热敏靶向脂质体在肿瘤治疗中的研究进展

介绍热敏靶向脂质体在肿瘤热疗中的应用以及国内外研究的现状，并介绍热敏长循环脂质、磁性热敏脂质体、免疫热敏脂质体和多聚物热敏脂质体等新型热敏靶向脂质体的特点和应用。     

磁性热敏脂质体的研究进展

磁性热敏脂质体是近年来兴起的一种新型靶向药物载体,它可以在外加磁场的作用下随血液循环聚集到靶器官,在不加磁场或正常体温条件下应使包裹在脂质体中的药物缓慢、平稳释放并起到药品储库作用;而在体外交变磁场作用下产热达到热敏脂质体相变温度而控制包裹在脂质体中的药物迅速释放,以达到在肿瘤组织靶向、多次和脉冲式给药的效果。与普通脂质体相比,磁性热敏脂质体具有更强的组织靶向性和控释特性。本文综述了磁性热敏脂质体的制备、磁定位靶向性和热敏释药性。     

热敏脂质体

目的:综述热敏脂质体的原理和它作为靶向药物载体的应用。方法:论述了脂质体相变的原理和热敏脂质体的研究概况,以及携带化疗药物的热敏脂质体和肿瘤热疗结合后治疗效果的增强作用,指出了热敏脂质体的发展前景。结果:热敏脂质体有良好的热靶向性,在肿瘤治疗方面效果明显。结论:热敏脂质体是新一代热靶向药物载体,有重要的开发价值。     

热敏脂质体

目的:综述热敏脂质体的原理和它作为靶向药物载体的应用。方法:论述了脂质体相变的原理和热敏脂质体的研究概况,以及携带化疗药物的热敏脂质体和肿瘤热疗结合后治疗效果的增强作用,指出了热敏脂质体的发展前景。结果:热敏脂质体有良好的热靶向性,在肿瘤治疗方面效果明显。结论:热敏脂质体是新一代热靶向药物载体,有重要的开发价值。     

电磁波控制热敏磁性脂质体靶向给药

本文从新型靶向给药系统-热敏磁性脂质体靶向给药的几个关键之处出发，介绍了目前热敏磁性脂质体的脂质材料、磁性材料、磁定位和电磁波控释研究状况，分析讨论了电磁波在热敏磁性脂质体的磁靶向和药物控释方面的作用,并提出了测量热敏磁性脂质体的电磁参数和选择合适的电磁波频段用于药物控释的必要性。     

主动靶向热敏脂质体在肿瘤光热治疗中的应用研究

靶向热敏脂质体是近年来新兴起的一种新型药物载体,其以低毒、靶向、高效等优点受到相关研究者们越来越多的关注。为了进一步提高抗肿瘤药物的靶向性、治疗效果和生物利用度,更多功能更多新靶点的热敏脂质体出现,且在肿瘤的光热治疗中扮演着重要角色。将其与光热治疗相结合,可进一步提高肿瘤的治疗效果。经过查阅和整理近年来国内外相关文献,综述当前主动靶向热敏脂质体的研究现状并展望其在肿瘤光热治疗中的发展前景。     

甲氨蝶呤热敏磁靶向脂质体的制备和靶向性研究

采用正交设计以37℃和43℃释出的游离药物之比为评价指标优化甲氨蝶呤热敏磁靶向脂质体处方。并测定了小鼠尾静脉注射甲氨蝶呤溶液和甲氨蝶呤脂质体后,全血和肌肉中的药物浓度。结果表明,给予甲氨蝶呤脂质体后再外加磁场并置于43℃环境,脂质体靶向效率Te提高6.8倍,相对摄取量Re提高6.5倍。说明本实验制备的脂质体具有很高的靶向性。     

新型阿霉素热敏脂质体的研制

目的:探讨以二棕榈酰磷脂酰胆碱(DPPC)和单棕榈酰磷脂酰胆碱(MPPC)为原料制备的温度敏感阿霉素脂质体的制备工艺和理化性质.方法:采用膜过滤挤压法和pH梯度法制备阿霉素脂质体,以紫外分光光度法检测样本中阿霉素含量,计算阿霉素热敏脂质体在不同温度下的药物释放特性,并对其包裹率、粒径,pH值进行研究.结果:阿霉素热敏脂质体在39℃下迅速释放,前20 s内释放药物50%,42℃下药物释放达到60%以上.包封率99.5%,平均粒径90.8 nm,pH值为6.5.结论:制备的热敏感阿霉素脂质体优于常规脂质体,具有良好的温度控释特性.     

