[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to determine the effectiveness of the systemic administration of high dose erythropoietin (EPO) in a 6‑hydroxydopamine (6‑OHDA)‑ induced rat model. Rats were divided into 7 groups. Groups 1‑4 were administered daily EPO doses of 0; 2,500; 5,000 and 10,000 U/kg via intraperitoneal injection (i.p.) for 5 days. The EPO concentration in cerebrospinal fluid (CSF) was determined by enzyme‑linked immunosorbent assay (ELISA) and western blot analysis. The dose of 10,000 U/kg was then selected for subsequent experiments. In group 5, rats received saline via medial forebrain bundle (MFB). In group 6, rats received 6‑OHDA via MFB. In group 7, an EPO concentration of 10,000 U/kg was constantly administered i.p. for 5 days to rats prior to 6‑OHDA injection via MFB. Behavioral analysis was performed for groups 5‑7 by rat rotation tests. The number of tyrosine hydroxylase (TH)‑immunopositive cells in the substantia nigra (SN) was measured by immuno-cyto-chemistry. The activation of c‑Jun N‑terminal kinase (JNK), extracellular signal‑regulated kinase (ERK), p38 mitogen‑activated protein kinases (MAPKs) and caspase‑3 signaling in rats were analyzed using western blotting. The results showed that there was a significant increase in EPO levels in the CSF in 10,000 U/kg group compared with the 2,500 and 5,000 U/kg groups (P<0.01). Significantly fewer rotational counts were obtained in rats that were pretreated with EPO compared with saline‑pretreated 6‑OHDA‑lesioned rats (P<0.001). The dopaminergic neurons in the 6‑OHDA‑lesioned SN were also increased in the EPO‑pretreated rats when compared with control rats (P<0.01). Western blot analysis revealed that EPO inhibited the 6‑OHDA‑induced activation of JNK, ERK, p38 MAPK and caspase‑3 signaling in the rat model. In conclusion, systemic administration of a high dose of EPO exerted neuroprotective effects in reversing behavioral deficits associated with Parkinson's disease and prevented loss of the dopaminergic neurons through the MAPK pathway.
International Journal of Molecular Medicine 06/2014; · 1.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Introduction: Overexpression of VEGF has been identified to be associated with many pathologic processes such as tumors and retinopathy. Inhibiting uncontrolled growth of VEGF is a promising strategy to treat these diseases. Currently small molecule inhibitors and monoclonal antibodies are the primary treatment. However, complex development, short half-life, limited effectiveness and potential systemic side effects limited their applications. Highly effective and safe therapeutic technologies are highly desirable to meet the growing clinical needs. RNA interference (RNAi) technology, inhibits special gene activity at the post transcriptional level and reduces the expression of relevant proteins, holding great potential due to its easy design and high efficacy. Some molecules based on RNAi have been investigating in different clinical trials. Areas covered: In this article, we review and consider current advances in the application of RNAi technology and potential future clinical strategies. Expert opinion: RNAi technology has a promising future in anti-VEGF treatment, most of the investigations are encouraging and exciting. More anti-VEGF candidates will enter clinical trials and may be a novel therapeutic strategy.
