Recombinant L7/L12 protein entrapping PLGA (poly lactide-co-glycolide) micro particles protect BALB/c mice against the virulent B. abortus 544 infection

Brucella abortus is the etiologic agent of Brucellosis, a zoonotic infection affecting a wide range of animals. It is a highly infectious disease of pandemic potential reporting over 500,000 new human cases annually. Till date, there is no reported vaccine for humans and the available animal vaccines are unsafe, therefore a safe and effective subunit vaccine is highly sought for. In this study, we have evaluated rL7/L12 protein encapsulated in microparticles of PLGA (85:15), a biocompatible and biodegradable polymer approved by FDA for human use. In this work, BALB/c mice have been immunized with rL7/L12 entrapped in microparticles in a prime-boost regimen. Further, evaluation of the immunogenicity of the formulation showed that the IgG antibody titre reached a maxima of 2.2 × 10⁵ (p value 0.0001 v/s control) after the injection of the booster dose. A mixed IgG isotype profile (IgG1/IgG2a) indicated the stimulation of both the cellular as well as humoral immunity which has increased parallely and gradually since the first immunization. High levels of IFN-γ, 815 ± 55 pg/ml were recorded depicting an optimal elicitation of the cellular wing of immunity leading to clearance of splenic bacteria upto 1.69 log units.     

乳酸-乙醇酸共聚物载药复合纤维制备及其释药行为研究

乳酸-乙醇酸共聚物(PLGA)复合纤维具有良好的生物相容性和生物可降解性,且降解速率可由相对分子质量和共聚物组成来调控.采用同轴静电纺丝法制备以PLGA为壳层材料、聚乙烯基吡咯烷酮(PVP)为内芯材料的复合纤维,研究两种模型药物(5-氟尿嘧啶和硝苯地平)在同轴复合纤维载体中的药物释放行为,并用扫描、透射电镜观察复合纤维的形貌与结构,用紫外分光光度计测量载药量和累积释放率.实验结果表明,通过改变芯、壳纺丝液浓度、PLGA相对分子质量以及共聚物中LA和GA的组成比,可制得具有芯-壳结构且直径大小不同的复合纤维.采用相同电纺丝条件,可以将不同药物以相同载药量包覆于复合纤维中,但药物的释放行为不相同.     

Poly(D,L-lactide-co-glycolide) encapsulated poly(vinyl alcohol) hydrogel as a drug delivery system

Purpose. The efficiency of encapsulation of water-soluble drugs in biodegradable polymer is often low and occasionally these microcapsules are associated with high burst effect. The primary objective of this study is to develop a novel microencapsulation technique with high efficiency of encapsulation and low burst effect. Method. Pentamidine was used as a model drug in this study. Pentamidine/polyvinyl alcohol (PVA) hydrogel was prepared by freeze-thaw technique. Pentamidine loaded hydrogel was later microencapsulated in poly(lactide-co-glycolide) (PLGA) using solvent evaporation technique. The microcapsules were evaluated for the efficiency of encapsulation, particle size, surface morphology, thermal characteristic, and drug release. Results. Scanning Electron Microscope (SEM) studies revealed that the microcapsules were porous. The microcapsules were uniform in size and shape with the median size of the microcapsules ranging between 27 and 94 m. The samples containing 10% PLGA showed nearly three times increase in drug loading (18-53%) by increasing the hydrogel content from 0-6%. The overall drug release from the microencapsulated hydrogel, containing 3% and 6% PVA, respectively, was significantly lower than the control batches. Conclusions. The use of a crosslinked hydrogel such as PVA can significantly increase the drug loading of highly water-soluble drugs. In addition, incorporation of the PVA hydrogel significantly reduced the burst effect and overall dissolution of pentamidine.     

