological applications thanks to their advantages of material- and size-dependent physics and chemical interactions with the cellular systems. On the other hand growing concern has emerged on the toxicity which would render gold-based nanoparticles harmful to cell cultures, animals and humans. Emerging attention is focused on the interaction of gold nanoparticles with nervous system, especially regarding the ability to overcome the blood brain barrier (BBB) which represents the major impediment to the delivery of therapeutics into the brain.We synthesized highly stable 2-mercapto-1-methylimidazole-stabilized gold-nanoparticles (AuNPs)-mmi to investigate their entry, accumulation and toxicity in vitro (SH-SY5Y human neuroblastoma cells) and in vivo (brain of C57BL/6 mice) through optical and electron microscopy. After incubation in the cell culture medium at the lowest dose of 0.1mg/ml the (AuNPs)-mmi nanoparticles were found compacted and recruited into endosome/lysosomes (1h) before their fusion (2h) and the onset of neuronal death by apoptosis (4h) as proved by TUNEL assay and caspase-3 immunoreactivity. The ability of (AuNPs)-mmi to cross the BBB was assessed by injection in the caudal vein of C57BL/6 mice. Among different brain regions, the nanoparticles were found in the CaudatoPutamen area, mainly in the striatal neurons 4h after injection. These neurons showed the typical hallmarks of apoptosis. Our findings provide, for the first time, the dynamic of 2-mercapto-1-methylimidazole nanogold uptake. The molecular mechanism which underlies the nanogold-driven apoptotic event is analyzed and discussed in order to take into account when designing nanomaterials to interface with biological structures.
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The introduction of combination antiretroviral treatment (cART) has significantly reduced the mortality secondary to opportunistic infections in HIV patients by restoring the immune system. In the central nervous system (CNS), there has also been benefit with a marked reduction of HIV associated dementia. However, the milder forms of HIV associated neurocognitive disorder (HAND), namely asymptomatic neurocognitive impairment and mild neurocognitive disorder, remain prevalent in the cART era. In this article, we will discuss how cART interacts with HAND in terms of clinical characteristics and biomarkers. We will then review the outcomes of recent clinical studies focused on the CNS penetrating antiretroviral regimens and some novel therapeutic approaches.
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Titanium dioxide nanoparticles (TiO2-NPs) are massively produced in the environment, and because of their wide usage, they are a potential risk of damage to human health. TiO2-NPs are often used as additives for paints, papers, and foods. The central nervous system (CNS), including hippocampal regions, is potentially susceptible targets for TiO2-NPs. This study aimed to determine the effects of exposure to TiO2-NPs during pregnancy on hippocampal cell proliferation and the learning and memory of offspring. Pregnant Wistar rats received intragastric TiO2-NPs (100mg/kg body weight) daily from gestational day (GD) 2 to (GD) 21. Animals in the control group received the same volume of distilled water via gavage. After delivery, the one-day-old neonates were deeply anesthetized and weighed. They were then killed and the brains of each group were collected. Sections of the brains from the rat offspring were stained using Ki-67 immunolabeling and the immunohistochemistry technique. Some of the male offspring (n=12 for each group) were weaned at postnatal day (PND21), and housed until adulthood (PND60). Then the learning and memory in animals of each group were evaluated using passive avoidance and Morris water maze tests. The immunolabeling of Ki-67 protein as a proliferating cell marker showed that TiO2-NPs significantly reduced cell proliferation in the hippocampus of the offspring (P<0.05). Moreover, both the Morris water maze test and the passive avoidance test showed that exposure to TiO2-NPs significantly impaired learning and memory in offspring (P<0.05). These results may provide basic experimental evidence for a better understanding of the neurotoxic effects of TiO2-NPs on neonatal and adult brains.
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Health impacts of inhalation exposure to engineered nanomaterials have attracted increasing attention. In this paper, integrated analytical techniques with high sensitivity were used to study the brain translocation and potential impairment induced by intranasally instilled copper nanoparticles (CuNPs). Mice were exposed to CuNPs in three doses (1, 10, 40 mg/kg bw). The body weight of mice decreased significantly in the 10 and 40 mg/kg group (p < 0.05) but recovered slightly within exposure duration. Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that CuNPs could enter the brain. Altered distribution of some important metal elements were observed by synchrotron radiation X-ray fluorescence (SRXRF). H&E Staining and immunohistochemical analysis showed that CuNPs produced damages to nerve cells and astrocyte might be the one of the potential targets of CuNPs. The changes of neurotransmitter levels in different brain regions demonstrate that the dysfunction occurred in exposed groups. These data indicated that CuNPs could enter the brain after nasal inhalation and induced damages to the central nervous system (CNS). Integration of effective analytical techniques for systematic investigations is a promising direction to better understand the biological activities of nanomaterials.
