Nanotechnological applications for the treatment of neurodegenerative disorders

Nanotechnology employs engineered materials or devices that interact with biological systems at a molecular level and could revolutionize the treatment of neurodegenerative disorders (NDs) by stimulating, responding to and interacting with target sites to induce physiological responses while minimizing side-effects. Conventional drug delivery systems do not provide adequate cyto-architecture restoration and connection patterns that are essential for functional recovery in NDs, due to limitations posed by the restrictive blood–brain barrier. This review article provides a concise incursion into the current and future applications of nano-enabled drug delivery systems for the treatment of NDs, in particular Alzheimer's and Parkinson's diseases, and explores the application of nanotechnology in clinical neuroscience to develop innovative therapeutic modalities for the treatment of NDs.     

The intracellular uptake of CD95 modified paclitaxel-loaded poly(lactic-co-glycolic acid) microparticles

The CD95/CD95L receptor-ligand system is mainly recognised in the induction of apoptosis. However, it has also been shown that CD95L is over-expressed in many cancer types where it modulates immune-evasion and together with its receptor CD95 promotes tumour growth. Here, we show that CD95 surface modification of relatively large microparticles >0.5 μm in diameter, including those made from biodegradable polylactic-co-glycolic acid (PLGA), enhances intracellular uptake by a range of CD95L expressing cells in a process akin to phagocytosis. Using this approach we describe the intracellular uptake of microparticles and agent delivery in neurons, medulloblastoma, breast and ovarian cancer cells in vitro. CD95 modified paclitaxel-loaded PLGA microparticles are shown to be significantly more effective compared to conventional paclitaxel therapy (Taxol) at the same dose in subcutaneous medulloblastoma (???P < 0.0001) and orthotopic ovarian cancer xenograft models where a >65-fold reduction in tumour bioluminescence was measured after treatment (?P = 0.012). This drug delivery platform represents a new way of manipulating the normally advantageous tumour CD95L over-expression towards a therapeutic strategy. CD95 functionalised drug carriers could contribute to the improved function of cytotoxics in cancer, potentially increasing drug targeting and efficacy whilst reducing toxicity.     

Paclitaxel and etoposide-loaded Poly (lactic-co-glycolic acid) microspheres fabricated by coaxial electrospraying for dual drug delivery

Abstract

In this study, we fabricated paclitaxel (PTX) and etoposide (ETP) loaded Poly (lactic-co-glycolic acid) (PLGA) microspheres with core–shell structures and particle sizes ranging from 1 to 4?µm by coaxial electrospraying. The microspheres were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM). The drug loading rate and entrapment efficiency of the microspheres were detected by high performance liquid chromatograph (HPLC). Moreover, the drug release profiles and degradation of drug-loaded PLGA microspheres in vitro were investigated, respectively. The distinct layered structure that existed in the manufactured core–shell microspheres can be observed by TEM. The in vitro release profiles indicated that the PLGA/PTX?+?ETP (PLGA/PE) microspheres exhibited the controlled release of two drugs in a sequential manner. Cell Counting Kit-8 was used to detect the toxic and side effects of the microspheres on bone tumor cells. PTX and ETP for combination drug therapy loaded microspheres had more cytotoxic effect on saos-2 osteosarcoma cells than the individual drugs. In conclusion, core–shell PLGA microspheres by electrospraying for combination drug therapy is promising for medicine applications, the PLGA/PE microspheres have some potential for osteosarcoma treatment.     

Targeted delivery of antibiotics to intracellular chlamydial infections using PLGA nanoparticles

