Design, synthesis and in vitro evaluation of a novel "stealth" polymeric gene vector

We report on the synthesis of a novel gene carrier that has low interaction with serum components, as well as low cytotoxicity. Cationic copolymers composing branched poly(ethylenimine) (PEI) grafted with hydrophilic poly(ethylene glycol) (PEG) and poly(l-lactic acid) (PLLA) or small-molecule oleoyl were synthesized and evaluated as novel gene carriers in this study. The copolymers were complexed with plasmid DNA and the resulting polyplexes were approximately 140 nm in diameter and had a positive surface potential (ζ = +13.8 mV) at the N/P ratio of 10/1. The experiments showed that copolymers with the oleoyl moiety were superior to the other two copolymers (with PLLA), in terms of in vitro gene transfection efficiency. Safety studies using MTT assay indicated much lower cytotoxicity of the oleoyl polyplexes than the pDNA/PEI complexes. The intracellular behavior of the polyplexes was monitored by confocal laser scanning microscopy, and it was found that the polyplexes were internalized into HeLa cells very effectively. At the same time, the plasmid DNA carried by the oleoyl-containing copolymers was found to localize in the nucleus of the recipient cells. One experiment comparing serum-free and serum-containing media indicated that the oleoyl polyplexes may be able to evade the reticulo-endothelial system (RES) better than the PEI–pDNA complex.     

顺铂长循环纳米脂质体的抗肿瘤作用

目的研究顺铂长循环纳米脂质体(LDDP)的体外及体内抗肿瘤作用。方法采用逆相蒸发法制备LDDP,用四甲基偶氮唑蓝(MTT)法测定脂质原料、普通顺铂(CDDP)和LDDP对肺癌A549细胞株的毒性。以近交系C57BL/6N小鼠为受试动物,接种Lewis肺癌细胞株2 wk后,尾静脉分别注射CDDP和LDDP,剂量均为6 mg·kg~(-1);每周3次测量肿瘤体积,直到小鼠死亡或者满60 d,观察肿瘤生长为治疗前体积5倍的时间(t_(5v))和肿瘤生长延迟(TGD)时间以及生存时间。结果脂质原料体外无细胞毒性;LDDP对A549细胞株毒性大于CDDP(P<0.01),其IC_(50)为1.72 mg·L~(-1),约为CDDP(3.25 mg·L~(-1))的1/2;LDDP能显著抑制Lewis肺癌荷瘤小鼠的肿瘤生长,其TGD时间明显长于CDDP组[(12.79±3.8)d vs (3.84±1.97)d,P<0.01];同时,LDDP组的中位生存时间为41.5 d,显著长于CDDP组(25 d),P<0.01。结论本研究所采用的脂质无细胞毒性,用其制备的LDDP对肿瘤细胞的毒性高于CDDP,并可延缓Lewis肺癌荷瘤鼠的肿瘤生长,延长小鼠生存时间。     

干扰素α脂质体凝胶剂的透皮吸收作用研究

目的探讨基因重组人干扰素α-2b脂质体凝胶剂经家兔皮肤给药后的吸收作用。方法给家兔皮肤分别涂抹干扰素α-2b脂质体凝胶（试验组）和干扰素α-2b凝胶（对照组），用双抗体夹心酶联免疫吸附法（ELISA法）检测干扰素含量，测定给药后不同时间内血浆中干扰素含量及24h后皮肤层中的干扰素含量。结果与对照组比较，试验组干扰素在家兔皮肤层中有较多的滞留量（P〈0．01）；两组家兔不同时间血浆中干扰素的含量均极微少（P〉0．05）。结论脂质体作为干扰素皮肤局部给药的载体，能够提高干扰素在皮肤中的含量，但并不增加进入血液循环的干扰素量。     

紫杉醇脂质体周疗联合调强放疗在老年晚期宫颈癌患者中的应用

目的分析老年中晚期宫颈癌患者采用紫杉醇脂质体周疗联合调强放疗的临床治疗效果。方法选取2012年6月至2016年6月在本院收治的80例老年中晚期宫颈癌患者,按照随机数字表法分为观察组和对照组,各40例,观察组采用紫杉醇脂质体周疗联合调强放疗,对照组采用顺铂周疗联合调强放疗,对比观察两组患者的临床疗效、2年内生存率、总不良反应情况。结果两组患者的治疗总有效率、2年内生存率差异无统计学意义(P0.05)。观察组化疗引起的总不良反应明显低于对照组,差异有统计学意义(P0.05)。结论对老年中晚期宫颈癌患者采用紫杉醇脂质体周疗联合调强放疗的疗效安全可靠,不良反应少,提高了患者的生存质量及耐受性,具有较高的临床应用价值。     

