生物可降解微球作为HPV-E7蛋白免疫佐剂的研究

目的：对聚乳酸聚羟基乙酸（PGLA）作为疫苗运输载体进行免疫学评价。方法：用复乳法制备PLGA微球,通过表面吸附人乳头状瘤病毒（HPV）E7蛋白制备成聚乳酸聚羟基乙酸（PGLA）微球,考察粒径分布情况及体外释放水平,通过皮下免疫注射途径免疫C57BL/6小鼠,用间接ELISA法检测免疫鼠血清中的抗体水平,由此评价PLGA微球疫苗运输载体的佐剂效应。。结果：复乳法制备的PLGA微球表面光滑,大小均匀,包封率20.1%,注射小鼠6周后（第2周加强免疫1次）,微球疫苗诱导产生的IgG1抗体水平较同剂量的铝佐剂组和溴化二甲基双十八胺（DDA）组明显升高,（平均滴度分别为3805、1270、2262）;微球疫苗诱导产生IgG2b的抗体水平明显高于铝佐剂组,略低于DDA组,（平均滴度分别为1131、475、2653）而IgG2c的抗体量高于铝佐剂组和DDA组（平均滴度分别为150、36、106）。结论：人乳头状瘤病毒E7蛋白聚乳酸羟基乙酸微球作为疫苗输送体系可以明显的提高抗原的免疫原性。     

生物可降解微球作为乙型肝炎基因免疫佐剂的研究

探讨生物可降解微球对基因免疫的增强作用。采用有机溶剂蒸发法制备聚乳酸聚乙醇酸共聚 物（ＰＬＧＡ）微球,构建含有乙型肝炎病毒表面抗原Ｓ基因的ｐＲＣ－ＣＭＶ真核表达载体,用微球与基因 载体共孵育法制备其混合物。肌肉注射免疫Ｂａｌｂ／ｃ小鼠。结果表明：微球注射组的血清抗体滴度达到 ｌ：１６００,其效果与乙型肝炎病毒表面抗原加铝佐剂注射组相近,而裸ＤＮＡ注射组没有反应。说明了 生物可降解微球可显著的提高基因免疫的免疫反应。     

PLGA纳米/微球作为核酸载体的研究进展

生物可降解材料[poly(lactide-co-glycolide acid), PLGA]颗粒在持续释放和定位递送各种药剂包括核酸有很大的研究和应用价值。本文综述了PLGA作为核酸载体的制备及其用于基因载体和疫苗佐剂的研究。     

PLGA微球复合明胶组织工程支架缓释蛋白药物的研究

目的：研究PLGA微球复合明胶支架对蛋白药物的释放影响。方法：将模型蛋白BSA通过复乳法制备成缓释PLGA微球,然后将微球埋置于明胶支架中,形成担载蛋白的PLGA微球复合明胶组织工程支架。考察复合支架体外蛋白释放行为,并用MicroBCA法定量测定释放的BSA量,采用β-半乳糖苷酶催化ONPG的方法检测制备前后蛋白的活性,并与不含PLGA微球直接担载蛋白的支架做对照。结果：PLGA微球复合支架蛋白的包封率能达到73．2％,其中第一天释放20％,对蛋白活性的保持达到70％以上。结论：微球复合明胶支架可以改善一般组织工程支架蛋白药物的突释,提高蛋白药物在制剂,贮存,释放过程中的稳定性。     

左旋多巴甲酯缓释微球的研究

目的：由于长期服用左旋多巴治疗帕金森病,其药物浓度波动刺激易引起异动症,本实验旨在制备突释小,药物释放浓度稳定的左旋多巴甲酯微球制剂。方法：将左旋多巴甲酯用复乳法包裹于PLGA微球内,采用C18反相色谱研究药物包封率和体外释放行为。结果：通过调节药物浓度和不同高分子组合筛选出突释小,包封率高且缓慢释放的处方。结论：左旋多巴甲酯包裹于PLGA能实现理想的缓释效果,降低药物浓度波动,为后期药效学实验提供基础。     