Chlamydia trachomatis and Chlamydia pneumoniae are intracellular bacterial pathogens that have been shown to cause, or are strongly associated with, diverse chronic diseases. Persistent infections by both organisms are refractory to antibiotic therapy. The lack of therapeutic efficacy results from the attenuated metabolic rate of persistently infecting chlamydiae in combination with the modest intracellular drug concentrations achievable by normal delivery of antibiotics to the inclusions within which chlamydiae reside in the host cell cytoplasm. In this research, we evaluated whether nanoparticles formulated using the biodegradable poly(d-L-lactide-co-glycolide) (PLGA) polymer can enhance the delivery of antibiotics to the chlamydial inclusion complexes. We initially studied the trafficking of PLGA nanoparticles in Chlamydia-infected cells. We then evaluated nanoparticles for the delivery of antibiotics to the inclusions. Intracellular trafficking studies show that PLGA nanoparticles efficiently concentrate in inclusions in both acutely and persistently infected cells. Further, encapsulation of rifampin and azithromycin antibiotics in PLGA nanoparticles enhanced the effectiveness of the antibiotics in reducing microbial burden. Combination of rifampin and azithromycin was more effective than the individual drugs. Overall, our studies show that PLGA nanoparticles can be effective carriers for targeted delivery of antibiotics to intracellular chlamydial infections.     

Mitochondria as the target for neuroprotectors

Contemporary methods of treatment of neurodegenerative diseases (NDs) are limited and mainly symptomatic. Despite difference in particular clinical manifestations, NDs have a number of common features, the main of which is death of certain neuron population. The authors suppose that mitochondria and the phenomenon of mitochondrial permeability transition (MPT), playing the key role in cell death, may be a perspective target for the search of drugs with a capability of delaying the neurological deficit associated with NDs. The authors have demonstrated that some neurotoxins which are widely used to model neurodegenerative conditions are able to potentiate or even induce MPT. The neuroprotective effect of widely used cognition-enhancing drugs, such as tacrin, memantine, dimebon, N-acethylserotonine, and extract of Gingko biloba), may also be a result of their interaction with mitochondria. Thus, the search of drugs capable of preventing or breaking the cascade of cell death as a result of MPT suppression and, at the same time, compensating for the impaired brain functions, is very topical.     

Effects of surfactants on the properties of PLGA nanoparticles

The objective of this study was to investigate the physical characteristics of poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) coated with two surfactants, Pluronic or the commonly used polyvinyl alcohol (PVA); and determine their in vitro efficiency as drug carriers for cancer therapy. Free surfactant cytotoxicity results indicated that Pluronic F127 (PF127) was most cytocompatible among the Pluronics tested and hence chosen for coating PLGA NPs for further studies. Release studies using doxorubicin (DOX) as a drug model showed sustained release of DOX from both PVA- and PF127-coated PLGA NPs (PLGA-PVA and PLGA-PF127, respectively) over 28 days. Further, there was no significant difference in human dermal fibroblasts and human aortic smooth muscle cell survival when exposed to both types of NPs. Cellular uptake studies demonstrated that uptake of both nanoparticle types was dose-dependent for both prostate and breast cancer cells. However, these cancer cells internalized more PLGA-PF127 NPs than PLGA-PVA NPs. Moreover, studies showed that drug-loaded PLGA-PF127 NPs not only killed more cancer cells than drug-loaded PLGA-PVA NPs, but also overcame drug resistance in LNCaP, MDA-MB-231, and MDA-MB-468 cancer cells on re-exposure. These results indicate that PLGA-PF127 NPs can form a promising system that not only delivers anti-cancer drugs, but also overcomes drug resistance, which is prevalent in most cancer cells.     

Superior in vitro anticancer effect of biomimetic paclitaxel and triptolide co-delivery system in gastric cancer

As a well-known anticancer drug, paclitaxel (PTX), a first-line chemotherapeutic agent, remains unsatisfactory for gastric cancer therapy. It is reported that triptolide (TPL) could enhance the anti-gastric cancer effect of PTX. Considering the poor solubility of both drugs, we developed a red blood cell membrane-biomimetic nanosystem, an emerging tool in drug delivery, to co-load paclitaxel and triptolide (red blood cell membrane coated PTX and TPL co-loaded poly(lactic-co-glycolic acid) [PLGA] nanoparticles, RP(P/T)). The successful preparation was confirmed in terms of particle size, morphology, and surface markers assays. This biomimetic system could prolong circulation and escape immune surveillance. And these properties were verified by stability, in vitro drug release, and cellular uptake assays. Moreover, the MTT and colony formation assays demonstrated the superior anti-proliferation effect of the RP(P/T) to free drugs. The enhanced antitumor effects of RP(P/T) on migration and invasion were also evaluated by wound-healing and transwell assays. Overall, the bionic co-delivery nanoplatform with improved efficacy in vitro is a promising therapy for gastric cancer.     