地塞米松磷酸钠脂质体壳聚糖胶囊的结肠定位释药与吸收研究

 目的 利用壳聚糖作为载体将地塞米松磷酸钠(DSP)脂质体冻干粉剂导向结肠并探索载药脂质体经结肠黏膜吸收分布的规律性。方法 用二次乳化法,经正交试验来筛选DSP脂质体的配方。测定脂质体的包裹率和载药量,观察脂质体的形态和粒径大小分布。建立HPLC测定DSP浓度的方法。制备DSP脂质体冻干剂,将其装入壳聚糖胶囊中,再以HPMCP包裹胶囊。分别给大鼠口服各种DSP制剂,测定经时血药浓度和结肠组织中分布量,计算药物的相对靶向释药指数(DDI)。结果 用二次乳化法制备DSP脂质体时,平均包裹率为5482%,载药量为867%,粒径分布在120～265nm之间,平均粒径为178nm;口服给药时,和DSP粉剂壳聚糖胶囊或DSP溶液剂比较,DSP脂质体冻干剂壳聚糖胶囊被吸收入血的程度最低,而经时在结肠局部的分布程度最高。DSP壳聚糖胶囊结肠DDI分别是DSP溶液的2918和DSP壳聚糖胶囊的228。结论 DSP脂质体冻干剂壳聚糖胶囊较DSP粉剂壳聚糖胶囊对结肠局部组织具有更好的定位释药作用和局部治疗效果,值得进一步开发研究。     

新型载体经皮凝胶剂的研究进展

目的:对几种新型载体在经皮凝胶剂中的研究与应用进行文献整理和归纳。方法:通过查阅近20年经皮凝胶剂的相关文献,阐述几种新型载体的含义、特点及其凝胶剂经皮给药的实验性研究,比较它们与其他剂型经皮吸收的效果,归纳总结了几种新型载体凝胶经皮给药的研究近况,并提出了其在中药复方凝胶剂中的应用思路。结果:新型载体凝胶剂相对于普通凝胶剂及其他经皮给药剂型,有更强的渗透皮肤能力,能提高药物的稳定性,具有缓释性和靶向性。结论:目前,新型药物载体在经皮凝胶剂中的运用主要集中在几种常用载体和治疗皮肤疾病的药物上,随着研究的深入,必将拓宽到更多的新型药物载体和治疗非皮肤疾病的药物。新型载体凝胶剂给改善中药复方外用制剂带来启发和思考并有望在中药复方新剂型中得到应用。     

Arginine homeostasis in allergic asthma

Allergic asthma is a chronic disease characterized by early and late asthmatic reactions, airway hyperresponsiveness, airway inflammation and airway remodelling. Changes in l-arginine homeostasis may contribute to all these features of asthma by decreased nitric oxide (NO) production and increased formation of peroxynitrite, polyamines and l-proline. Intracellular l-arginine levels are regulated by at least three distinct mechanisms: (i) cellular uptake by cationic amino acid (CAT) transporters, (ii) metabolism by NO-synthase (NOS) and arginase, and (iii) recycling from l-citrulline. Ex vivo studies using animal models of allergic asthma have indicated that attenuated l-arginine bioavailability to NOS causes deficiency of bronchodilating NO and increased production of procontractile peroxynitrite, which importantly contribute to allergen-induced airway hyperresponsiveness after the early and late asthmatic reaction, respectively. Decreased cellular uptake of l-arginine, due to (eosinophil-derived) polycations inhibiting CATs, as well as increased consumption by increased arginase activity are major causes of substrate limitation to NOS. Increasing substrate availability to NOS by administration of l-arginine, l-citrulline, the polycation scavenger heparin, or an arginase inhibitor alleviates allergen-induced airway hyperresponsiveness by restoring the production of bronchodilating NO. In addition, reduced l-arginine levels may contribute to the airway inflammation associated with the development of airway hyperresponsiveness, which similarly may involve decreased NO synthesis and increased peroxynitrite formation. Increased arginase activity could also contribute to airway remodelling and persistent airway hyperresponsiveness in chronic asthma via increased synthesis of l-ornithine, the precursor of polyamines and l-proline. Drugs that increase the bioavailability of l-arginine in the airways – particularly arginase inhibitors – may have therapeutic potential in allergic asthma.     