同位素标记法研究8-甲氧补骨脂素脂质体凝胶的皮肤靶向性

采用~3H同位素标记8-甲氧补骨脂素脂质体凝胶、脂质体、凝胶和酊剂,给予SD大鼠后,以液体闪烁仪测定皮肤及血液中~3H标记的8-甲氧补骨脂素含量。考察剂型、脂质组成、粒径和电荷等因素对脂质体凝胶皮肤靶向性的影响。结果显示,以二棕榈酰磷脂酰胆碱(DPPC)为膜材或加入带负电荷胆固醇硫酸酯的脂质体凝胶可增加皮肤靶向性。研究表明,脂质组成、粒径和电荷对脂质体凝胶的皮肤靶向性均有较大影响。     

主动靶向脂质体的相变温度与靶细胞摄取的相关性研究

分别采用二硬脂酰磷脂酰胆碱(DSPC)、氢化大豆磷脂(HSPC)、二棕榈酰磷脂酰胆碱(DPPC)和二肉豆蔻酰磷脂酰胆碱(DMPC)为载体,制备了NGR肽(Asn-Gly-Arg)修饰的主动靶向脂质体,并用其负载香豆素-6.结果表明,4种脂质体的粒径为120～160 nm,粒度分布均匀,ζ电位接近中性,包封率均在95％以上.差示扫描量热分析(DSC)表明,4种脂质体的相变温度(Tm)值由高至低分别为DSPC脂质体＞HSPC脂质体＞DPPC脂质体＞DMPC脂质体.以CD13高表达的HT1080细胞为模型,采用流式细胞仪、激光共聚焦显微镜观察评价脂质体的入胞效果.结果显示,脂质体的入胞效率与Tm值呈正相关.     

川芎嗪眼用脂质体温敏凝胶的制备及体内外特性评价

目的:制备川芎嗪眼用脂质体温敏凝胶,考察其体内外特性。方法:采用硫酸铵梯度法制备川芎嗪脂质体,以正交试验优化制备工艺,并以泊洛沙姆P407为凝胶基质进一步制成温敏凝胶。采用无膜溶出模型对该凝胶的溶蚀性和体外释药特性进行研究;采用改良Franz扩散池考察其角膜透过性,并进一步测定角膜水化值;采用MTT法评价该凝胶对人角膜上皮细胞HCE-T增殖的影响;采用苏木素-伊红染色法和Draize眼部刺激评分考察该凝胶对家兔角膜的刺激性,并观察其眼部组织学变化。结果:川芎嗪脂质体的最优制备工艺为药脂比1∶10(m/m)、硫酸铵溶液浓度0.2 mol/L、磷脂与胆固醇质量比4∶1、孵育温度45℃;再以23%质量分数的泊洛沙姆P407作为凝胶基质制得川芎嗪眼用脂质体温敏凝胶。该凝胶具有良好的胶凝温度;其溶蚀和体外释药均呈零级动力学特征,且体外释药主要与溶蚀相关(R2=0.9934)。该凝胶6 h内累计透过量为43.3%;角膜水化值为72.98%。低、中质量浓度(1、5 mg/L)的川芎嗪眼用脂质体温敏凝胶对HCE-T细胞无明显增殖毒性,但其在高质量浓度(10 mg/L)时显示出一定的细胞毒性。该凝胶对家兔角膜的Draize眼部刺激平均评分属于无刺激范围,且家兔角膜组织学未见异常变化。结论:所制备的川芎嗪眼用脂质体温敏凝胶具有适宜的胶凝温度,对角膜渗透性好、刺激性小。     