Expert Opinion on Drug Delivery 06/2014; · 4.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel method has been developed to protect Recombinant Human Growth Hormone (rhGH) in poly (lactic-co-glycolic acid) (PLGA) microspheres using an aqueous phase/ aqueous phase emulsion and S/O/W multi-emulsion method. This method develops a novel rhGH sustained-release system, which is based on the combination of rhGH-loaded dextran microparticles and PLGA microspheres. The process to fabricate rhGH-loaded dextran microparticles involves an aqueous phase/aqueous phase emulsion system formed at the reduced temperature. RhGH was first dissolved in water together with dextran and polyethylene glycol, followed by stirring at the speed of 2000 rpm for 20-30 s at 0°C, and then a freezing process could enable the dextran phase to separate from the continuous PEG phase and rhGH could preferentially be loaded with dextran. The sample after freezing and phase separation was then lyophilized to powder and washed with dichloromethane to remove the PEG. Once loaded in the dextran microparticles (1-4 μm in diameter), rhGH gained resistance to interface tensions and was encapsulated into PLGA microspheres without aggregation thereafter. RhGH released from PLGA microspheres was in a sustained manner with minimal burst and maximally reduced incomplete release in vitro. Single subcutaneous injection of rhGH-loaded PLGA microspheres to rats resulted in a stable plasma concentration for 30 days avoiding the drug concentration fluctuations after multiple injections of protein solutions. In a hypophysectomized rat model, the IGF-1 and bodyweight results showed that there were higher than the levels obtained for the sustained release formulation by W/O/W for 40 days. These results suggest that the microsphere delivery system had the potential to be an injectable depot for sustained-release of the biocompatible protein of rhGH.
European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 06/2014; · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A challenge in gene therapy is the efficient delivery of DNA/siRNA to the diseased cells. The physicochemical characteristics of siRNA, such as high molecular weight, negative charges and hydrophilic nature--prevent passive diffusion across the plasma membrane for most cells. A therapeutically feasible carrier for intra-cellular delivery of gene materials should accomplish a series of tasks such as: condensing nucleic acid, protecting nucleic acid from leaking in vivo, facilitating endosome escape and releasing DNA/siRNA to the target site. To meet these requirements, an efficient gene vector based on polycation synthesis for siRNA delivery both in vitro and in vivo was developed.
The polymer was synthesized by 1, 4-butanediol bis (chloroformate) and PEI 800 Da to form PEI-Bu which could condense siRNA at the N/P ratio of 38.35 or above. The size of the nanoparticles was 100-300 nm and zeta potential was in the range of 10-30 mV at different N/P ratios. The nanoparticles can achieve the ability of cellular uptake and the silencing efficiency was about 46.63% in SMMC-7721 cell line which was generated to stably express GL3 luciferase gene. The cytotoxicity of the polyplex nanoparticles was almost negligible on SMMC-7721 cells by MTT assay, indicating that the reduced luciferase expression was the effect of RNAi, not the influence of cytotoxicity of polyplexes. The polyplex nanoparticle formulated by PEI-Bu and siRNA at N/P ratio of 115.05 was injected into the SMMC-7721 tumor bearing mice locally and the expression of luciferase can reduce to 63.17% compared with control group.
Results in this study suggested that PEI-Bu polycation might provide a promising solution for siRNA delivery and had the potential in anti-tumor gene therapy.
Journal of Nanobiotechnology 04/2014; 12(1):13. · 5.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Since the availability of recombinant human growth hormone (rhGH) enabled the application of human growth hormone both in clinical and research use in the 1980s, millions of patients were prescribed a daily injection of rhGH, but noncompliance rates were high. To address the problem of noncompliance, numerous studies have been carried out, involving: sustained-release preparations, prolonged half-life derivatives, new injectors that cause less pain, and other noninvasive delivery methods such as intranasal, pulmonary and transdermal deliveries. Some accomplishments have been made and launched already, such as the Nutropin Depot(®) microsphere and injectors (Zomajet(®), Serojet(®), and NordiFlex(®)). Here, we provide a review of the different technologies and illustrate the key points of these studies to achieve an improved rhGH product.