左旋多巴甲酯缓释微球的研究

目的:由于长期服用左旋多巴治疗帕金森病,其药物浓度波动刺激易引起异动症,本实验旨在制备突释小,药物释放浓度稳定的左旋多巴甲酯微球制剂。方法:将左旋多巴甲酯用复乳法包裹于PLGA微球内,采用C18反相色谱研究药物包封率和体外释放行为。结果:通过调节药物浓度和不同高分子组合筛选出突释小,包封率高且缓慢释放的处方。结论:左旋多巴甲酯包裹于PLGA能实现理想的缓释效果,降低药物浓度波动,为后期药效学实验提供基础。     

包裹于PLGA微球中用于蛋白控释的多糖纳米颗粒

目的:研究包裹在PLGA微球中的多糖纳米颗粒在保护蛋白稳定性和改善药物体外释放行为方面的作用。方法:将模型药物BSA用低温诱导相分离方法担载于多糖纳米颗粒之中,后将其用水包油包固复乳法包裹于PLGA微球内。应用体积排阻色谱(SEC-HPLC)和红外色谱(FTIR)表征蛋白的稳定性,而且也研究了样品的体外释放行为。结果:这种方法能够很好的保护蛋白的稳定性,保持蛋白结构在制备过程中不会改变,而且改善了体外释放行为,减少了突释。结论:多糖纳米颗粒结合PLGA微球能够提供一种有效的解决蛋白控释的途径。     

纳米丝素蛋白微球的制备及性能研究

以家蚕丝素蛋白为原料,基于丝素自组装理论,通过酶解-干燥-溶解法制备不同尺寸的丝素蛋白微球,制备出的微球具有良好的水不溶性和稳定的分散性。对微球的形貌和结构表征结果表明,用该方法制备的丝素蛋白微球为纳米微球,当酶的添加量为2%且蛋白自组装时间为4 h时,丝素蛋白微球的平均粒径最小,仅为(32±11)nm。红外光谱(FT-IR)和X射线衍射(XRD)结果显示,微球中β-折叠结构的多少决定了微球晶体的大小,β-折叠越多,微球中晶体的体积越大。通过调控丝素蛋白自组装过程,可以制备平均粒径在30～140 nm之间的纳米丝素蛋白微球,且不引入任何有机溶剂和无机溶剂,制备过程绿色环保,制备出的丝素蛋白微球安全无毒。     

影响PLGA微球包封率和粒径相关因素研究进展

聚乳酸乙醇酸共聚物(PLGA)是一种可生物降解的高分子聚合物,具有良好的生物相容性,其降解产物为乳酸和乙醇酸,是机体正常代谢的中间产物,最终可分解为二氧化碳和水,并分别经肺和肾脏排出体外,对人体不产生危害,所以PLGA在微球制剂的制备中常作为首选载体。近年来PLGA微球制剂在医药领域有着飞跃发展,尤其是在抗肿瘤、免疫疫苗、蛋白给药、基因治疗、诊断试剂和细胞支架等方面显现出很大优势。而且已有许多PLGA微球获得美国FDA批准上市,临床应用也有令人满意的效果,未见报道有严重的不良反应。但现阶段国内生产的PLGA缓释微球的质量还有很多不足之处如微球粒径偏大、包封率和载药量偏低、突释过大等,有待进一步提高和改进。本文将综述在制备包裹水溶性药物的PLGA微球过程中相关因素如药物本身理化性质、制备方法、PLGA结构特点、有机溶剂等对微球粒径、包封率的影响,以期为提高以PLGA为药物载体的药效奠定良好的理论基础。     

Design of Methylprednisolone Biodegradable Microspheres Intended for Intra-articular Administration

