叶酸靶向紫杉醇聚合物纳米囊泡的制备及其抗肿瘤活性研究

 目的 制备新型叶酸靶向紫杉醇聚合物纳米囊泡，研究其理化性质、细胞毒性和体内抗肿瘤活性。方法 以两亲性三嵌段共聚物聚己内酯-b-聚乙二醇-b-聚己内酯（PCL-b-PEG-b-PCL）、甲氧基聚乙二醇二硬脂酰磷脂酰乙醇胺（mPEG2000-DSPE）、偶联叶酸的磷脂DSPE-PEG(2000) Folate共混物为载体材料，通过薄膜-超声分散法制备出叶酸靶向紫杉醇聚合物纳米囊泡并对其进行形态、粒径及其分布、Zeta电位、载药量及包封率、体外释放等表征，用CCK-8法研究了聚合物纳米囊泡对H1299肺癌细胞的细胞毒性，并评价其在BALB/c小鼠EMT-6乳腺癌模型中的抗肿瘤效果。结果 叶酸靶向紫杉醇聚合物纳米囊泡呈球形，具有明显的核-壳结构，粒径均匀。随着紫杉醇投药量的增加，纳米囊泡的粒径增大，包封率降低。载药30%的叶酸靶向紫杉醇聚合物纳米囊泡的平均粒径为311 nm，多分散系数为0.171，Zeta电位为-30.3 mV，包封率为91.16%。体外释放研究表明，载紫杉醇聚合物纳米囊泡基本无药物突释现象，具有缓释特性。细胞毒性研究表明，当紫杉醇浓度为25 μg·mL-1时，叶酸靶向紫杉醇聚合物纳米囊泡的细胞毒性低于相应浓度的紫杉醇/聚氧乙烯蓖麻油注射剂。体内抗肿瘤活性实验研究表明，叶酸靶向紫杉醇聚合物纳米囊泡对小鼠EMT-6乳腺癌具有明显抑制作用，具有与紫杉醇/聚氧乙烯蓖麻油注射剂相似的抑制肿瘤作用。结论 叶酸靶向紫杉醇聚合物纳米囊泡具有高载药量及包封率、均匀的粒径及分布、缓释特性、低毒和较好的抗肿瘤作用，是一种有潜力的紫杉醇缓控释新剂型用于提高紫杉醇的药效并且降低不良反应。

Preparation, Characterization, in Vitro and in Vivo Studies on Folate-Targeted Biodegradable Polymersomes Loaded with Paclitaxel

OBJECTIVE To prepare folate-targeted biodegradable polymersomes loaded with paclitaxel, evaluate its physical and chemical properties, in vitro cell cytotoxicity as well as in vivo antitumor activity. METHODS Folate-targeted biodegradable paclitaxel-loaded polymersomes composed of PCL-b-PEG-b-PCL， mPEG2000-DSPE and DSPE-PEG(2000) Folate were prepared by thin-film hydration and ultrasonic method, and characterized in terms of morphology, particle size and size distribution, drug loading content, encapsulation efficiency and in vitro release. The cell cytotoxicity of folate-targeted biodegradable paclitaxel-loaded polymersomes in lung carcinoma H1299 cells was observed with CCK-8 assay. The in vivo antitumor activity was evaluated in BALB/c mice bearing the EMT-6 breast tumor models. RESULTS Folate-targeted biodegradable paclitaxel-loaded polymersomes showed spherical core-shell morphology with narrow size distribution. With the increase of drug amount, the sizes of folate-targeted biodegradable paclitaxel-loaded polymersomes increased, while the drug encapsulating efficiency decreased. The folate-targeted biodegradable paclitaxel-loaded polymersomes with 30% drug-loading content were found as spherical shape with the average particle diameter of 311 nm, polydispersity coefficient of 0.171 and Zeta potential of -30.3 mV. The folate-targeted biodegradable paclitaxel-loaded polymersomes showed a continuous and steady release of PTX without initial burst release. At the paclitaxel concentration of 25 μg·mL-1, the folate-targeted biodegradable paclitaxel-loaded polymersomes displayed much less cell cytotoxicity than paclitaxel injections with Cremophor EL. The in vivo tumor inhibiting activity of folate-targeted biodegradable paclitaxel-loaded polymersomes was similar to that of paclitaxel injections with Cremophor EL in the same paclitaxel concentration. CONCLUSION The folate-targeted biodegradable paclitaxel-loaded polymersomes had high drug-loading content and drug encapsulating efficiency, more uniform size and size distribution, excellent drug sustainable-release behavior, less cytotoxicity, good antitumor activity similar to paclitaxel injections with Cremophor EL. Therefore, folate-targeted biodegradable paclitaxel-loaded polymersomes would be a novel paclitaxel preparation in clinic for the treatment of tumor.