International Journal of Nanomedicine 01/2014; 9:3527-3538. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Poly(lactic-co-glycolic acid) (PLGA) and/or poly(lactic-acid) (PLA) microspheres are important drug delivery systems. This study investigated eye biocompatibility and safety of PLGA/PLA microspheres through intravitreal injection in rabbits. Normal New Zealand rabbits were randomly selected and received intravitreal administration of different doses (low, medium, or high) of PLGA/PLA microspheres and erythropoietin-loaded PLGA/PLA microspheres. The animals were clinically examined and sacrificed at 1, 2, 4, 8, and 12 weeks postadministration, and retinal tissues were prepared for analysis. Retinal reactions to the microspheres were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end staining and glial fibrillary acidic protein immunohistochemistry. Retinal structure changes were assessed by hematoxylin and eosin staining and transmission electron microscopy. Finally, retinal function influences were explored by the electroretinography test. Terminal deoxynucleotidyl transferase-mediated dUTP nick end staining revealed no apoptotic cells in the injected retinas; immunohistochemistry did not detect any increased glial fibrillary acidic protein expression. Hematoxylin and eosin staining and transmission electron microscopy revealed no micro- or ultrastructure changes in the retinas at different time points postintravitreal injection. The electroretinography test showed no significant influence of scotopic or photopic amplitudes. The results demonstrated that PLGA/PLA microspheres did not cause retinal histological changes or functional damage and were biocompatible and safe enough for intravitreal injection in rabbits for controlled drug delivery.
International Journal of Nanomedicine 01/2014; 9:3057-68. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aim: The nonviral carrier system based on the triblock copolymer PEG-PCL-DEX (PPD) and protamine was developed for nucleic acid delivery. Materials & methods: Self-assembly occurred in the PEG continuous phase to form 'dextran-interior' polymersomes. siRNA can be condensed by protamine and encapsulated into PPD polymersomes in order to form the PPD-protamine siRNA nanoparticles by thermodynamically preferential partition between the PEG continuous phase and the dextran cavity. Results: This system can package siRNA into PPD polymersomes to form 145.2 ± 8.02-nm (± standard deviation) nanoparticles, and the ζ-potential can be reduced to approximately 0 mV. PPD-protamine siRNA nanoparticles achieved cellular uptake of siRNA in SMMC-7721 cells with negligible cytotoxicity, and the GL3 gene expression can be reduced to 61.73 ± 6.25%. A biodistribution study of nanoparticles suggested that the PPD-protamine siRNA nanoparticles mainly accumulated in liver. Conclusion: All of these results suggest that PPD-protamine carriers may offer a promising gene delivery strategy for the treatment of liver-related disease. Original submitted 14 September 2012; Revised submitted 21 March 2013.
[Show abstract][Hide abstract] ABSTRACT: Mass production of high-quality graphene nanosheets (GNs) is essential for practical applications. We report that oxidation of graphite by low concentration KMnO4 at relatively high temperature (60°C) leads to edge-selectively oxidized graphite (EOG) which preserves the high crystalline graphitic structure on its basal planes while the edges are functionalized by oxygen-containing groups. Long-chain tetradecyl-ammonium salt (C14N(+)) could be spontaneously intercalated into EOG to form intercalated EOG-C14N(+) compounds. Gentle and short-time sonication of EOG-C14N(+) in toluene can full exfoliate EOG into edge-oxidized graphene nanosheets (EOGNs) with concentration of 0.67 mg/ml, monolayer population up to 90% and lateral size from 1 μm to >100 μm. The EOG and EOGN films show excellent electrical conductance, which is far superior to their graphene oxide (GO) counterparts. Our method provides an efficient way to produce high-quality GNs, and the resultant EOG also can be directly used for production of multifunctional materials and devices.