重组屋尘螨2类变应原疫苗免疫治疗小鼠过敏性气道炎症的研究

目的 观察以聚乳酸-羟基乙酸共聚物（PLGA）材料为佐剂制备的重组屋尘螨2类变应原（rDer p 2）纳米微粒疫苗（DEPN）对小鼠过敏性气道炎症的影响，并探讨其免疫治疗机 制。 方法 制备PLGA-rDer p 2纳米粒子并鉴定其特性。40只BALB/c小鼠随机分为5组，A组（对照组）均给予生理盐水（100 μl）。B、C、D和E组腹部皮下注射屋尘螨粗浸液（10 μg）免疫小鼠致敏，然后分别用PBS（100 μl）、2 mg 空白PLGA粒子（empty PLGA，EP）、100 μg rDer p 2、2 mg的DEPN纳米疫苗（载有100 μg rDer p 2）皮下注射进行免疫治疗，连续免疫治疗3 d，1次/d，各组用rDer p 2（50 μg）滴鼻激发，激发后第2天剖杀，收集支气管肺泡灌洗液（BALF）并对细胞进行总计数和分类计数；HE染色和PAS染色（Periodic Acid?鄄Schiff Stain）观察小鼠肺部组织炎症和支气管黏液分泌；用ELISA检测BALF和脾细胞培养上清的细胞因子（IL-4、 IFN-γ）和血清中变应原特异性IgG2a和IgE抗体浓度。 结果 B、C 组肺部呈明显的变态反应性炎症，D、E组变应原诱导的肺部嗜酸粒细胞浸润和黏液分泌比B、C 组显著减轻。BALF中的细胞总数B组比A组明显增多，分类细胞以中性和嗜酸粒细胞为主，超过50%。rDer p 2特异性IgE抗体水平，D组（0.93±0.04）和E组（0.77±0.10）均低于B组（1.14±0.10）（P＜0.01）；特异性IgG2a抗体水平，D组（1.02±0.01）和E组（1.17±0.46）均高于B组（0.14±0.01）（P＜0.01）。在BALF中，D组[（55.60±3.79） pg/ml]和E组[（48.60±4.50） pg/ml]IL-4水平均低于B组[（78.90±6.07） pg/ml]（P＜0.01）；IFN-γ水平E组[（68.50±2.87） pg/ml]显著高于B组[（27.30±3.51） pg/ml] （P＜0.01）。脾细胞上清的IL-4水平，D组[（56.3±4.85） pg/ml]和E组[（40.2±4.36） pg/ml]显著低于B组[（81.20±6.84） pg/ml] （P＜0.01）；IFN-γ水平，E组[（70.20±3.85） pg/ml]显著高于B组[（34.60±2.25） pg/ml] 。 结论 DEPN免疫治疗可抑制小鼠肺部过敏炎症，其机制可能与调节Th1/Th2平衡有关。     

PLGA nanoparticles for intravitreal peptide delivery: statistical optimization,characterization and toxicity evaluation

Abstract

Frequent intravitreal injections are currently used to overcome the ocular barriers and provide sufficient drug to the posterior eye segment. However, intravitreal injections have been associated with a number of complications and high treatment costs. To overcome these limitations, peptide-loaded poly(d,l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) were developed using the nanoprecipitation technique and were optimized via Box–Behnken Design (BBD) and Response Surface Methodology (RSM). Developed NPs were evaluated for potential toxicity and cell apoptosis using the zebrafish embryo toxicity (ZET) model with titanium dioxide NPs and ethanol (1% v/v) serving as positive controls. Developed NPs had a size of 75.6–153.8?nm, a polydispersity index between 0.11 and 0.25 and a zeta potential of ?9.4 to ?46.0?mV. Loaded peptide was found to be stable under various experimental conditions tested. BBD and RSM were validated through the characterization of optimized formulations. Survival and hatching rates of NP-treated zebrafish 0–144?h post-fertilization were found to be normal with no significant malformations. Cellular apoptosis studies also endorsed the non-cytotoxic nature of the NPs. The overall results indicate that optimized PLGA nanoparticles could be a promising platform for efficient peptide delivery to the posterior segment of the eye.     

Design of electrospun nanofibrous mats for osteogenic differentiation of mesenchymal stem cells

The clinical translation potential of mesenchymal stem cells (MSCs) in regenerative medicine has been greatly exploited. With the merits of high surface area to volume ratio, facile control of components, well retained topography, and the capacity to mimic the native extracellular matrix (ECM), nanofibers have received a great deal of attention as bone tissue engineering scaffolds. Electrospinning has been considered as an efficient approach for scale-up fabrication of nanofibrous materials. Electrospun nanofibers are capable of stimulating cell–matrix interaction to form a cell niche, directing cellular behavior, and promoting the MSCs adhesion and proliferation. In this review, we give a comprehensive literature survey on the mechanisms of electrospun nanofibers in supporting the MSCs differentiation. Specifically, the influences of biological and physical osteogenic inductive cues on the MSCs osteogenic differentiation are reviewed. Along with the significant advances in the field, current research challenges and future perspectives are also discussed.     

