Poly(ethylene glycol)-block-cationic polylactide nanocomplexes of differing charge density for gene delivery

Representing a new type of biodegradable cationic block copolymer, well-defined poly(ethylene glycol)-block-cationic polylactides (PEG-b-CPLAs) with tertiary amine-based cationic groups were synthesized by thiol-ene functionalization of an allyl-functionalized diblock precursor. Subsequently the application of PEG-b-CPLAs as biodegradable vectors for the delivery of plasmid DNAs (pDNAs) was investigated. Via the formation of PEG-b-CPLA:pDNA nanocomplexes by spontaneous electrostatic interaction, pDNAs encoding luciferase or enhanced green fluorescent protein were successfully delivered to four physiologically distinct cell lines (including macrophage, fibroblast, epithelial, and stem cell). Formulated nanocomplexes demonstrated high levels of transfection with low levels of cytotoxicity and hemolysis when compared to a positive control. Biophysical characterization of charge densities of nanocomplexes at various polymer:pDNA weight ratios revealed a positive correlation between surface charge and gene delivery. Nanocomplexes with high surface charge densities were utilized in an in vitro serum gene delivery inhibition assay, and effective gene delivery was observed despite high levels of serum. Overall, these results help to elucidate the influence of charge, size, and PEGylation of nanocomplexes upon the delivery of nucleic acids in physiologically relevant conditions.     

Crucial role of marginal zone macrophages and marginal zone metallophils in the clearance of lymphocytic choriomeningitis virus infection

Macrophages play a key role in the immune defense against pathogens. They control early invasion by antigen-unspecific phagocytosis of pathogens and act as professional antigen-presenting cells to induce antigen-specific T cell responses. To investigate the involvement of particular subsets of the splenic macrophages in an antiviral immune response, we selectively depleted mice of splenic marginal zone macrophages (MZM) and marginal zone metallophils (MM) using the clodronate liposome depletion technique. MZM- and MM-depleted mice were not able to control an infection with lymphocytic choriomeningitis virus (LCMV). In these mice, LCMV spread from the spleen to peripheral organs at an early phase of infection. The virus-specific cytotoxic T lymphocyte (CTL) response was induced initially, yet was exhausted in parallel with the overwhelming virus replication. These findings suggest that MZM and MM play a crucial role in the early control of a LCMV infection by preventing immediate virus spread to peripheral organs, but are not essential for the induction of the LCMV-specific CTL response.     

长循环脂质体的研究进展及其在核医学中的应用

脂质体作为药物载体具有很多优点,但是其主动靶向性和稳定性较差,聚乙二醇或与配体连接的聚乙二醇修饰的脂质体,即长循环脂质体,具有延长脂质体在血液循环中的半衰期、提高其稳定性、改变脂质体在体内的生物学分布,赋予脂质体靶向性的优点。本文主要综述了长循环脂质体的研究进展及其在核医学中的应用。     

叶酸偶联纳米紫杉醇脂质体在大鼠体内的药物代谢动力学研究

目的探讨叶酸偶联纳米紫杉醇脂质体在大鼠体内的药物代谢动力学。方法将SD大鼠尾静脉注射叶酸偶联纳米紫杉醇脂质体（实验组）及普通紫杉醇脂质体（对照组）,采用高效液相色谱分析紫外（HPLC—UV）法检测两组大鼠体内血药浓度经时变化,Excel绘制药物经时曲线。药物代谢统计分析软件（DAS）模拟房室模型并计算药代动力学参数。结果①紫杉醇标准品血样在0．07-30μg／ml浓度时呈良好的线性关系,浓度测定的日内、日间精密度的相对标准偏差（RSD）值〈6％,高（10．0μg／ml）、中（2．0μg／ml）、低（0．2μg／ml）浓度下的紫杉醇标准品血样的提取回收率均〉90％;②实验组血药浓度经时曲线符合1／C权重的三室模型,对照组符合1／C2权重的二室模型;③实验组药物快、慢分布相半衰期分别是（0．12±0．10）h和（0．40±0．08）h,消除半衰期是（3．29±1．02）h,血浆清除率（CL）是（1．37±0．04）L／（kg·h）,0～t时血药浓度一时间曲线下面积（AUC）及AUC（0～∞）分别是（12．19±0．40）mg／（L·h）和（14．61±0．40）mg／（L·h）;对照组药物分布相半衰期是（0．09±0．08）h,消除半衰期是（2．57±0．51）h,CL是（1．50±0．10）L／（kg·h）,AUC（0～t）及AUC（0～∞）分别是（9．30±0．48）mg／（L·h）和（13．39±0．92）mg／（L·h）;两组消除半衰期、CL、AUC（0-t）和AUC（0～∞）比较,差异均有统计学意义（P〈0．05）。结论叶酸偶联纳米紫杉醇脂质体与普通紫杉醇脂质体均能较快地分布于体内并达到平衡,但是前者半衰期较长,清除速度略快,生物利用度高。     