This study aimed to design methyprednisolone (MP)-loaded poly(d,l lactide-co-glycolide) (PLGA) microspheres (MS) intended for intra-articular administration. MP was encapsulated in four different types of PLGA by using an S/O/W technique. The effects of β-irradiation at the dose of 25 kGy were evaluated on the chemical and physicochemical properties of MS and the drug release profiles. The S/O/W technique with hydroxypropylmethylcellulose (HPMC) as surfactant allowed obtaining MS in the tolerability size (7–50 μm) for intra-articular administration. The MP encapsulation efficiency ranged 56–60%. HPMC traces were evidenced in the loaded and placebo MS by attenuated total reflectance Fourier transform infrared spectroscopy. MS made of the capped PLGA DL5050 2M (MS 2M) and uncapped PLGA DL5050 3A (MS 3A) prolonged the release of MP over a 2- to 3-month period with a triphasic (burst release–dormant period–second release pulse) and biphasic release pattern, respectively. The β-irradiation did not significantly alter the morphology, chemical, and physicochemical properties of MS. The only variation was evidenced in the drug release for MS 2M in term of shorting of the dormant period. The minimal variations in the properties of irradiated PLGA MS, which are in disagreement with literature data, may be attributed to a radioprotecting effect exerted by HPMC.     

降钙素葡聚糖颗粒缓释微球的研究

目的：降钙素（一个由32个氨基酸组成的多肽）是治疗骨质疏松的首选药之一。降钙索的劣势是其半衰期过短,需要一天一次注射给药,本实验旨在制备突释小,药物释放浓度稳定的降钙素微球制剂。方法：制备降钙素羧酸葡聚糖颗粒和降钙素硫酸葡聚糖颗粒组合物,分别将其包裹于PLGA微球内,制备成降钙素组合微球,采用C18反相色谱柱研究药物的包封率和体外释放行为。结果：所制得的降钙素葡聚糖颗粒缓释微球体外释放一个月,释放曲线比较完美,接近零级释放。结论：本研究制得的降钙素葡聚糖颗粒缓释组合微球能实现理想的体外缓释效果,为后期药动学实验提供基础。     

重组人粒细胞集落刺激因子缓释微球的研究

目的：研究固体／油／水法制备重组人粒细胞集落刺激因子缓释微球,为开发其缓释剂型进行初步研究。方法：以聚乳酸．聚羟乙酸共聚物（PLGA）为载体材料：用固体／油／水法和水／油／水法制备载rhG-CSF缓释微球;考察粒径大小、外观、包封率等理化性质;用MieroBCA法考察微球的体外释药特性及影响因素;用SEC-HPLC和MTT比色法初步评价了微球制备工艺过程对rhG-CSF稳定性的影响。结果：两种方法制得的微球形态圆整、分散性良好,包封率均超过80％。固／油／水法制得的微球体外释放在2周内可超过90％,而水／油／水法制得的微球在相同的时间内仅释放30％。对于固／油／水法制备过程,SEC-HPLC法测定蛋白无明显聚集体出现,MTT法测定蛋白活性无明显损失。结论：实验证明了固／油／水法制备的PLGA微球可以实现2周以上的体外缓释。     