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Transport of PEGylated silica nanoparticles (PSiNPs) with diameters of 100 nm, 50 nm and 25 nm across the blood-brain barrier (BBB) was evaluated using an in vitro BBB model based on mouse cerebral endothelial cells (bEnd.3) cultured on transwell inserts within a chamber. In vivo animal experiments were further performed by noninvasive in vivo imaging and ex vivo optical imaging after injection via carotid artery. Confocal fluorescence studies were carried out in order to evaluate the uptake of PSiNPs by brain endothelial cells. The results showed that PSiNPs can traverse the BBB in vitro and in vivo. The transport efficiency of PSiNPs across BBB was found to be size-dependent, with increased particle size resulting in decreased efficiency. This work points to the potential application of small sized silica nanoparticles in brain imaging or drug delivery.
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For decades, biomedical and pharmaceutical researchers have worked to devise new and more effective therapeutics to treat diseases affecting the central nervous system (CNS). The blood-brain barrier effectively protects the brain, but poses a profound challenge to drug delivery across this barrier. Many traditional drugs cannot cross the blood-brain barrier in appreciable concentrations, with less than 1% of most drugs reaching the CNS, leading to a lack of available treatments for many CNS diseases, such as stroke, neurodegenerative disorders, and brain tumors. Due to the ineffective nature of most treatments for CNS disorders, the development of novel drug delivery systems is an area of great interest and active research. Multiple novel strategies show promise for effective CNS drug delivery giving potential for more effective and safer therapies in the future. This review outlines several novel drug delivery techniques including intranasal drug delivery, nanoparticles, drug modifications, convection-enhanced infusion, and ultrasound-mediated drug delivery. It also assesses possible clinical applications, limitations, and examples of current clinical and pre-clinical research for each of these drug delivery approaches. Improved CNS drug delivery is extremely important, and will allow for improved treatment of CNS diseases, causing improved therapies for those who are affected by CNS diseases. This article is protected by copyright. All rights reserved.
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Nanomedicine formulations such as biodegradable nanoparticles (nps) and liposomes offer several advantages over traditional routes of administration: due to their small size, nanocarriers are able to selective accumulate inside tumours or inflammatory tissues, resulting in improved drug efficacy and reduced side effects. To further augment targeting ability of nanoparticles towards tumour cells, specific ligands or antibodies that selectively recognize biomarkers over-expressed on cancer cells, can be attached to the surface either by chemical bond or by hydrophilic/hydrophobic interactions. In the present work, Herceptin (HER), a monoclonal antibody (mAb) able to selectively recognize HER-2 over-expressing tumour cells (such as breast and ovarian cancer cells) was absorbed on the surface of nanoparticles through hydrophilic/hydrophobic interactions. Nps were prepared by a modified single emulsion solvent evaporation method with five different polymers: three commercial polyesters (poly(ε-caprolactone) (PCL), poly (D,L-lactide) (PLA) and poly (D,L-lactide-co-.glycolide) (PLGA)) and two novel biodegradable polyesterurethanes (PURs) based on Poly(ε-caprolactone) blocks, synthesized with different chain extenders (1,4-cyclohexane dimethanol (CDM) and N-Boc-serinol). Polyurethanes were introduced as matrix-forming materials for nanoparticles due to their high chemical versatility, which allows tailoring of the materials final properties by properly selecting the reagents. All nps exhibited a small size and negative surface charge, suitable for surface functionalisation with mAb through hydrophilic/hydrophobic interactions. The extent of cellular internalization was tested on two different cell lines: MCF-7 and SK-BR-3 breast cancer cells showing a normal and a high expression of the HER-2 receptor, respectively. Paclitaxel, a model anti-neoplastic drug was encapsulated inside all nps and release profiles and cytoxicity on SK-BR-3 cells were also assessed. Interestingly, PUR nps were superior to commercial polyester-based nps in terms of higher cellular internalization and cytotoxic activity on the tested cell lines. Results obtained warrants further investigation on the application of these PUR nps for controlled drug delivery and targeting.