Non-viral dried powders for respiratory gene delivery prepared by cationic and chitosan loaded liposomes

The aim of this work was to investigate lipid-based dried powders as transfection competent carriers capable of promoting the expression of therapeutic genes. The lipid-based vectors were prepared by combining different cationic lipids 1,2-dioleoyl-3-trimethylammoniumpropane chloride (DOTAP), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 3beta(N(N',N-dimethylaminoethane) carbamoyl) cholesterol hydrochloride (DC-Chol) or by mixing of anionic lipids (1,2-dimyristoyl-sn-glycero-3-phospocholine (DMPC), 1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol sodium salt (DMPG) and chitosan salts. Spray drying of the formulations was performed using carbohydrates as thermoprotectant excipients and some amino acids as aerosolisation enhancers. Both the lipidic vectors and the dried powders were characterized for morphology, size, zeta potential (Z-potential) and a yield of the process. Agarose gel electrophoresis was used to examine the structural integrity of dehydrated plasmid DNA (pDNA). The biological functionality of the powders was quantified using the in vitro cell transfection. Among the several lipids and lipid-polymer mixtures tested, the best-selected formulations had spherical shape, narrow size distribution (mean diameter<220 nm, P.I.<0.250), a positive zeta-potential (>25 mV) with a good yield of the process (>65%). The set-up spray drying parameters allowed to obtain good yield of the process (>50%) and spherically shaped particles with the volume-weighted mean diameter (d[4,3])<6 microm in the respirable range. The set-up conditions for the preparation of the lipid dried powders did not adversely affect the structural integrity of the encapsulated pDNA. The powders kept a good transfection efficiency as compared to the fresh colloidal formulations. Lipid-based spray dried powders allowed the development of stable and viable formulations for respiratory gene delivery. In vitro dispersibility and deposition studies are in progress to determine the aerosolisation properties of the powders.     

以叶酸受体为靶向的阳离子脂质体的制备与性质考察

为了研制一种能通过叶酸受体途径靶向肿瘤细胞的叶酸受体靶向脂质体，将叶酸(folate，folic acid，F)、 聚乙二醇二胺(polyoxyethylene-bis-amine，NH₂-PEG-NH₂)、 琥珀酸酐(succinic anhydride，SUC)和二硬脂酰磷脂酰乙醇胺(distearoylphosphatidylethanolamine，DSPE)按序共价连接， 并使用薄层色谱和飞行时间质谱确证合成产物为叶酸-聚乙二醇-二硬脂酰磷脂酰乙醇胺(folate-polyethyleneglycol-distearoylphosphatidylethanolamine，F-PEG-DSPE)。膜材选用二棕榈酰磷脂酰胆碱(dipalmitoylphosphatidylcholine，DPPC)， 3β-［N-(N′,N′-二甲基胺乙基)胺基甲酰基］胆固醇(3β-［N(N′,N′-dimethylaminoethane) carbamoyl］ cholesterol，DC-Chol)和F-PEG-DSPE，以10∶10∶0.75(摩尔比)的配比，以荧光素标记的阴离子葡聚糖(dextran fluorescein anionic，DFA)为模型，用薄膜分散法制备含DFA的叶酸受体靶向脂质体，其包封率较高(>55%)、稳定性好，平均粒径为144 nm，体外释放慢。MTT法考察其对细胞的毒性结果表明该阳离子脂质体具有一定的细胞毒性，在低浓度时(0.012 5～0.1 μmol·L^{-1)脂质体的细胞毒性与DC-chol浓度成正比。流式细胞技术检测KB细胞和HepG2细胞对DFA脂质体的摄取，结果表明叶酸受体靶向的长循环阳离子脂质体能提高细胞对脂质体的摄取。该研究为进一步研究叶酸受体靶向阳离子脂质体在肿瘤基因治疗中的应用提供了理论基础。}     

神经生长因子脂质体大鼠鼻腔给药的药效学研究

 目的对神经生长因子(nerve growth factor,NGF)和NGF脂质体(NGF-SSL)鼻腔给药的药效学进行研究,并与NGF静脉给药相比较。方法鹅膏蕈氨酸(ibotenicacid,IBO)大鼠Meynert核注射制造阿尔茨海默氏病(alzheimer'sdisease,AD)模型,以生理盐水Meynert核注射作为假手术对照组,通过水迷宫试验,跳台实验和乙酰胆碱酯酶(AchE)组织化学染色来评价AD模型。并应用此模型采用同样方法研究NGF静脉给药,NGF和NGF-SSL鼻腔给药后的药效。结果AD模型经鉴定能够应用于药效研究。NGF鼻腔给药药效优于NGF静脉注射,NGF经脂质体包载后药效进一步提高。NGF-SSL鼻腔给药后能明显保护胆碱能神经元免受损伤,动物游泳时间缩短,跳台潜伏期延长,AchE染色积分光密度接近正常大鼠。结论鼻腔给药能够实现药物给药途径上的脑靶向,药物经脂质体包载后能明显增加其脑摄入,提高药效。