A new vaginal delivery system of amphotericin B: a dispersion of cationic liposomes in a thermosensitive gel

Amphotericin B (AmB) is used in the treatment of fungal infections; however, its clinical use is limited by its toxic side effects. In this study, AmB-loaded cationic liposome gels were formulated with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), and cholesterol (CH) at a molar ratio of DOPE:DOTAP:CH?=?4:5:1 in thermosensitive gel composed of poloxamer 407 (P407) and poloxamer 188 (P188). To enhance the solubility of AmB, 6 mol% of distearoyl phosphatidyl ethanolamine–polyethylene glycol was added prior to encapsulation of the drug into liposomes. Scanning electron microscopy was used to observe the AmB encapsulated cationic liposome gels. In vitro release, stability and cytotoxicity of AmB in cationic liposome gels were evaluated. The particle size and zeta potential of AmB-loaded liposomes were in the range of 400–500?nm and 40–60 mV, respectively. The thermosensitive gel at the ratio of P407:P188?=?15:15 (w/w) gelled at 37°C, approximating body temperature. Encapsulation efficiency of AmB was ～50–60%, which was influenced by the ratio of AmB to lipid. Moreover, AmB-loaded cationic liposome gels were more stable and less toxic than free AmB. From these results, cationic liposome gel formulations may be useful for vaginal delivery of AmB.     

Increased tumor cisplatin levels in heated tumors in mice after administration of thermosensitive, large unilamellar vesicles encapsulating cisplatin

Hyperthermia (HT)-dependent cisplatin (CDDP) release and tumor CDDP level increase after the administration of thermosensitive, large unilamellar vesicles (LUVs: LUV-1 and LUV-2) and a thermosensitive, small unilamellar vesicle (SUV: SUV-1) were examined in comparison with those following administration of a non-thermosensitive LUV (LUV-3) and a CDDP solution (Sol) in tumor bearing mice. The LUV-1 and LUV-2 released CDDP at a faster rate than SUV-1 when incubated in saline at temperatures between 41 and 44 degrees C. The blood CDDP levels after liposome administration were higher than those after Sol administration. The systemic clearance of LUV-2 was slightly larger than those of the other liposomes. The tumor CDDP levels after thermosensitive liposome administration were increased in response to HT in comparison to LUV-3 or Sol. The increased ratio for LUV-1 was the largest. The ratio of the area under the tumor CDDP level versus time curve (AUC) for LUV-1 + HT to the AUC for Sol + HT was approximately 5. The results indicate that (1) the tumor-CDDP level increase after thermosensitive liposome administration is due to CDDP release from the liposome in the blood at or adjacent to the heated tumor, (2) the increase is highly dependent on the heat sensitivity and systemic stability of the liposome, and (3) LUV, such as LUV-1, exhibit higher heat sensitivity and larger, targeted drug delivery efficiency than SUV.     

奥沙利铂长循环热敏脂质体及其药效学研究

目的制备奥沙利铂长循环热敏脂质体(oxaliplatinlong-circulating-thermosensitive liposomes,OLTL),并考察其性质及抑瘤作用。方法采用薄膜分散法制备OLTL;透析法考察OLTL在37℃和42℃下的体外释药;免疫抑制法建立荷Lewis肺癌小鼠模型,以瘤重为指标考察OLTL的抑瘤作用。结果带有蓝色乳光的OLTL粒径在100～130 nm之间,包封率大于90%;42℃条件下,OLTL释药率达90%以上;OLTL组抑瘤率为70.79%。结论 OLTL具有良好的热敏释药特性,可明显提高奥沙利铂(oxaliplatin)的抑瘤作用。     

Hydroxycamptothecin liposomes based on thermal and magnetic dual-responsive system: preparation,in vitro and in vivo antitumor activity,microdialysis-based tumor pharmacokinetics