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Unlabelled: Antiviral therapy using nucleoside reverse transcriptase inhibitors (NRTIs) is neurotoxic and has low efficiency in eradication of HIV-1 harbored in central nervous system (CNS). Previously, we reported that active 5'-triphosphates of NRTIs encapsulated in cationic nanogels (nano-NRTIs) suppress HIV-1 activity more efficiently than NRTIs and exhibit reduced mitochondrial toxicity [Vinogradov SV, Poluektova LY, Makarov E, Gerson T, Senanayake MT. Nano-NRTIs: efficient inhibitors of HIV type-1 in macrophages with a reduced mitochondrial toxicity. Antivir Chem Chemother. 2010; 21:1-14. Makarov E, Gerson T, Senanayake T, Poluektova LY, Vinogradov. Efficient suppression of Human Immunodeficiency Virus in Macrophages by Nano-NRTIs. Antiviral Res. 2010; 86(1):A38-9]. Here, we demonstrated low neurotoxicity and excellent antiviral activity of nano-NRTIs decorated with the peptide (AP) binding brain-specific apolipoprotein E receptor. Nano-NRTIs induced lower levels of apoptosis and formation of reactive oxygen species, a major cause of neuron death, than free NRTIs. Optimization of size, surface decoration with AP significantly increased brain accumulation of nano-NRTIs. The efficient CNS delivery of nano-NRTIs resulted in up to 10-fold suppression of retroviral activity and reduced virus-associated inflammation in humanized mouse model of HIV-1 infection in the brain. Our data provide proof of the advanced efficacy of nano-NRTIs as safer alternative of current antiviral drugs. From the clinical editor: This team of investigators demonstrated low neurotoxicity and excellent anti-HIV activity of nano-nucleoside reverse transcriptase inhibitors decorated with the peptide (AP) binding brain-specific apolipoprotein E receptor, providing proof of enhanced efficacy and a safer alternative compared with current antiviral drugs.
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Wilson's disease, the most common inherited disorder of copper metabolism, is a recessive genetic condition. The clinical presentation of Wilson's disease is very variable. It is characterised by low serum copper and caeruloplasmin concentrations coupled with the pathological accumulation of copper in the tissues. However, there are diagnostic difficulties and these are discussed. The current value of DNA diagnosis, both in gene tracking in families or as applied to de novo cases, is examined. Wilson's disease can be treated successfully but treatment must be life long. Patients are best treated by specialist centres with experience and expertise in the condition.
Article
The blood-brain barrier (BBB), which is formed by the brain capillary wall, greatly hinders the development of new drugs for the brain. Over the past decades, among the various receptor-mediated endogenous BBB transport systems, the strategy of using transferrin or anti-transferrin receptor antibodies to facilitate brain drug delivery system is of particular interest. However, the application of large proteins still suffers from the drawbacks including synthesis procedure, stability, and immunological response. Here we explored a B6 peptide discovered by phase display as a substitute for transferrin, and conjugated it to PEG-PLA nanoparticles (NP) with the aim to enhance the delivery of neuroprotective drug across the BBB for the treatment of Alzheimer's disease. B6-modified NP (B6-NP) exhibited significantly higher accumulation in brain capillary endothelial cells via lipid raft-mediated and clathrin-mediated endocytosis. In vivo, fluorescently labeled B6-NP exhibited much higher brain accumulation when compared with NP. Administration of B6-NP encapsulated neuroprotective peptide NAPVSIPQ (NAP) to Alzheimer's disease mouse models showed excellent amelioration in learning impairments, cholinergic disruption and loss of hippocampal neurons even at lower dose. These findings together suggested that B6-NP might serve as a promising DDS for facilitating the brain delivery of neuropeptides.
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Upconversion luminescent hollow Y2 O3 :Yb(3+) /Er(3+) nanospheres can be synthesized by an etching-free process, which hold promising potential for applications such as drug delivery, angiography, and high-contrast cellular as well as tissue imaging, with no damage from radiation or toxicity.
