188Re-Herceptin-磁性纳米微粒的体外抗肿瘤作用

目的探讨^188Re—Herceptin-磁性纳米微粒在外置磁场下对HER-2／neu癌基因高表达的SKBR-3乳腺癌细胞的靶向结合性及抗癌作用。方法采用戊二醛交联法使人源性单克隆抗体Her—ceptin与磁性纳米微粒交联，用直接标记法制备^188Re—Herceptin及^188Re—Herceptin-磁性纳米微粒，用羰基铼标记法制备^188Re-磁性纳米微粒。肿瘤细胞体外抑制实验设4个组：^188Re—Herceptin-磁性纳米微粒组、^188Re—Herceptin组、^188Re-磁性纳米微粒组和^188ReO4^-组，各组均设3．7×10^4、18．5×10^4、37×10^4、55．5×10^4、74×10^4Bq／ml5个放射性剂量级别；另设生理盐水对照组。采用四甲基偶氮唑蓝（MTT）法测定各组的抑瘤效应，计算相对抑制率，采用半数抑制放射性浓度（IC50）对各组抑瘤作用进行比较和评价。结果^188Re—Herceptin-磁性纳米微粒和^188Re—Herceptin组对SKBR-3细胞均有较强杀伤作用，且呈剂量依赖性；而^188Re-磁性纳米微粒和^188Re04组的杀伤作用较弱0188Re—Herceptin-磁性纳米微粒组的IC50（53．1×10^4Bq／L）明显低于^188Re—Herceptin组（76．1×10^4Bq／L）；^188Re一磁性纳米微粒组和^188ReO4组的IC50分别为169×10^4和175×10^4Bq／L，明显高于前2组。结论^188Re—Herceptin-磁性纳米微粒和^188Re—Herceptin均可明显抑制体外培养的SKBR-3乳腺癌细胞增殖，且前者的抑制作用较后者强。     

188Re标记免疫靶向磁性纳米微粒及其生物学分布

目的研究^188Re标记具有HER-2／neu癌基因靶向特异性的Herceptin免疫磁性纳米微粒及其在小鼠体内的生物学分布。方法利用戊二醛作为交联剂，将人源性单克隆抗体Herceptin与化学修饰的磁性纳米微粒进行连接，构建免疫磁性纳米微粒。采用直接标记法将^188Re标记到免疫磁性纳米微粒上。采用羰基铼标记法，以fac-[^188Re（CO）3（H2O）3]^＋作为放射性标记前体，对表面固载组氨酸的磁性纳米微粒进行标记。分别测定所制备^188Re标记物的标记率和体外稳定性及免疫磁性纳米微粒的单克隆抗体免疫活性，并观察^188Re标记的磁性纳米微粒及免疫磁性纳米微粒的小鼠体内生物分布。结果经扫描电镜证实免疫磁性纳米微粒的单个粒径大小平均为60nm，而表面固载组氨酸的磁性纳米微粒的粒径平均为30nm。^188Re对Herceptin、免疫磁性纳米微粒及固载组氨酸的磁性纳米微粒的标记率均〉90％，在小牛血清中具有良好的体外稳定性，并且磁性纳米微粒上连接的单克隆抗体仍保持较高的免疫活性。小鼠体内分布实验显示^188Re标记的磁性纳米微粒及免疫磁性纳米微粒在血液中有较高的放射性分布且血循环时间较长，同时两者在肝内均有较多的摄取。结论^188Re标记的磁性纳米微粒及免疫磁性纳米微粒在体外及动物体内较稳定，无明显的^188Re脱落。可用于下一步荷瘤裸鼠体内的研究。     

188Re-奥曲肽在荷瘤裸鼠体内分布的实验研究

目的研究188Re-奥曲肽在荷瘤裸鼠体内的分布,为进一步肿瘤靶向治疗奠定基础.方法16只荷人H460非小细胞肺癌的BALB/c裸鼠分为4组,经尾静脉注射188Re-奥曲肽18.5MBq(0.2ml),于注射后2h,4h,24h,48h每个时间点处死一组裸鼠,取血液、肿瘤组织及主要脏器测量其放射性计数率值,经放射性衰变校正后计算每克组织的百分注射剂量率(%ID/g),观察标记物在动物体内的生物学分布.另2只荷瘤裸鼠同样尾静脉注射相同剂量的188Re-奥曲肽,于注射后相同时间点行SPECT扫描,利用感兴趣区技术对肿瘤/非瘤组织放射性比值(T/NT)进行半定量分析.结果188Re-奥曲肽标记率达(95.3±1.8)%,188Re-奥曲肽在荷瘤裸鼠体内主要分布于肿瘤组织、肝脏、肾脏及肠道,肿瘤部位在4h摄取达到高峰9.8%ID/g,此时SPECT在肿瘤部位有明显的放射性核素浓聚,T/NT在尾静脉药物注射后24h达到高值为7.1.结论188Re-奥曲肽在BALB/c荷瘤裸鼠体内对人非小细胞肺癌具有靶向定位作用,其在肿瘤部位的分布具有较高的T/NT,188Re-奥曲肽有望用于表达生长抑素受体肿瘤的核素靶向治疗.     