[Show abstract][Hide abstract] ABSTRACT: One of the most challenging problems in the development of protein pharmaceuticals is to deal with stabilities of proteins due to its complicated structures. This study aims to develop a novel approach to stabilize and encapsulate proteins into dextran nanoparticles without contacting the interface between the aqueous phase and the organic phase. The bovine serum albumin, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), beta-galactosidase, and myoglobin were selected as model proteins. The proteins were added into an aqueous solution containing the dextran and polyethylene glycol, and then encapsulated into dextran nanoparticles by aqueous-aqueous freezing-induced phase separation. The encapsulation efficiency and recovery of dextran nanoparticles were determined. The dextran nanoparticles loaded with proteins were characterized by scanning electron microscopy and particle size analysis. The protein aggregation was determined by size-exclusion chromatography-high-performance chromatography, and the bioactivity of proteins recovered during formulation steps was determined. The bioactivity of GM-CSF, G-CSF, and beta-galactosidase were examined by the proliferation of TF-1 cell, NSF-60 cell, and ortho-nitrophenyl-beta-galactoside assay, respectively. The results of bioactivity recovered show that this novel dextran nanoparticle can preserve the protein's bioactivity during the preparation process. LysoSensorTM Yellow/Blue dextran, a pH-sensitive indicator with fluorescence excited at two channels, was encapsulated into dextran nanoparticles to investigate the ability of dextran nanoparticles to resist the acidic microenvironment (pH < 2.5). The result shows that the dextran nanoparticles attenuate the acidic microenvironment in the poly (lactic-co-glycolic acid) microsphere by means of the dilution effect. These novel dextran nanoparticles provided an appealing approach to stabilize the delicate proteins for administration.
Nanoscale Research Letters 04/2013; 8(1):197. · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, we formulated a rIL-2 loaded sustained-release dextran/PLGA-PLA core/shell microsphere, mimicking the paracrine mechanisms of cytokine action, to investigate its local antitumor efficacy. The presented microspheres were formed in two steps: rIL-2 was firstly loaded into dextran particles to keep its bioactivity by a unique method of stabilizing aqueous-aqueous "emulsion"; subsequently, the particles were encapsulated into Poly (DL-lactide-co-glycolide)/Polylactic acid (PLGA/PLA). A stable sustained release behavior in vitro was achieved for a period of about 25 days. In the subcutaneous colon carcinoma BALB/c mice models, a single dose of microspheres was introtumorally administrated and compared with multiple doses of rIL-2 solution to investigate the long acting effect of microspheres on tumor. The animal experiments showed the local efficacy at tumor site mediated by rIL-2 from a single dose of microspheres was better than that of multiple rIL-2 solution injections. Based on the experimental results, we conclude that rlL-2 loaded sustained-release dextran/PLGA-PLA core/shell microspheres represent a promising approach for local cancer treatment in animals.
International Journal of Pharmaceutics 04/2013; · 3.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized clinically by memory and cognitive dysfunction. Unfortunately, there is no effective therapeutic method for AD treatment or ways to halt disease progression. Many mechanisms are involved in the disease, including genes mutation and protein dysfunction. RNA interference (RNAi) technology may potentially be able to control AD. It can inhibit the protein expression of specific genes by activating a sequence-specific RNA degradation process. This is a powerful tool with which to study gene function, investigate the mechanism of the disease, and validate drug targets. In this review, we highlight the advances in RNAi technology in the investigation and treatment of AD.
Drug Design, Development and Therapy 01/2013; 7:117-25. · 3.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Surgical tumor resection is the main treatment for tumors however the treatment process often results in massive bleeding and tumor cell residue. The main aim of this research was to address problems such as bleeding, systemic chemotherapy side effects while enhancing quality of life, and increasing drug concentrations at the tumor site by developing a novel formulation with local long-term efficacy for treatment of tumors and to stop bleeding.
5-Fluorouracil (5-FU) was suspended in an ethyl acetate solution of poly D,L-lactide-co-glycolic acid (PLGA) and a vacuum drying method was applied. The hemostatic gelatin sponge loaded with 5-FU was prepared by absorption of the suspension. The in vitro and in vivo characteristics of the hemostatic gelatin sponge loaded with 5-FU (5-FU-HAGS) were investigated.