Characterization of a multi-epitope peptide with selective MHC-binding capabilities encapsulated in PLGA nanoparticles as a novel vaccine candidate against Toxoplasma gondii infection

No effective human vaccine against Toxoplasma gondii (T. gondii) has yet been developed; however, a protective vaccine using immunogenic peptides in a safe delivery vehicle system offers promise. Here, we employed bioinformatics to design a multimeric recombinant T. gondii vaccine using predicted T and B cell epitopes of SAG1, AMA1, ROP2, and GRA4 proteins based on their binding capabilities to common major histocompatibility complex (MHC) molecules. Furthermore, we encapsulated the expressed protein in poly lactic-co-glycolic acid (PLGA) nanoparticles as a delivery vehicle and also used alum as an adjuvant to determine the vaccine potency of this multimeric antigen. BALB/c mice were vaccinated and then challenged with T. gondii RH strain, and the survival rate and cytokine profiles were studied. Mice vaccinated with the multi-epitope-based vaccine, both with and without PLGA, had greater Th1 immune responses, survival rates, specific antibody titers, and IFN-γ and IL-2 levels than controls, while the alum-adsorbed vaccine stimulated a Th2-type humoral immune response.     

ENO1 monoclonal antibody inhibits invasion,proliferation and clone formation of cervical cancer cells

α-enolase (ENO1), highly expressing in cell membranes, cytoplasm and nuclei of cervical cancer and other tumors, acts as a plasminogen receptor and a glycolytic enzyme. ENO1 is found to be associated with tumorigenesis, invasion and migration, and proves to be an ideal target of tumor therapy. In this study, ENO1 monoclonal antibodies (ENO1mAb) was prepared to blockade ENO1 and the therapeutic role was observed in cervical cancer cells. First, ENO1mAb was prepared and screened by evaluating the inhibitory effect on migration and invasion of cervical cancer cells, which is supposed to block ENO1 expressed on cell membrane. Second, folic acid (FA) conjugated PLGA nanoparticles (FA-SS-PLGA) targeting tumor cells were prepared to mediate ENO1mAb entry into cells and its anti-tumor effects were investigated in vitro. We found that PLGA/FA-SS-PLGA nanoparticles-mediated ENO1mAb could antagonize the activity of ENO1 enzyme, significantly decreased the contents of lactic acid and pyruvate, and inhibited the proliferation, migration and clone formation of cervical cancer cells compared with the sham control (P < 0.05). In summary, ENO1mAb could specifically block ENO1 expressed on cell membrane and inhibit ENO1 glycolysis enzyme activity inside tumor cells, and plays a therapeutic role against cervical cancer cells. It suggests that ENO1mAb has promising anti-tumor effects.     

PLGA/PCL/nHA生物支架复合兔BMSCs体外培养的实验研究

目的:研究新型复合支架聚乳酸-聚乙醇酸/聚己内酯/纳米羟基磷灰石(PLGA/PCL/nHA)的生物相容性,探讨其作为细胞培养材料和骨组织工程支架的可行性.方法:将兔骨髓基质细胞(bone marrow stromal cells,BMSCs)接种于PLGA/PCL/nHA复合支架上,体外共同培养后,MTT法检测BMSC...     

载辛伐他汀PLGA/CPC复合材料的制备及表征

目的：制备具有药物缓释功能的聚乳酸聚羟基乙酸/磷酸钙骨水泥（PLGA/CPC）组织工程支架材料,评价其物理性能和药物释放性能。方法：通过调整高分子量、低分子量PLGA以及CPC这3种组分的比例将实验分为3组,采用冷冻干燥溶剂挥发技术合成复合材料,通过扫描电镜观察、模拟体液中pH值变化的结果筛选优化配比方案,最后将辛伐他汀载入制备载药复合支架材料,并用分光光度仪测定药物释放情况。结果：按质量比PLGA/CPC（2∶1）的配比所制备的复合支架材料平均孔径大小约120μm,且各孔之间有微孔相互贯通,8周时的pH值可稳定在6.5左右,同时该载药支架材料的缓释效果明显,体外药物释放达48d以上。结论：本实验所制备的载辛伐他汀PLGA/CPC复合材料,能满足骨组织工程支架材料的要求,可应用于剩余牙槽嵴骨吸收修复的研究。