心脏肾上腺素能神经的PET应用

目的研究188Re-奥曲肽在荷瘤裸鼠体内的分布,为进一步肿瘤靶向治疗奠定基础。方法16只荷人H460非小细胞肺癌的BALB／c裸鼠分为4组,经尾静脉注射188Re-奥曲肽 18．5MBq(O．2ml)．于注射后2h,4h,24h,48h每个时间点处死一组裸鼠,取血液、肿瘤组织及主要脏器测量其放射性计数率值,经放射性衰变校正后计算每克组织的百分注射剂量率(％ID／g),观察标记物在动物体内的生物学分布。另2只荷瘤裸鼠同样尾静脉注射相同剂量的188Re-奥曲肽,于注射后相同时间点行SPECT扫描,利用感兴趣区技术对肿瘤／非瘤组织放射性比值(T／NT)进行半定量分析。结果188Re-奥曲肽标记率达(95．3±1．8)％,188Re-奥曲肽在荷瘤裸鼠体内主要分布于肿瘤组织、肝脏、肾脏及肠道,肿瘤部位在4h摄取达到高峰9．8％ID/g,此时SPECT在肿瘤部位有明显的放射性核素浓聚,T／NT在尾静脉药物注射后24h达到高值为7．1。结论 188Re-奥曲肽在BALB／c荷瘤裸鼠体内对人非小细胞肺癌具有靶向定位作用,其在肿瘤部位的分布具有较高的T／NT,188Re．奥曲肽有望用于表达生长抑素受体肿瘤的核素靶向治疗。     

[188Re(CO)3(H2O)3]+间接标记免疫磁性纳米微粒的实验研究

目的探讨标记单克隆抗体磁性纳米微粒的实验条件。方法以[二（2-吡啶甲基）-氨基]-乙酸（PADA）作为双功能螯合剂，将[^188Re（CO）3（H2O）3]^＋间接标记到耦联了单克隆抗体的磁性纳米微粒。结果[^188Re（CO）3（H2O）3]^＋间接标记免疫磁性纳米微粒的标记率大于80％，在小牛血清和生理盐水中48h后稳定性仍能保持在90％以上。结论使用PADA作为双功能螯合剂，[^188Re（CO）3（H2O）3]^＋间接标记免疫磁性纳米微粒的标记率高，稳定性好，适于进一步体内研究。     

磁共振检测纳米磁靶向性药物在荷瘤小鼠体内分布的初步研究

目的:利用MRI技术探讨活体状态磁靶向性药物在荷瘤小鼠体内的分布.方法:取荷瘤裸鼠24只随机分为3组,每组8只.A组为空白对照组,经尾静脉注射生理盐水0.2 ml;B组未建立局部磁场,单纯静脉注射纳米磁小体靶向氟脲嘧啶药囊(剂量250 mg/kg);C组为建立肿瘤局部内磁场后静脉注射纳米磁小体靶向氟脲嘧啶药囊(250 mg/kg).三组每天用药一次,连续5天.在最后一次用药后24 h,每组各取2只动物行MRI扫描,扫描完毕后处死荷瘤鼠,取肝、肾、脑和肿瘤组织作病理学检查.结果:与A组比较,B和C组中T1WI和T2WI上肝、肾组织信号都明显降低,以肝脏降低更显著;与A和B组比较,C组中肿瘤信号在T2WI上明显降低;3组中,脑组织信号均无明显变化.病理学检查也进一步证实.结论:磁性药物主要通过肝、肾代谢,在建立肿瘤局部内磁场后,磁性药物可以靶向性分布于肿瘤,磁性药物不能通过血脑屏障.MRI技术是检测磁靶向性药物在活体荷瘤小鼠体内分布的有效方法.     