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By taking advantage of the excessively upregulated expression of neuropilin (NRP) on the surface of both glioma cells and endothelial cells of angiogenic blood vessels, the ligand of NRP with high affinity - tLyp-1 peptide, which also contains a CendR motif ((R/K)XX(R/K)), was functionalized to the surface of PEG-PLA nanoparticles (tLyp-1-NP) to mediate its tumor homing, vascular extravasation and deep penetration into the glioma parenchyma. The tLyp-1-NP was prepared via a maleimide-thiol coupling reaction with uniformly spherical shape under TEM and particle size of 111.30 ± 15.64 nm. tLyp-1-NP exhibited enhanced cellular uptake in both human umbilical vein endothelial cells and Rat C6 glioma cells, increased cytotoxicity of the loaded PTX, and improved penetration and growth inhibition in avascular C6 glioma spheroids. Selective accumulation and deep penetration of tLyp-1-NP at the glioma site was confirmed by in vivo imaging and glioma distribution analysis. The longest survival was achieved by those mice bearing intracranial C6 glioma treated with PTX-loaded tLyp-1-NP. The findings here strongly indicate that tLyp-1 peptide-functionalized nanoparticulate DDS could significantly improve the efficacy of paclitaxel glioma therapy.
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Gold nanoparticles (AuNPs) have a number of physical properties that make them appealing for medical applications. For example, the attenuation of X-rays by gold nanoparticles has led to their use in computed tomography imaging and as adjuvants for radiotherapy. AuNPs have numerous other applications in imaging, therapy and diagnostic systems. The advanced state of synthetic chemistry of gold nanoparticles offers precise control over physicochemical and optical properties. Furthermore gold cores are inert and are considered to be biocompatible and non-toxic. The surface of gold nanoparticles can easily be modified for a specific application and ligands for targeting, drugs or biocompatible coatings can be introduced. AuNPs can be incorporated into larger structures such as polymeric nanoparticles or liposomes that deliver large payloads for enhanced diagnostic applications, efficiently encapsulate drugs for concurrent therapy or add additional imaging labels. This array of features has led to the afore-mentioned applications in biomedical fields, but more recently in approaches where multifunctional gold nanoparticles are used for multiple methods, such as concurrent diagnosis and therapy, so called theranostics. The following review covers basic principles and recent findings in gold nanoparticle applications for imaging, therapy and diagnostics, with a focus on reports of multifunctional AuNPs.
Article
Combination antiretroviral therapy (ART) has markedly reduced morbidity and mortality among HIV-infected individuals but not the prevalence of HIV-associated neurocognitive disorders (HAND). Several conditions may be responsible for the high prevalence of cognitive impairment, including incomplete suppression of HIV in nervous system by some antiretrovirals. Since individuals with HAND have a lower quality of life, worse medication adherence, and a higher risk of death, optimizing treatment of neurocognitive outcomes is an important goal of therapy. Optimization of ART to treat the CNS is limited, in part, by the ability of many antiretrovirals to cross the blood-brain barrier (BBB). Differences between antiretrovirals in crossing the BBB - and by extension differences in their concentrations in the brain - may explain inter-individual differences in susceptibility to HAND among treated individuals. This manuscript reviews relevant data on the CSF pharmacology of antiretrovirals and accumulating evidence that the use of drugs that reach therapeutic concentrations in the CNS are the best options to prevent and treat HIV-induced brain injury. Despite the importance of healthy cognition to the quality of patients' lives, consensus treatment guidelines for HAND have yet to be formulated more than two decades after its first description. Formulating widely accepted recommendations for CNS-optimized treatment strategies requires a level of clinical evidence not yet developed but studies are underway to address this shortcoming.
Article
Nanotechnology is an area of growing public interest. Its attractiveness stems from the promise offered socially and economically by the recent significant advances in nanotechnological development. Nanotechnology has already begun to be incorporated into the daily lives, but the level of its technological impact has yet to become clear. As a result, new properties never previously observed in these materials in either bulk form or as part of larger scale entities can be harnessed. Chemical processes can be tailored to a desired application, such as the enhancement of biocompatibility of implantable materials, for example. Due to their greater surface area per volume, nanomaterials can exhibit higher reactivity, increased capacity for mechanical strength, or magnetic or electrical properties. Targeted molecular imaging is important for a wide range of diagnostic purposes, such as the identification of inflammatory loci, the localization and staging of tumors, the visualization of vascular structures or specific disease states, and the examination of anatomy.
