Size and surface charge effect of 5-aminolevulinic acid-containing liposomes on photodynamic therapy for cultivated cancer cells

5-Aminolevulinic acid (ALA)-containing liposomes having various average diameters and/or positive surface charges were prepared, and their photodynamic therapy (PDT) efficacy for murine thymic lymphoma cells, EL-4 cells, cultivated in vitro was investigated. The PDT efficacy for EL-4 cells and the accumulation of ALA-induced protoporphyrin IX (PpIX) in the cells increased with a decrease in the average diameter of liposomes. In particular, the ALA-containing liposomes smaller than 63.5 nm in diameter promoted the PDT efficacy in comparison with that of ALA alone. We also found no significant changes in PDT efficacy and PpIX accumulation with increasing positive surface charges of liposomes.     

人用狂犬病毒脂质体疫苗的制备及性质

目的制备人用狂犬病毒脂质体疫苗,并考察其制剂学及毒理学性质。方法以氢化大豆磷脂、胆固醇、十八胺为原料,采用反相蒸发法(REV)制备脂质体,加入纯化狂犬病毒抗原,以冻干重建法(DRV)制备狂犬病毒脂质体疫苗。在电镜下观察其形态,测定其包封率和体外释放率,用激光衍射粒度分析仪测定其粒径分布及平均粒径,并进行局部刺激性、过敏反应及异常毒性试验。结果所制备的狂犬病毒脂质体疫苗形态呈圆形或椭圆形,粒径分布均匀,平均粒径为12.25μm左右,包封率在60%以上。无刺激性,无异常毒性,过敏反应检测合格。结论所制备的狂犬病毒脂质体疫苗性质稳定,可作进一步研究。     

维生素C脂质体的制备与研究

采用改进薄膜法制备维生素C脂质体,以卵磷脂:胆固醇=6:1制成空白脂质体,以空白脂质体:维生素C=9:2,超声处理3min,并经稳定化处理后得到维生素C脂质体,包封率最高可达18.09%;电子显微镜下观察结果显示产品为单室脂质体,粒径集中在20～50nm之间;低温贮存环境有利于脂质体的稳定.     

脂质体流感疫苗的制备及免疫效果

目的制备脂质体流感疫苗,并对其细胞免疫效果和小鼠保护效力进行检测。方法采用薄膜蒸发与冷冻干燥相结合的方法制得多层脂质体,与流感裂解疫苗按比例混合,制备脂质体流感疫苗。用该疫苗免疫BALB/c小鼠,MTT法检测小鼠淋巴细胞增殖情况;流式细胞仪检测小鼠T淋巴细胞表面标记;ELISA法检测小鼠肺内容物中细胞因子含量;并检测小鼠的保护效力。结果在脾细胞增殖效率、CD4+水平、CD4+/CD8+比例以及细胞因子(IL-4、IFN-γ)水平上,实验组均有显著的增强作用,保护效力为4/6。结论脂质体流感疫苗能够刺激机体产生更强的细胞免疫应答和更高的保护效力。     

Inhibiting the vascular smooth muscle cells proliferation by EPC and DPPC liposomes encapsulated magnolol

Percutaneous transluminal coronary angioplasty (PTCA) is a non-surgical modality for treating stennosis. However, the recurrence of restenosis in 30-50% patients within 6 months is the major drawback of PTCA. The major reason of restenosis is the proliferation of the vascular smooth muscle cells (VSMCs). Magnolol, a pure compound extracted from Magnolia officinalis, encapsulated by liposome was investigated for inhibiting the VSMCs proliferation leading to restenosis by PTCA. 1,2-Diacyl-Sn-glycero-3-phosphocholine (EPC) and 1,2-dipalmitoyl-Sn-glycero-3-phosphocholine (DPPC) liposomes were utilized to encapsulate the magnolol. EPC liposome obtained the higher encapsulation efficiency than DPPC lipsomes from UV-vis spectroscopy study. The inhibiting efficiency of EPC and DPPC liposomes encapsulated magnolol was higher than pure magnonol. Magnolol encapsulated by EPC liposomes had better efficiency on inhibiting VSMCs than DPPC liposome. Addition of cholesterol in liposomes could slightly enhance the encapsulation efficiency. The particles sizer analysis revealed the average particles size of EPC and DPPC liposomes encapsulated magnolol became larger than pure EPC or DPPC liposomes. From the transmission electron microscopy (TEM) analysis, the magnolol seems to interfere with EPC and DPPC liposomes to form a homogeneous lipid bilayer.     