HMME介导的光动力疗法诱导人肝癌细胞SMMC-7721凋亡的实验研究

目的:探讨光动力疗法对肝癌细胞SMMC-7721凋亡的影响。方法:以血卟啉单甲醚(HMME)为光敏剂,波长635nm激光为激发光源的光动力疗法作用于肝癌SMMC-7721细胞。细胞分别与浓度5、10、20、30μg/ml的光敏剂孵育4h后,用不同能量密度的激光照射。MTT法检测HMME的暗毒性以及光动力疗法作用24h后的细胞活性。Hoechst细胞     

红景天甙对人肝癌细胞c-myc表达的逆转作用

目的:研究红景天甙对人肝癌细胞系SMMC-7721的c-myc表达的逆转作用。方法:通过不同剂量红景天甙处理体外培养的SMMC-7721细胞株,采用免疫组织化学检测细胞c-myc表达。结果:不同终浓度(0.5mg/ml、1.0mg/ml、1.5mg/ml)的红景天甙均能抑制SMMC-7721细胞C-myc表达,抑制率分别为8.8%、21.6%和39.8%(P<0.01)。其抑制作用呈剂量效应正相关。结论:红景天甙可抑制SMMC-7721细胞内c-myc的表达,提示其在体外诱导肝癌细胞分化的可能。     

188Re-Hepama-1单克隆抗体荷人肝癌裸鼠模型实验研究

目的 研究188Re-单克隆抗体(简称单抗)Hepama-1在荷人肝癌裸鼠体内生物学分布及肿瘤抑制,为放免治疗提供依据.方法 制备188Re-Hepama-1并测定其标记率及体外稳定性.将40只荷瘤裸鼠用完全随机法分为5组:生理盐水对照组、188ReO4-瘤内注射组、188Re标记健康小鼠IgG(188Re-mIgG)瘤内注射组、188Re-Hepama-1静脉给药组、188Re-Hepama-1瘤内注射组.注射后48 h每组各处死3只,测定肿瘤和肝等重要器官的放射性,用每克组织百分注射剂量率(%ID/g)表示;分别于治疗后1,2,3及4周计算肿瘤体积,与治疗前肿瘤体积进行对比;治疗后4周,每组各处死3只荷瘤裸鼠,观察肿瘤细胞超微结构改变及组织病理学改变.结果 188Re-Hepama-1标记率为85%,放化纯＞95%.注射后48h瘤内注射188Re-Hepama-1组肿瘤组织放射性摄取为11.53%ID/g,静脉注射188Re-Hepama-1组为2.79%ID/g;而瘤内注射188Re-Hepama-1组血、肝、肾等组织摄取均＜1.00%ID/g,明显低于静脉注射188R-Hepama-I组(均＞1.50%ID/g);静脉注射188Re-Hepama-1组和瘤内注射188Re-Hepama-1组的肿瘤体积与188ReO4-组及188Re-mIgG组的差异均具有统计学意义(P均＜0.05).形态学观察可见瘤内注射188Re-Hepama-1组和静脉注射188Re-Hepama-1组细胞凋亡,凋亡小体及变性坏死增多,而其余组少见.结论 静脉注射和瘤体内注射188Re-Hepama-1对裸鼠模型肝癌具有较好的治疗效应.静脉注射188Re-Hepama-1在临床肝癌的导向治疗方面有较好的应用前景.     

基于ST68微泡的磁靶向控释载体的制备及性能研究

目的 构建具有超声和磁场双重响应特性的磁性微泡.方法 采用声振空化法制备基于表面活性剂的微泡超声造影剂(ST68),用多元醇法制备表面带负电荷的磁性Fe3O4纳米粒子.以微泡为模板,通过静电吸引层层自组装的方法使聚乙烯亚胺和磁性Fe3O4纳米粒子在微泡表面交替沉积,制备磁性微泡.搭建体外超声造影装置,对比注入磁性微泡(3×108个/ml)前后装置中硅胶管的超声图像,并观察对硅胶管施加磁场后磁性微泡的运动情况.对比注入磁性微泡前后新西兰大白兔肾脏的超声图像,以评价磁性微泡的体内超声造影效果.结果 制得的Fe3O4纳米粒子表面带有稳定的负电荷(-24.6±6.7)mV,组装得到的磁性微泡中超过98％的微泡粒径小于8μm,满足对超声造影剂大小的基本要求.注入磁性微泡前,硅胶管无回声信号;注入磁性微泡后,硅胶管内呈实性回声;施加磁场后,磁性微泡向磁场方向定向迁移.兔体内超声造影结果示推注磁性微泡前,超声图像不能显示肾;推注后肾脏影清晰.结论 制备的磁性微泡磁靶向和超声造影效果良好,为进一步研究具有诊断和治疗双重作用的磁靶向微泡超声造影剂打下了基础.     