Polymeric Microspheres as Protein Transduction Reagents

Discovering the function of an unknown protein, particularly one with neither structural nor functional correlates, is a daunting task. Interaction analyses determine binding partners, whereas DNA transfection, either transient or stable, leads to intracellular expression, though not necessarily at physiologically relevant levels. In theory, direct intracellular protein delivery (protein transduction) provides a conceptually simpler alternative, but in practice the approach is problematic. Domains such as HIV TAT protein are valuable, but their effectiveness is protein specific. Similarly, the delivery of intact proteins via endocytic pathways (e.g. using liposomes) is problematic for functional analysis because of the potential for protein degradation in the endosomes/lysosomes. Consequently, recent reports that microspheres can deliver bio-cargoes into cells via a non-endocytic, energy-independent pathway offer an exciting and promising alternative for in vitro delivery of functional protein. In order for such promise to be fully exploited, microspheres are required that (i) are stably linked to proteins, (ii) can deliver those proteins with good efficiency, (iii) release functional protein once inside the cells, and (iv) permit concomitant tracking. Herein, we report the application of microspheres to successfully address all of these criteria simultaneously, for the first time. After cellular uptake, protein release was autocatalyzed by the reducing cytoplasmic environment. Outside of cells, the covalent microsphere–protein linkage was stable for ≥90 h at 37 °C. Using conservative methods of estimation, 74.3% ± 5.6% of cells were shown to take up these microspheres after 24 h of incubation, with the whole process of delivery and intracellular protein release occurring within 36 h. Intended for in vitro functional protein research, this approach will enable study of the consequences of protein delivery at physiologically relevant levels, without recourse to nucleic acids, and offers a useful alternative to commercial protein transfection reagents such as Chariot™. We also provide clear immunostaining evidence to resolve residual controversy surrounding FACS-based assessment of microsphere uptake.Many proteomic techniques can be used to build a picture of a protein with unknown function, but eventually the individual protein''s activity must be studied. Traditional transfection of encoding DNA permits intracellular expression, but often at uncontrolled, nonphysiological levels. Moreover, DNA transfection can neither deliver protein–inhibitor complexes nor readily deliver multiple proteins in a single experiment and thus exploit knowledge from proteomic protein–protein interaction analyses. In contrast, a truly generic protein transduction reagent could theoretically address all possibilities. We believe that polymeric microspheres could fulfill this role, and we have recently synthesized and characterized dual-functionalized, bio-compatible microspheres that permit intracellular tracking (1). Herein, we now report the development of those microspheres into a protein transduction reagent that can carry protein stably, deliver it efficiently to cells, release the protein in the cytoplasm, and concurrently permit fluorescent imaging of transduced cells.Phagocytosis of microspheres was first observed over 30 years ago (2). Perhaps more unexpectedly, uptake of polystyrene microspheres has recently been reported in many other, nonphagocytic cell types, some of which are traditionally considered to be resistant to DNA transfection and/or protein transduction. For example, microspheres are taken up readily by primary immune cells (3), embryonic stem cells (4), human neural stem cells (5), differentiating mouse neural stem cells (5), and several nonphagocytic cell lines (3, 6, 7). In all instances, the reported efficiency of cellular uptake is high, with “beadfection” of up to 90% of cells being typical (4, 5, 8). No additional reagents aside from the microspheres themselves are required in order to promote cellular uptake, and critically, no toxicity has been observed in any of the cell types beadfected, including HEK293T and L929 cells 2 days after beadfection (8), E14g2a embryonic stem cells 3 days after beadfection (4), and mouse and human neural stem cells 30 days after beadfection (5). In the latter case, the microspheres did not have any deleterious effect on the differentiation of human neural stem cells 30 days after beadfection (5).The mechanism of microsphere entry is also nontoxic, and compelling evidence has been published recently that polystyrene-based microspheres (from 0.2 μm to as large as 2 μm) enter cells via a non-endocytosis, energy-independent mechanism (8). Although unusual, such a mechanism is consistent with claims for the commercial