Due to the absence of lactone form of hydroxycamptothecin, the commercially available hydroxycamptothecin injection exhibits inefficient therapeutic effects. In this study, we constructed a novel delivery system (thermosensitive magnetic liposomes) that protects lactone form of hydroxycamptothecin from blood or water. After hydroxycamptothecin was loaded into the thermosensitive magnetic liposome (HCPT/TML), its in vitro and in vivo antitumor activity and microdialysis-based tumour pharmacokinetics were determined. The results demonstrated that HCPT/TMLs possessed favourable physicochemical features and significant cytotoxicity against the Huh-7 cells in vitro. In the in vivo antitumor study and tumour pharmacokinetics, HCPT/TMLs displayed effective targeting delivery and antitumor effects, which corresponded to the determined hydroxycamptothecin concentration in tumour tissue. In conclusion, this thermal and magnetic dual-responsive system can efficiently deliver hydroxycamptothecin to tumour tissue and has great potential application in cancer treatment.     

Near-Infrared Image-Guided Delivery and Controlled Release Using Optimized Thermosensitive Liposomes

Purpose

To engineer optimized near-infrared (NIR) active thermosensitive liposomes to potentially achieve image-guided delivery of chemotherapeutic agents.

Methods

Thermosensitive liposomes were surface-coated with either polyethylene glycol or dextran. Differential scanning calorimetry and calcein release studies were conducted to optimize liposomal release, and flow cytometry was employed to determine the in vitro macrophage uptake of liposomes. Indocyanine green (ICG) was encapsulated as the NIR dye to evaluate the in vivo biodistribution in tumor-bearing mice.

Results

The optimized thermosensitive liposome formulation consists of DPPC, SoyPC, and cholesterol in the 100:50:30 molar ratio. Liposomes with dextran and polyethylene glycol demonstrated similar thermal release properties; however in vitro macrophage uptake was greater with dextran. Non-invasive in vivo NIR imaging showed tumor accumulation of liposomes with both coatings, and ex vivo NIR imaging correlated well with actual ICG concentrations in various organs of healthy mice.

Conclusions

The optimized thermosensitive liposome formulation demonstrated stability at 37?°C and efficient burst release at 40 and 42?°C. Dextran exhibited potential for application as a surface coating in thermosensitive liposome formulations. In vivo studies suggest that liposomal encapsulation of ICG permits reliable, real-time monitoring of liposome biodistribution through non-invasive NIR imaging.     

Heat-Induced Drug Release Rate and Maximal Targeting Index of Thermosensitive Liposome in Tumor-Bearing Mice

To evaluate the rate of drug release at the tumor and maximal drug targeting after administration of thermosensitive liposomes with hy-perthermia, a theoretical and experimental method was derived assessing the fraction of drug released from liposomes in a single pass through the heated tumor, F, and the drug targeting index when drug release occurs completely in response to heat (F = 1), DTI_max. The F and DTImax were evaluated for four types of liposomes (LUV-1 and LUV-2, thermosensitive large unilamellar liposomes; LUV-3, a nonthermosensitive large unilamellar liposome; and SUV-1, a thermosensitive small unilamellar liposome) using reported data on blood liposome levels and tumor drug levels after the liposomes were administered to tumor bearing mice. DTI_max values for LUV-1 and SUV-1 were approximately 6, while the value for LUV-2 with a relatively large systemic clearance was only 2.3. The F values for LUV-1, LUV-2, and SUV-1 with hyperthermia were 0.71, 1.17, and 0.34, respectively, whereas the values for these liposomes without hyperthermia and for LUV-3 with or without hyperthermia were nearly zero. These results confirm earlier findings that LUV-1 and LUV-2 release CDDP almost completely at the heated tumor and that the large DTI value obtained in LUV-1 (DTI = 4.6) was due to its high heat sensitivity and its small systemic clearance.     