Nanocomposites for neurodegenerative diseases: hydrogel-nanoparticle combinations for a challenging drug delivery

Neurodegenerative disorders are expected to strike social and health care systems of developed countries heavily in the coming decades. Alzheimer's and Parkinson's diseases (AD/PD) are the most prevalent neurodegenerative pathologies, and currently their available therapy is only symptomatic. However, innovative potential drugs are actively under development, though their efficacy is sometimes limited by poor brain bioavailability and/or sustained peripheral degradation. To partly overcome these constraints, the development of drug delivery devices made by biocompatible and easily administrable materials might be a great adjuvant. In particular, materials science can provide a powerful tool to design hydrogels and nanoparticles as basic components of more complex nanocomposites that might ameliorate drug or cell delivery in AD/PD. This kind of approach is particularly promising for intranasal delivery, which might increase brain targeting of neuroprotective molecules or proteins. Here we review these issues, with a focus on nanoparticles as nanocomponents able to carry and tune drug release in the central nervous system, without ignoring warnings concerning their potential toxicity.     

Nanodiamonds-mediated doxorubicin nuclear delivery to inhibit lung metastasis of breast cancer

Lung metastasis is one of the greatest challenges for breast cancer treatment. Here, a nanodiamonds (NDs)-mediated doxorubicin (DOX) delivery system was first designed to inhibit the lung metastasis of breast cancer effectively. DOX was non-covalently bound to NDs via physical adsorption in an aqueous solution, then DSPE-PEG 2K was coated to the NDs-DOX complex (NDX) to increase the dispersibility and prolong the circulation time. DSPE-PEG 2K coating NDX (DNX) displayed high drug loading and excellent ability to deliver DOX to the nucleus, thereby significantly enhancing cytotoxicity and inducing cell apoptosis. Furthermore, DNX showed good histocompatibility and could improve drug accumulation in lung, as a result, markedly inhibited the lung metastasis of breast cancer. The high anti-metastasis efficacy with the decreased systemic toxicity suggested that DNX could be a promising drug delivery system for the therapy of lung metastasis of breast cancer.     

Design and characterisation of new nanoparticulate polymer blends for drug delivery

The aim of the present work was the design of novel nanoparticle compositions based on poly(lactic acid/glycolic acid) (PLGA): poloxamer and PLGA: poloxamine blend matrices. For this purpose, we have applied a modified solvent diffusion technique that allows the preparation of the nanoparticles without the use of high energy sources. Nanoparticles have been prepared with different PLGA: poloxamer and PLGA: poloxamine ratios using PEO-derivatives with different molecular weights (Mw) and hydrophilia-lipophilia balance (HLB) values. Our results show that the physicochemical characteristics of the nanoparticles, such as size and zeta potential, are influenced by the type of PEO-derivative associated to the PLGA matrix. The 1H-NMR analysis of the different nanoparticle compositions showed that the extent of incorporation of the PEO-derivative depends strongly on its HLB and also on the nanoparticles preparation conditions. The capacity of these nanoparticles as drug delivery devices was evaluated using bovine insulin as a model drug. The insulin-encapsulation efficiency was shown to be dependent on the composition of the nanoparticles, those containing hydrophilic PEO-derivatives being the most effective in entrapping the drug molecules. The formation of the blend system displayed positive effects on the release characteristics of the nanoparticles. Nanoparticles exhibited a reduced initial burst and a nearly linear, constant release rate over a time period of two weeks.     

Delivery of gold nanoparticles to the brain by conjugation with a peptide that recognizes the transferrin receptor