5-FU-HAGS (hemostatic absorbable gelatin sponge loaded with 5-fluorouracil) was successfully produced with controlled release of the content and was reproducibly suitable for local tumor treatment as an implant to stop bleeding. The encapsulation efficiency of 5-FU-HAGS was above 98%. The in vitro 5-FU release kinetic profile matched a near zero-order equation for 20 days. The in vivo 5-FU plasma concentration was at a more stable level than when 5-FU solution was administered by subcutaneous injection. Bleeding can be stopped more effectively by coating a piece of blank gelatin sponge. The survival ratio of tumor-bearing mice using a 5-FU-HAGS subcutaneous implant was higher when compared to mice given a subcutaneous injection of 5-FU solution.
The 5-FU-HAGS system is a potential and effective way of enhancing the survival ratio and improving the quality of life of tumor-bearing mice.
International Journal of Nanomedicine 01/2013; 8:1499-506. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An increasing number of drugs are needing improved formulations to optimize patient compliance because of their short half-lives in blood. Sustained-release formulations of drugs are often required for long-term efficacy, and microspheres are among the most popular ones. When drugs are encapsulated into microsphere formulations, different methods of preparation need to be used according to specific clinical requirements and the differing physicochemical characteristics of individual drugs. In this work, we developed a novel method for sustained-release drug delivery using a water-in-oil-in-hydrophilic oil-in-water (w/o/oh/w) emulsion to encapsulate a drug into poly(lactic-co-glycolic acid) (PLGA) microspheres. Different effects were achieved by varying the proportions and concentrations of hydrophilic oil and PLGA. Scanning electron and optical microscopic images showed the surfaces of the microspheres to be smooth and that their morphology was spherical. Microspheres prepared using the w/o/oh/w emulsion were able to load protein efficiently and had sustained-release properties. These results indicate that the above-mentioned method might be useful for developing sustained-release microsphere formulations in the future.
International Journal of Nanomedicine 01/2013; 8:2433-41. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microneedles were first conceptualized for drug delivery many decades ago, overcoming the shortages and preserving the advantages of hypodermic needle and conventional transdermal drug-delivery systems to some extent. Dissolving and biodegradable microneedle technologies have been used for transdermal sustained deliveries of different drugs and vaccines. This review describes microneedle geometry and the representative dissolving and biodegradable microneedle delivery methods via the skin, followed by the fabricating methods. Finally, this review puts forward some perspectives that require further investigation.
Drug Design, Development and Therapy 01/2013; 7:945-952. · 3.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Encapsulating exogenous proteins into a nanosized particulate system for delivery into cells is a great challenge. To address this issue, we developed a novel nanoparticle delivery method that differs from the nanoparticles reported to date because its core was composed of cross-linked dextran glassy nanoparticles which had pH in endosome-responsive environment and the protein was loaded in the core of cross-linked dextran glassy nanoparticles.
In this study, dextran in a poly(ethylene glycol) aqueous two-phase system created a different chemical environment in which proteins were encapsulated very efficiently (84.3% and 89.6% for enhanced green fluorescent protein and bovine serum albumin, respectively) by thermodynamically favored partition. The structures of the nanoparticles were confirmed by confocal laser scanning microscopy and scanning electron microscopy.
The nanoparticles had a normal size distribution and a mean diameter of 186 nm. MTT assays showed that the nanoparticles were nontoxic up to a concentration of 2000 μg/mL in human hepatocarcinoma cell line SMMC-7721, HeLa, and BRL-3A cells. Of note, confocal laser scanning microscopy studies showed that nanoparticles loaded with fluorescein isothiocyanate-bovine serum albumin were efficiently delivered and released proteins into the cytoplasm of HeLa cells. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling assays showed that nanoparticles with a functional protein (apoptin) efficiently induced significant tumor cell apoptosis, which was confirmed by DAPI staining.
Our findings indicate that these nanoparticles meet the high demands for delivering protein medicines and have great potential in protein therapy.