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It has recently been reported that iron oxide nanoparticles (Fe(3)O(4)-NPs, 30nm) have the ability to translocate directly from the olfactory nerve to the brain. The striatum and hippocampus are important structures in the brain and are associated with the development of Parkinson's and Alzheimer's diseases. Therefore, it is critical to evaluate Fe(3)O(4)-NPs and their potential to confer striatum and hippocampus neurotoxicity. This study focuses on the effects of Fe(3)O(4)-NPs on the striatum and hippocampus, including oxidative injury and the accumulation and retention of Fe(3)O(4)-NPs. This study also explores the molecular mechanism of oxidative damage in dopaminergic neurons; we were able to assess the neurotoxic effects of Fe(3)O(4)-NPs by incubating dopaminergic neurons with radioactive Fe(3)O(4)-NPs. A regional distribution of Fe(3)O(4)-NPs was observed in rat brains after the particles were intranasally instilled for seven days. The particles were found to be deposited at particularly high concentrations in the rat striata and hippocampi. Over half of the Fe(3)O(4)-NPs were retained in the striata for a minimum of 14 days, and may have induced oxidative damage to the region. However, no injuries were observed in the hippocampi. These in vitro studies demonstrate that Fe(3)O(4)-NPs may decrease neuron viability, trigger oxidative stress, and activate JNK- and p53-mediated pathways to regulate the cell cycle and apoptosis. These results also suggest that environmental exposure to Fe(3)O(4)-NPs may play a role in the development of neurodegenerative diseases.
Article
Once nanoparticles enter the central nervous system (CNS), they immediately encounter a complex environment of resident microglial immune cell and neurons. In the present study, NPs of 20-60nm in diameter (SiO(2)-NPs, TiO(2)-NPs, HAP-NPs and Fe(3)O(4)-NPs) were evaluated for their ability to induce microglia-mediated neurodegeneration. The microglia were directly exposed to NPs. The results showed that both TiO(2)-NPs and HAP-NPs induced significant iNOS expression, resulting in NO release from the microglia. The expression levels of MCP-1 and MIP-1α were also upregulated. These activation effects were accompanied by the activation of the transcription factor NF-κB. In addition, the secretion levels of TNF-α, IL-1β and IL-6 were variably increased by all four NPs. Subsequently, the cell-free supernatants from microglia monocultures were harvested and tested for their ability to stimulate PC12 cells. The results demonstrated that microglia-derived soluble factors induced by TiO(2)-NPs suppressed Th gene expression, and those by TiO(2)-NPs and HAP-NPs caused cytotoxicity in PC12 cells. Taken together, these results suggest that the NPs induced microglial activation and subsequently caused the release of proinflammatory factors that contributed to the dysfunction and cytotoxicity in PC12 cells.
Article
Nanoparticulate drug delivery system possesses distinct advantages for brain drug delivery. However, its amount that reach the brain is still not satisfied. Cell-penetrating peptides (CPPs), short peptides that facilitate cellular uptake of various molecular cargo, would be appropriate candidates for facilitating brain delivery of nanoparticles. However, such effect could be deprived by the rapid systemic clearance of CPPs-functionalized nanoparticles due to their positive surface charge. Penetratin (CPP with relatively low content of basic amino acids) was here functionalized to poly(ethylene glycol)-poly(lactic acid) nanoparticles (NP) to achieve desirable pharmacokinetic and biodistribution profiles for brain drug delivery. The obtained penetratin-NP showed a particle size of 100 nm and zeta potential of -4.42 mV. The surface conjugation of penetratin was confirmed by surface chemical compositions analysis via X-ray photo electron spectroscopy. In MDCK-MDR cell model, penetratin-NP presented enhanced cellular accumulation via both lipid raft-mediated endocytosis and direct translocation processes with the involvement of Golgi apparatus, lysosome and microtubules. In vivo pharmacokinetic and biodistribution studies showed that penetratin-NP exhibited a significantly enhanced brain uptake and reduced accumulation in the non-target tissues compared with low-molecular-weight protamine (CPP with high arginine content)-functionalized nanoparticles. These data strongly implicated that penetratin-NP might represent a promising brain-targeting drug delivery system. The findings also provided an important basis for the optimization of brain drug delivery systems via surface charge modulation.