The treatment of Alzheimer's disease and many other brain-related disorders is limited because of the presence of the blood-brain barrier, which highly regulate the crossing of drugs. Metal nanoparticles have unique features that could contribute to the development of new therapies for these diseases. Nanoparticles have the capacity to carry several molecules of a drug; furthermore, their unique physico-chemical properties allow, for example, photothermal therapy to produce molecular surgery to destroy tumor cells and toxic structures. Recently, we demonstrated that gold nanoparticles conjugated to the peptide CLPFFD are useful to destroy the toxic aggregates of β-amyloid, similar to the ones found in the brains of patients with Alzheimer's disease. However, nanoparticles, like many other compounds, have null or very low capacity to cross the blood-brain barrier. In order to devise a strategy to improve drug delivery to the brain, here we introduced the peptide sequence THRPPMWSPVWP into the gold nanoparticle-CLPFFD conjugate. This peptide sequence interacts with the transferrin receptor present in the microvascular endothelial cells of the blood-brain barrier, thus causing an increase in the permeability of the conjugate in brain, as shown by experiments in?vitro and in?vivo. Our results are highly relevant for the therapeutic applications of gold nanoparticles for molecular surgery in the treatment of neurodegenerative diseases such as Alzheimer's disease.     

Effect of thiol functionalization on the hemo-compatibility of PLGA nanoparticles

In this study, an attempt was made to reduce the interaction of poly(D,L-lactic acid/glycolic acid) (PLGA) nanoparticles with the opsonins and phagocytic cells upon functionalization with thiol groups. Terminal carboxylic groups in PLGA were conjugated to the amino group of cysteine and nanoparticles were prepared by solvent evaporation technique. Detailed in vitro investigations were performed on PLGA and cysteine modified PLGA (Cys-PLGA) nanoparticles to asses their blood compatibility. The effect of these nanoparticles on the release of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) from human macrophage cells were evaluated. Thiolation was confirmed by fourier transform infrared spectroscopy and Ellman's assay; both PLGA and modified nanoparticles had average size in the range of 250 nm. Thiolation was an effective strategy in reducing the protein adsorption, complement activation, and platelet activation of PLGA nanoparticles. PLGA and modified PLGA nanoparticles were compatible with the blood cells and no hemolytic effect was detected. Particles were noncytotoxic on L929 cells and release of proinflammatory cytokines from macrophage cells was rather unaffected with the modification strategy. From these studies, it seems that thiolation of particulate delivery system is an interesting approach in manipulating the blood-particle interactions and appears to be an effective candidate for injectable drug delivery applications.     

The uptake and intracellular fate of PLGA nanoparticles in epithelial cells

Biodegradable polymer nanoparticles (NPs) are a promising approach for intracellular delivery of drugs, proteins, and nucleic acids, but little is known about their intracellular fate, particularly in epithelial cells, which represent a major target. Rhodamine-loaded PLGA (polylactic-co-glycolic acid) NPs were used to explore particle uptake and intracellular fate in three different epithelial cell lines modeling the respiratory airway (HBE), gut (Caco-2), and renal proximal tubule (OK). To track intracellular fate, immunofluorescence techniques and confocal microscopy were used to demonstrate colocalization of NPs with specific organelles: early endosomes, late endosomes, lysosomes, endoplasmic reticulum (ER), and Golgi apparatus. Confocal analysis demonstrated that NPs are capable of entering cells of all three types of epithelium. NPs appear to colocalize with the early endosomes at short times after exposure (～2 h), but are also found in other compartments within the cytoplasm, notably Golgi and, possibly, ER, as time progressed over the period of 4–24 h. The rate and extent of uptake differed among these cell lines: at a fixed particle/cell ratio, cellular uptake was most abundant in OK cells and least abundant in Caco-2 cells. We present a model for the intracellular fate of particles that is consistent with our experimental data.     

Culture of pyramidal neural precursors,neural stem cells,and fibroblasts on various biomaterials

Abstract

A combinatory approach using biomaterials together with cells may improve the efficacy of cell therapy for treatment of various diseases/indications. In the current study, we cultured pyramidal neural precursors (PNPs), neural stem cells (NSCs), and fibroblasts on different materials that included fibrin, collagen, hyaluronic acid (HA), sciatic nerves, and matrigel, to search for the most suitable biomaterial for culture of each cell type. Collagen was fabricated in both an aligned collagen-poly (lactic-co-glycolic acid) (PLGA) composite and an alveolate form; fibrin and hyaluronic acid were made in an aligned form only. Pyramidal neurons have strong projection ability and have potentials in neural circuit reconstruction. However, PNPs showed difficulty in attaching to and growing neurites on most of the materials tested, except for matrigel, in which neurite growth was observed in a three dimentional culture. NSCs and derivatives hold promise in treating neurological diseases. On aligned fibrin, NSCs could differentiate and grow neurites in a directional manner before fibrin was degraded in 2 days. On aligned collagen-PLGA, induced neural stem cells (iNSCs) could survive and differentiate for at least 2 weeks, but the neurites failed to extend in an aligned way. Fibroblast graft are useful in many indications, such as in skin burns. Fibroblasts generally grew better on the tested materials than did the neural cells, and fibroblasts could grow directionally on the aligned fibrin and scattered around on the alveolate collagen. The study provided information which may be used to further optimize the materials to support culture of each type of cells.     