精子干细胞转染法制备转基因兔的研究

采用直接注射的方法 ,将脂质体包裹的含人乳铁蛋白基因重组质粒 pLNCXHLF注入兔睾丸组织中 ,一个月后与正常雌兔交配。所产仔兔经PCR、Southern检测证明获得了转基因兔 ,转基因阳性率平均为 35 %。实验结果表明 ,通过注射可将外源基因导入到曲细精管中 ,进而完成对精子干细胞的转染 ,获得携带外源基因的成熟精子 ,受精后可得到转基因动物。该方法是一种简捷、有效的新途径 ,既节省时间又降低了成本 ,为利用精子载体制备转基因动物的研究提供了很有价值的参考。     

Enhanced localization of anticancer drug in tumor tissue using polyethylenimine-conjugated cationic liposomes

Liposome-based drug delivery systems hold great potential for cancer therapy. However, to enhance the localization of payloads, an efficient method of systemic delivery of liposomes to tumor tissues is required. In this study, we developed cationic liposomes composed of polyethylenimine (PEI)-conjugated distearoylglycerophosphoethanolamine (DSPE) as an enhanced local drug delivery system. The particle size of DSPE-PEI liposomes was 130 ± 10 nm and the zeta potential of liposomes was increased from -25 to 30 mV by the incorporation of cationic PEI onto the liposomal membrane. Intracellular uptake of DSPE-PEI liposomes by tumor cells was 14-fold higher than that of DSPE liposomes. After intratumoral injection of liposomes into tumor-bearing mice, DSPE-PEI liposomes showed higher and sustained localization in tumor tissue compared to DSPE liposomes. Taken together, our findings suggest that DSPE-PEI liposomes have the potential to be used as effective drug carriers for enhanced intracellular uptake and localization of anticancer drugs in tumor tissue through intratumoral injection.     

Aβ/Cu-catalyzed oxidation of cholesterol in 1,2-dipalmitoyl phosphatidylcholine liposome membrane

The amyloid β protein with 42 amino acid residues (Aβ), which is a causative protein of Alzheimer's disease (AD), forms the complex with copper (II) to induce the cholesterol oxidase-like activity by the proton transfer from the cholesterol. In this study, the oxidation of cholesterol by Aβ/Cu complex was investigated on the surface of the zwitterionic phospholipid liposome including the bound water advantageous for the enhancement of the proton transfer. The bound water was pooled by the formation of cholesterol-rich domain within liposomes. The resulting reactivity was enhanced by the proton transfer mediated by the bound water.     

Antioxidant properties of anthocyanidins,anthocyanidin-3-glucosides and respective portisins

The study of the antioxidants properties of three classes of pigments, namely anthocyanidins (cyanidin-Cy, delphinidin-Dp and malvidin-Mv), anthocyanidin-3-glucosides (Cy-3-gluc, Dp-3-gluc and Mv-3-gluc), and portisins (Cy-pt, Dp-pt and Mv-pt) was carried out. The aim was to evaluate the relationship between the structure antioxidant properties of individual anthocyanins and respective derivative pigments. The ability of these compounds to inhibit lipid peroxidation in a liposome membrane system was examined by monitoring oxygen consumption and the antiradical and reducing capacities were determined using the DPPH and FRAP assay, respectively. All compounds tested showed antiradical and reducing properties. These features seemed to increase with the presence of catechol and pyrogallol groups in ring B of anthocyanidin-3-glucosides and respective aglycones. The results obtained for portisins are very likely to be related with their unique structural features. The flavanol moiety of the compounds structure seems to be crucial for the antiradical properties, whilst their reducing ability was only evident for the portisin derived from malvidin. This outcome could be due to some of the structural features of these pigments as they are complex structures and may have several different conformations in solution. The antioxidant protection towards lipid peroxidation increased with the overall hydrophobicity of the compounds. This feature is related to the location of the antioxidant on the liposome surface vs. water phase. Among the pigments tested, portisins showed the higher effect in preventing lipid peroxidation of soybean phosphatidylcholine liposomes, especially the portisin derived from Cy. This outcome could be due to the presence of two o-catechol groups in the structure of this compound.