Article
Objectives: Long-acting nanoformulated antiretroviral therapy (nanoART) with improved pharmacokinetics, biodistribution and limited systemic toxicities will likely improve drug adherence and access to viral reservoirs. Design: Atazanavir and ritonavir crystalline nanoART were formulated in a poloxamer-188 excipient by high-pressure homogenization. These formulations were evaluated for antiretroviral and neuroprotective activities in humanized NOD/scid-IL-2Rgc (NSG) mice. Methods: NanoART-treated NSG mice were evaluated for drug biodistribution, pharmacodynamics and toxicity. CD34 human hematopoietic stem cells were transplanted at birth in replicate NSG mice. The mice were infected with HIV-1ADA at 5 months of age. Eight weeks later, the infected animals were treated with weekly subcutaneous injections of nanoformulated ATV and RTV. Peripheral viral load, CD4 T-cell counts and lymphoid and brain histopathology and immunohistochemistry tests were performed. Results: NanoART treatments by once-a-week injections reduced viral loads more than 1000-fold and protected CD4 T-cell populations. This paralleled high ART levels in liver, spleen and blood that were in or around the human minimal effective dose concentration without notable toxicities. Importantly, examination of infected brain subregions showed that nanoART elicited neuroprotective responses with detectable increases in microtubule-associated protein-2, synaptophysin and neurofilament expression when compared to untreated virus-infected animals. Therapeutic interruptions produced profound viral rebounds. Conclusion: Long-acting nanoART has translational potential with sustained and targeted efficacy and with limited systemic toxicities. Such success in drug delivery and distribution could improve drug adherence and reduce viral resistance in infected people.
Article
Several studies have reported the adverse effects of nano-CuO on hippocampal CA1 neuron, whereas little has been known about nano-CuO neurotoxicity in vivo. In the present study, we investigated the effects of nano-CuO on spatial cognition and electrophysiological alterations in rats. In addition, histological and biochemical changes in rat's hippocampus were measured as well. Morris water maze (MWM) test showed that learning and memory abilities in nano-CuO-treated group were weakened significantly. The long-term potentiation (LTP) test exhibited that field excitatory postsynaptic potentials (fEPSPs) slopes were significantly lower in nano-CuO-treated group compared to that in control group. Furthermore, the levels of ROS and malonaldehyde (MDA) in hippocampal homogenate of nano-CuO-treated group were considerably enhanced while the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were statistically reduced. Moreover, the enhanced 4-hydroxynonenal (HNE) and caspase-3 implied the progression of apoptosis in the hippocampus. The results suggested that the neuronal damage, induced by impairing oxidation-antioxidation homeostasis, led to the impairment of hippocampal LTP, which was associated with the poor performance of animals in behavior tests.
Article
Molecular diffusion in the extracellular space (ECS) plays a key role in determining tissue physiology and pharmacology. The blood-brain barrier regulates the exchange of substances between the brain and the blood, but the diffusion properties of molecules at this blood-brain interface, particularly around the astrocyte endfeet, are poorly characterized. In this study, we used 2-photon microscopy and acute brain slices of mouse neocortex and directly assessed the diffusion patterns of fluorescent molecules. By observing the diffusion of unconjugated and 10-kDa dextran-conjugated Alexa Fluor 488 from the ECS of the brain parenchyma to the blood vessels, we find various degrees of diffusion barriers at the endfeet: Some allow the invasion of dye inside the endfoot network while others completely block it. Detailed analyses of the time course for dye clearance support the existence of a tight endfoot network capable of acting as a diffusion barrier. Finally, we show that this diffusion pattern collapses under pathological conditions. These data demonstrate the heterogeneous nature of molecular diffusion dynamics around the endfeet and suggest that these structures can serve as the diffusion barrier. Therefore, astrocyte endfeet may add another layer of regulation to the exchange of molecules between blood vessels and brain parenchyma.
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The blood-brain barrier (BBB) is not simply a physical barrier but a regulatory interface between the central nervous system (CNS) and immune system. The BBB both affects and is affected by the immune system and connects at many levels with the CNS, including the following: (1) the BBB transports cytokines and secretes various substances with neuroinflammatory properties; (2) transporters are altered in disease states including traumatic injury, Alzheimer's disease and inflammatory processes; (3) cytokines and other immune secretions from the cells comprising the BBB are both constitutive and inducible; (4) immune cells are transported across the BBB by the highly regulated process termed diapedesis, which involves communication and interactions between the brain endothelial cells and the immune cells; (5) the neuroimmune system has various effects on the BBB, including modulation of important transport systems and in extreme pathological conditions even disruption of the BBB, and (6) the brain-to-blood efflux transporter P-glycoprotein is altered in inflammatory conditions, thus affecting drug delivery to the brain. In summary, the BBB is an interactive interface that regulates and defines many of the ways that the CNS and the immune system communicate with one another.