Design and characterisation of new nanoparticulate polymer blends for drug delivery

The aim of the present work was the design of novel nanoparticle compositions based on poly(lactic acid/glycolic acid) (PLGA): poloxamer and PLGA: poloxamine blend matrices. For this purpose, we have applied a modified solvent diffusion technique that allows the preparation of the nanoparticles without the use of high energy sources. Nanoparticles have been prepared with different PLGA: poloxamer and PLGA: poloxamine ratios using PEO-derivatives with different molecular weights (M _w) and hydrophilia–lipophilia balance (HLB) values. Our results show that the physicochemical characteristics of the nanoparticles, such as size and zeta potential, are influenced by the type of PEO-derivative associated to the PLGA matrix. The ¹H-NMR analysis of the different nanoparticle compositions showed that the extent of incorporation of the PEO-derivative depends strongly on its HLB and also on the nanoparticles preparation conditions. The capacity of these nanoparticles as drug delivery devices was evaluated using bovine insulin as a model drug. The insulin-encapsulation efficiency was shown to be dependent on the composition of the nanoparticles, those containing hydrophilic PEO-derivatives being the most effective in entrapping the drug molecules. The formation of the blend system displayed positive effects on the release characteristics of the nanoparticles. Nanoparticles exhibited a reduced initial burst and a nearly linear, constant release rate over a time period of two weeks.     

Stabilizer-free poly(lactide-co-glycolide) nanoparticles for multimodal biomedical probes

Apart from the reported PLGA submicro- and microspheres with broad size distribution, we have successfully developed a methodology using nanoprecipitation to prepare different sizes of PLGA nanoparticles with narrow size distributions. The newly developed PLGA nanoparticles could be readily modified with hydrophilic biomaterials on their surface and entrap hydrophobic drugs into their interiors. The encapsulation of FITC inside PLGA nanoparticles displayed a controlled release of drug system. The surfaces of the FITC entrapped PLGA nanoparticles were conjugated with quantum dots to serve as bimodal imaging probes. For nuclear transport, combination of nuclear localization signal (NLS) and PLGA nanoparticles, PLGA nanoparticles could successfully enter into HeLa cells nuclei. From tissue uptake results, PLGA nanoparticles had more uptaken by brain and liver than other tissues. The iron oxide nanoparticles-conjugated PLGA nanoparticle showed high efficiency of relaxivities r2 and could be used as the powerful magnetic resonance imaging (MRI) agents.     

Co-delivery of chemotherapeutic drugs with vitamin E TPGS by porous PLGA nanoparticles for enhanced chemotherapy against multi-drug resistance

We report a strategy to make use of poly(lactic-co-glycolic acid) nanoparticle (PLGA NPs) for co-delivery of docetaxel (DTX) as a model anticancer drug together with vitamin E TPGS. The latter plays a dual role as a pore-forming agent in the nanoparticles that may result in smaller particle size, higher drug encapsulation efficiency and faster drug release, and also as a bioactive agent that could inhibit P-glycoprotein to overcome multi-drug resistance of the cancer cells, The DTX-loaded PLGA NPs of 0, 10, 20 and 40% TPGS were prepared by the nanoprecipitation method and then characterized for their size and size distribution, surface morphology, physical status and encapsulation efficiency of the drug in the NPs. All four NPs were found of size ranged 100–120 nm and EE ranged 85–95% at drug loading level around 10%. The in vitro evaluation showed that the 48 h IC₅₀ values of the free DTX and the DTX-loaded PLGA NPs of 0, 10, 20% TPGS were 2.619 and 0.474, 0.040, 0.009 μg/mL respectively, which means that the PLGA NPs formulation could be 5.57 fold effective than the free DTX and that the DTX-loaded PLGA NPs of 10 or 20% TPGS further be 11.85 and 52.7 fold effective than the DTX-loaded PLGA NPs of no TPGS (therefore, 66.0 and 284 fold effective than the free DTX). Xenograft tumor model and immunohistological staining analysis further confirmed the advantages of the strategy of co-delivery of anticancer drugs with TPGS by PLGA NPs.     