曲妥珠单抗联合阿霉素脂质体治疗HER-2过度表达乳腺癌的临床疗效分析

目的:总结曲妥珠单抗联合阿霉素与曲妥珠单抗联合阿霉素脂质体治疗人表皮生长因子-2(HER-2)过度表达的乳腺癌的疗效和安全性。方法:经细胞学证实的HER-2过度表达的60例乳腺癌患者,25例接受曲妥珠单抗联合阿霉素化疗方案(A组),35例接受曲妥珠单抗联合阿霉素脂质体(B组)方案化疗。参照实体瘤疗效评价标准进行疗效判定,按照美国国立研究院通用毒性标准评价不良反应。结果:58例患者可评价疗效,A组完全缓解率为16.0%,部分缓解率为20.0%,总有效率为36.0%;B组完全缓解率为18.2%,部分缓解率为30.3%,总有效率为48.5%;B组患者的生存时间比A组患者的生存时间长;A组和B组的主要不良反应为粒细胞减少、心脏毒性、恶心呕吐等。结论:曲妥珠单抗联合阿霉素脂质体可以提高治疗HER-2阳性表达的乳腺癌患者的有效率,并且延长患者的生存时间。     

总姜黄素脂质体的包封率和体外释药测定

目的:研究总姜黄素脂质体的包封率测定方法,初步考察其体外释放规律。方法:用乙醇注入法制备了总姜黄素脂质体,葡聚糖凝胶 G-50柱分离方法测定脂质体的包封率,并用溶出度第三法考察脂质体的体外释放过程。分析柱为岛津 C_(18)色谱柱(150 mm×4.6 mm,5μm),乙腈-水-冰醋酸(45:55:2)为流动相,流速1mL·min~(-1),检测波长430nm。结果:总姜黄素脂质体的平均包封率为64.4%,体外释放符合一室模型。结论:该方法简便、易操作,可作为总姜黄素脂质体包封率和体外释药的研究。     

Phase II trial of pegylated-liposomal doxorubicin (Doxil) in renal cell cancer

Twelve patients with refractory renal cell cancer weretreated on a phase II study of pegylated-liposomaldoxorubicin (Doxil). The initial dose per course was55 mg/m² every four weeks with dose modification based onmucositis and hand-foot syndrome (the main limitingtoxicities). Toxicities were mild and similar to previousreports but dose reduction per the study protocol, which wasdesigned to control the skin and mucosal toxicities, wascommon. No definite cardiac toxicity was observed. Noobjective responses were observed in 11 evaluable patients. This study did not demonstrate activity ofpegylated-liposomal doxorubicin in renal cell cancer,although it can be given with mild toxicity.     

Targeting Efficiency of Galactosylated Liposomes to Hepatocytes in Vivo: Effect of Lipid Composition

Purpose. To investigate the effects of the lipid composition of galactosylated liposomes on their targeted delivery to hepatocytes. Methods. Several types of liposomes with a particle size of about 90 nm were prepared using distearoyl-L-phosphatidylcholine (DSPC), cholesterol (Chol) and cholesten-5-yloxy-N-(4-((1-imino-2-D-thiogalactosylethyl)amino)butyl)formamide (Gal-C4-Chol), and labeled with [³H]cholesterol hexadecyl ether. Their tissue disposition was investigated in mice following intravenous injection. The binding and internalization characteristics were also studied in HepG2 cells. Results. Compared with [³H]DSPC/Chol (60:40) liposomes, [³H]D-SPC/Chol/Gal-C4-Chol (60:35:5) liposomes exhibit extensive hepatic uptake. Separation of the liver cells showed that galactosylated liposomes are preferentially taken up by hepatocytes, whereas those lacking Gal-C4-Chol distribute equally to hepatocytes and nonparenchymal cells (NPC). Increasing the molar ratio of DSPC to 90% resulted in enhanced NPC uptake of both liposomes, suggesting their uptake via a mechanism other than asialoglycoprotein receptors. DSPC/Chol/Gal-C4-Chol (60:35:5) and DSPC/Chol/Gal-C4-Chol (90:5:5) liposomes exhibited similar binding to the surface of HepG2 cells, but the former were taken up faster by the cells. Conclusions. The recognition of galactosylated liposomes by the asialoglycoprotein receptors is dependent on the lipid composition. Cholesterol-rich galactosylated liposomes, exhibiting less non-specific interaction and greater receptor-mediated uptake, are better for targeting drugs to hepatocytes in vivo.