International Journal of Nanomedicine 01/2013; 8:3405-14. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Parkinson's disease (PD) is the second-most common age-dependent neurodegenerative disorder and is caused by severe degeneration of dopaminergic neurons in the substantia nigra pars compacta. Unfortunately, current treatment only targets symptoms and involves dopamine replacement therapy, which does not counteract progressive degeneration. MicroRNAs (miRNAs) are a class of small RNA molecules implicated in post-transcriptional regulation of gene expression during development. Recent studies show that miRNAs are playing an important role in the pathophysiology of PD. miRNA-based therapy is a powerful tool with which to study gene function, investigate the mechanism of the disease, and validate drug targets. In this review, we focus on the recent advances of the use of miRNAs in the pathogenesis of PD.
Drug Design, Development and Therapy 01/2013; 7:1103-1113. · 3.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies.
International Journal of Nanomedicine 01/2013; 8:1111-20. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Parkinson's disease is a neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra. The dopamine precursor, levodopa, remains the most effective and common treatment for this disorder. However, long-term administration of levodopa is known to induce characteristic dyskinesia, and molecular mechanisms underlying dyskinesia are poorly understood.
In this study, we investigated the effect of 6-hydroxydopamine lesions in dopaminergic neurons and chronic treatment with levodopa on expression of G protein-coupled receptor kinase 6 and â-arrestin-1, two key regulators of G protein-coupled receptors, in the rat striatum.
We found that a unilateral 6-hydroxydopamine lesion reduced expression of G protein-coupled receptor kinase 6 and â-arrestin-1 protein in the lesioned striatum. Reduction of these two proteins persisted in 6-hydroxydopamine-lesioned rats on chronic levodopa treatment for 23 days. In addition, coadministration of the N-methyl-D-aspartate receptor antagonist, MK-801, and levodopa reversed the reduction of G protein-coupled receptor kinase 6 and â-arrestin-1 in the striatum. MK-801 also attenuated levodopa-induced dyskinetic behavior.
These data indicate that G protein-coupled receptor kinase 6 and â-arrestin-1 in striatal neurons are sensitive to dopamine depletion and are downregulated in rats with Parkinson's disease and in levodopa-treated rats with the disease. This downregulation seems to require activation of N-methyl-D-aspartate glutamate receptors.
Clinical Interventions in Aging 01/2013; 8:347-52. · 2.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: P-glycoprotein is one of the earliest known multidrug transporters and plays an important role in resistance to chemotherapeutic drugs. In this study, we detected levels of P-glycoprotein and its mRNA expression in a rat brain model of medically intractable epilepsy established by amygdala kindling and drug selection. We investigated whether inhibition of P-glycoprotein affects the concentration of antiepileptic drugs in cortical extracellular fluid. We found that levels of P-glycoprotein and its mRNA expression were upregulated in epileptic cerebral tissue compared with cerebral tissue from normal rats. The concentrations of two antiepileptic drugs, carbamazepine and phenytoin, were very low in the cortical extracellular fluid of rats with medically intractable epilepsy, and were restored after blockade of P-glycoprotein by verapamil. These results show that increased P-glycoprotein levels alter the ability of carbamazepine and phenytoin to penetrate the blood-brain barrier and reduce the concentrations of these agents in extracellular cortical fluid. High P-glycoprotein levels may be involved in resistance to antiepileptic drugs in medically intractable epilepsy.
Drug Design, Development and Therapy 01/2013; 7:1447-1454. · 3.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Exenatide has been widely used for the treatment of type 2 diabetes mellitus. However, its short plasma half-life of 2.4 hours has limited its clinical application. The exenatide products on the market, twice-daily Byetta™ and once-weekly Bydureon™ (both Amylin Pharmaceuticals, San Diego, CA, USA), are still not perfect. Many researchers have attempted to prolong the acting time of exenatide by preparing sustained-release dosage forms, modifying its structure, gene therapies, and other means. This review summarizes recent advances in long-acting exenatide preparations.
Drug Design, Development and Therapy 01/2013; 7:963-970. · 3.49 Impact Factor