Synthesis of cholic-acid-carrying polymer and in-vitro evaluation of hepatoma-targeting nanoparticles decorated with the polymer

The specific interaction between bile acids and the bile acids transporters provides a promising way for hepatoma-targeted drug delivery. We synthesized an amphipathic polymer containing cholic acid (CA), the main bile acids in body, and prepared CA-functionalized nanoparticles to target hepatoma cells. Poly-[3-(4-vinylbenzonate)-7, 12-dihydroxy-5-cholan-24-oic acid] (PVBCA) was synthesized by introducing methyl cholate onto polyvinyl benzoate polymer backbone, and was characterized by ¹H-NMR, FT-IR, and GFC. PVBCA can be incorporated onto PLGA nanoparticles surface via the emulsion-solvent evaporation procedure, resulting in the nanoparticles carrying CA moieties on their surface. The binding of CA moieties to the bile acids’ transporters on the cell membrane enhances the cellular uptake of the nanoparticles significantly. The SMMC-7721 cell uptake of PVBCA-decorated nanoparticles increases with amount of incorporated PVBCA and is 2- to 2.8-fold higher than that of the normal PLGA nanoparticles. By exclusion of specific endocytosis pathways using chemical inhibitors, we found that the uptake mechanism of PVBCA-decorated nanoparticles was mainly attributed to clathrin-and-caveolae-independent endocytosis, which was distinct from that of PLGA nanoparticles. The present study provides a simple and versatile method for hepatoma-targeted delivery of nanoparticles.     

星型M-PLGA纳米药物制剂用于宫颈癌治疗的研究

目的 本研究合成了一种星型的甘露醇引发的聚（乳酸-羟基乙酸）共聚物（M-PLGA）,旨在提供一种新型的纳米制剂用于宫颈癌的治疗.方法 这种新型的共聚物通过开环聚合合成,利用核磁共振仪进行表征.采用改进的纳米沉淀法制备载多烯紫杉醇M-PLGA纳米粒并在扫描电镜下观察纳米粒的形态.结果 M-PLGA纳米粒粒径分布较窄,在人宫颈癌Hela细胞中的摄取水平要高于PLGA纳米粒.载多烯紫杉醇的M-PLGA纳米粒对Hela细胞的毒性显著高于商用的泰素帝和载多烯紫杉醇的PLGA纳米粒,证明星型M-PLGA聚合物作为纳米药物载体优于线型PLGA聚合物;同时,星型M-PLGA的载药量也明显高于线型聚合物.结论 星型M-PLGA共聚物可作为一种极具潜力的用于宫颈癌治疗的纳米载体材料.     

The use of deoxycholic acid to enhance the oral bioavailability of biodegradable nanoparticles

Oral delivery of nanoparticles encapsulating drugs and proteins remains a challenging route for administration due to the many barriers in the gastrointestinal tract that limit bioavailability. We hypothesized that bile salts could be used to improve the bioavailability of poly(lactide-co-glycolide) (PLGA) nanoparticles by protecting them during their transport through the gastrointestinal tract and enhancing their absorption by the intestinal epithelia. A deoxycholic acid emulsion is shown to protect PLGA nanoparticles from degradation in acidic conditions and enhance their permeability across a Caco-2 cell monolayer, an in vitro model of human epithelium. Oral administration of loaded PLGA nanoparticles to mice, using a deoxycholic acid emulsion, produced sustained levels of the encapsulant in the blood over 24-48 h with a relative bioavailability of 1.81. Encapsulant concentration was highest in the liver, demonstrating a novel means for targeted delivery to the liver by the oral route.