reagent Chariot™ (9). Interestingly, a non-endocytic, energy-independent mechanism has also been reported for the entry of rhenium cluster/polymer hybrid particles into HeLa cells (10). Failure of the microspheres to be endocytosed, at least via a clathrin-dependent mechanism, is perhaps to be predicted, as their diameter considerably exceeds that of clathrin-coated vesicles (typically 100 nm). Bradley and co-workers (8) propose that the entry mechanism for polystyrene-based microspheres is one of passive diffusion in which the microsphere interacts with the membrane, anchors, and, after membrane reorganization, enters the cell, resulting in direct cytoplasmic localization.For functional analysis following transduction, the avoidance of endocytosis or phagocytosis is particularly relevant, as endocytosed particles are destined for endosomes and then, normally, for the lysosomes. The lowered pH of the endosome and, more seriously, the acidic and hydrolytic environment of the lysosome risk disruption of the protein structure and/or function. In contrast, for vaccine delivery (where liposomes can be employed), such exposure is advantageous because protein breakdown forms an essential part of antigen presentation. The potential for protein breakdown in endosomes is also irrelevant for the delivery of protein/peptide drugs such as insulin (for which microencapsulation has proven effective for long-term controlled drug release (11, 12)), as these drugs typically function in the extracellular environment, often exerting their effects by binding to membrane-bound receptors. Thus, although vehicles such as liposomes and nanoparticles are employed both extensively and successfully as drug and vaccine delivery vectors in vivo (13–16), they are far from ideal for studying the biological effect of a delivered protein in vitro. Colloidal particles are also endocytosed (17), and therefore these delivery vehicles may present similar disadvantages.Traditionally, protein transduction domains such as HIV TAT (18–20) or other cell-penetrating peptides (21–23) are used to deliver proteins to cells. Whereas positively charged peptides such as TAT are thought to enter the cells via macropinocytosis (reviewed in Ref. 24), a recent publication suggests that at least some cell-penetrating peptide/bio-cargo complexes (siRNA) are endocytosed (25). Here, although the cargoes avoid the lysosomes, acidification of the endosome is required for endosomal escape of the delivered cargo, and indeed, acidification appears to be a recurring requirement for endosomal escape of biomolecular cargoes using cell-penetrating peptides (reviewed in Ref. 24). Consequently, cell-penetrating peptides are unlikely to become generic tools for functional protein delivery.In contrast, the recent demonstrations that polystyrene microspheres can carry a variety of molecular cargoes with them into the cytoplasm (4, 5, 7, 26, 27) make them particularly exciting as potential vectors for delivering functional proteins and/or protein complexes. β-Galactosidase retains its activity when delivered via this route (7), confirming the potential of microspheres to act as generic protein-delivery vehicles. However, delivered proteins have to date remained tethered to the microspheres, and thus existing studies are limited to proteins that are active in the cytoplasm and, critically, retain their activity when immobilized on polystyrene. For the broad-based study of protein function, the subsequent release of the delivered protein within the cell is desirable.An ideal technology would deliver any protein to any cell type and release that protein in the cell, where it could undertake its normal activity. Here we report the first example of such a microsphere-based approach. Protein is delivered on microspheres and then released in the cell by the reducing cytoplasmic environment. This release is mediated by a linker that attaches the protein stably and covalently to the microspheres in vitro but intracellularly is cleaved over a period of hours. It has already been shown that microspheres are taken up with high efficiency by a range of cell types and can carry a variety of cargoes. Because the chemistry of the linker described herein is amenable to linkage with any molecule containing a free amine moiety, the technology provides a new generic platform for in vitro, cell-based delivery of individual proteins, protein complexes, protein mixtures, or other amino-functionalized molecules.     

利用生物可降解海藻酸钙微球保护苏云金杆菌晶体与芽胞免受紫外线降解

采用基于注射挤压器的液滴形成技术制备包裹了苏云金杆菌晶体和芽胞的海藻酸钙凝胶微球.通过调节该装置的活塞重量和空气压力,获得了平均直径为20μm的微球.SDS-PAGE分析与平板菌落涂布实验表明,凝胶微球可有效减少紫外线对苏云金杆菌晶体和芽胞的损伤作用.利用小菜蛾进行的毒力生测发现,凝胶微球可有效防止紫外线引起的晶体和芽胞杀虫毒力的下降.本研究的液滴形成技术也可适用于其它微球包裹过程.     

细胞因子作为DNA疫苗佐剂的研究进展

细胞因子是机体细胞(主要指免疫细胞)产生的一类具有广泛生物学活性的异质性肽类调节因子,在体内能激活免疫活性细胞,对免疫应答的产生和调节有重要作用。近年来,大量研究表明细胞因子可作为DNA疫苗佐剂来增强疫苗的免疫效果。简要综述了细胞因子作为DNA疫苗免疫佐剂的研究进展。