氟比洛芬阳离子脂质体温敏凝胶滴眼剂的眼部刺激性和药效学

目的制备氟比洛芬阳离子脂质体温敏凝胶滴眼剂(flurbiprofen cationic liposome thermo-sensitive hydrogel,FCLTH),考察其包封率、胶凝性质、眼部刺激性和药效作用。方法采用乙醇注入-超声法制备氟比洛芬阳离子脂质体,并对其包封率和理化性质等进行了测定。将氟比洛芬阳离子脂质体制备成温敏凝胶滴眼液,考察了FCLTH的胶凝行为、眼部刺激性和药效学。结果氟比洛芬阳离子脂质体包封率可达(84.9±2.75)%,zeta电位为(+33.4±9.68)mV,平均粒径(136±2.98)nm。FCLTH胶凝温度为31.9℃。眼部刺激性实验多次给药后,裂隙灯显微镜观察新西兰兔眼角膜无混浊,虹膜和结膜未见红肿、充血、肿胀等异常现象。组织病理学检查显示,新西兰兔眼7天多次给药后,与空白溶剂相比,给药组组织病理学改变无明显差异。药效学结果显示,FCLTH相对于氟比洛芬滴眼剂对新西兰兔眼急性炎症有抑制作用更强。结论采用乙醇注入-超声法制备的氟比洛芬阳离子脂质体有较高的包封率,且FCLTH在眼部温度下自发形成凝胶,无眼部刺激性,并能够有效抑制眼部炎症作用。     

Development of a bone targeted thermosensitive liposomal doxorubicin formulation based on a bisphosphonate modified non-ionic surfactant

Bone is among the most common sites of metastasis in cancer patients, so it is an urgent need to develop drug delivery systems targeting tumor bone metastasis with the feature of controlled release. This study aimed to delivery of thermosensitive liposomal doxorubicin to bone for tumor metastasis treatment. First, Brij78 (polyoxyethylene stearyl ether) was conjugated with Pamidronate (Pa). By incorporating Pa-Brij78 to DPPC/Chol liposomes, we developed Pa surface functionalized liposomes. The Pa-Brij78/DPPC/Chol liposomes (PB-liposomes) exhibited a stronger binding affinity to hydroxyapatite (HA), a major component of bone, than Brij78/DPPC/Chol liposomes (B-liposomes). Doxorubicin (Dox) was then encapsulated in PB-liposomes and the results demonstrated complete release of Dox from PB-liposomes or the complex of HA/PB-liposomes within 10?min at 42?°C. Next, human lung cancer A549 cells were treated with the thermosensitive complex of HA/PB-liposomes/Dox to mimic tumor bone metastasis treatment through bone targeted delivery of therapeutic agents. Pre-incubation of HA/PB-liposomes/Dox with mild heat at 42?°C induced subsequent higher cytotoxicity to A549 cells than incubation of the same complex at 37?°C, suggesting more active drug release triggered by heat. In conclusion, we synthesized a novel surfactant Pa-Brij78 and it has the potential to be used for development of a bone targeted thermosensitive liposome formulation for treatment of tumor bone metastasis.     

A two-component drug delivery system using Her-2-targeting thermosensitive liposomes

We report on a new method for enhancing the specificity of drug delivery for tumor cells, using thermosensitive immunoliposomes. The liposomes are conjugated to the antibody trastuzumab (Herceptin^®), which targets the human epidermal growth factor receptor 2 (Her-2), a cell membrane receptor overexpressed in many human cancers. Being thermosensitive, the liposomes only release their contents when heated slightly above body temperature, allowing for the possibility of tissue targeting through localized hyperthermia. Using self-quenching calcein, we demonstrate the release of liposome contents into cell endosomes after brief heating to 42°C. To further increase targeting specificity, we incorporate the concept of a two-component delivery system that requires the interaction of two different liposomes within the same endosome for cytoplasmic delivery. Experimental evaluation of the technique using fluorescently labeled liposomes shows that a two-component delivery system, combined with intracellular disruption of liposomes by hyperthermia, significantly increases specificity for Her-2-overexpressing tumor cells.