188Re-胰岛素样生长因子1类似物在荷人胰腺癌裸鼠体内分布及其显像研究

目的 研究188Re标记胰岛素样生长因子l类似物(IGF-1A)在荷人胰腺癌裸鼠体内的分布及其显像.方法 ①直接法标记188Re-IGF-1A并测定标记率.②建立荷人胰腺癌Patu8988裸鼠模型.③188Re-IGF-1A经瘤内注射荷人胰腺癌裸鼠瘤内,分别于注射后15 min、1 h、4 h、24 h、3 d、5 d进行SPECT平面显像.④188ReO4-经瘤内注射后15 min、1 h、2 h、4 h、24 h进行显像,取各时间组裸鼠(n=4)脏器和肿瘤组织,计算每克组织百分注入剂量(%ID/g)及肿瘤/非肿瘤组织放射性摄取比值(T/NT).结果 ①188Re-IGF-1A标记率为(94.07±0.32)%.②瘤内注射188Re-IGF-1A后,肿瘤部位放射性积聚量4 h内差异无统计学意义(F=1.622,P＞0.05),且随时间延长,肿瘤与其他脏器的T/NT呈上升趋势,其中肿瘤/肌肉在5 d时最高,达到6531.79±4930.26.③瘤内注射188ReO4-后,在体内初始主要分布于甲状腺、胃、肿瘤、血液,随时间延长,肿瘤部位放射性计数迅速下降.④在24 h,瘤内注射188Re-IGF-1A组肿瘤及肾脏内%ID/g较188ReO4-组高,两者有统计学差异(t=5.877,t=13.287,P＜0.01);两组肿瘤内%ID/g比值在24 h达到最高,为74.10倍.⑤瘤内注射188Re-IGF-1A后,SPECT平面显像见瘤内浓聚,5 d时仅见肿瘤部位显影.结论 188Re-IGF-1A对胰腺癌具有良好的亲和力,在肿瘤部位有较高的T/NT,可望作为胰腺癌治疗的药物.     

Lipiodol solution of 188Re-HDD as a new therapeutic agent for transhepatic arterial embolization in liver cancer: preclinical study in a rabbit liver cancer model.

It has been reported that lipiodol solution of (188)Re-labeled 2,2,9,9-tetramethyl-4,7-diaza-1,10-decanedithiol (TDD), an N(2)S(2) derivative, shows excellent targeting of liver cancer after transhepatic arterial embolization (TAE). However, its tumor retention is not high enough to treat liver cancer. Therefore, a new form of TDD, 4-hexadecyl-TDD (HDD), was developed to improve tumor retention by introducing a long alkyl chain. In this study, we compared the tumor retention properties of (188)Re-HDD/lipiodol and (188)Re-TDD/lipiodol, using a rabbit liver cancer model, and performed dosimetry using the results. METHODS: The VX2 cancer cell line was implanted into the livers of 7 rabbits. TAE was performed on 3 rabbits with (188)Re-TDD/lipiodol and on 4 rabbits with (188)Re-HDD/lipiodol, and conjugated anterior and posterior planar scans were obtained at 1, 2, 6, 24, and 48 h after TAE. From these images, tumor retention was calculated and compared between (188)Re-TDD and (188)Re-HDD. Afterward, the required dose of radioactivity and the radiation dosimetry for exposure of major organs were calculated using MIRDOSE3.1 software. RESULTS: The residence times of radioactivity in the liver were 10.2 +/- 1.0 h in the (188)Re-TDD group and 17.6 +/- 0.8 h in the (188)Re-HDD group (P = 0.034). The required radioactivity for 100 Gy of irradiation to 2.64- to 5.27-cm tumors was 142-1,070 MBq of (188)Re-HDD in the rabbit model. The radiation exposures for the major organs were within the tolerable range, and the S-value for the whole body (effective dose equivalent) was calculated to be 0.209 mSv/MBq. CONCLUSION: Introduction of a long alkyl chain significantly improved the tumor retention of (188)Re-HDD/lipiodol, compared with that of (188)Re-TDD/lipiodol. Moreover, the required radioactivity for humans and the radiation exposure were within the feasible range for clinical application.     

Preclinical evaluation of isostructural Tc-99m- and Re-188-folate-Gly-Gly-Cys-Glu for folate receptor-positive tumor targeting

Objective

The purpose of the present study was to prepare isostructural Tc-99m- and Re-188-folate-Gly-Gly-Cys-Glu (folate-GGCE), and to evaluate the feasibility of their use for folate receptor (FR)-targeted molecular imaging and as theranostic agents in a mouse tumor model.

Methods

Folate-GGCE was synthesized using solid-phase peptide synthesis and radiolabeled with Tc-99m or Re-188. Radiochemical characterization was performed by radio-high-performance liquid chromatography. The biodistribution of Tc-99m-folate-GGCE was studied, with or without co-injection of excess free folate, in mice bearing both FR-positive (KB cell) and FR-negative (HT1080 cell) tumors. Biodistribution of Re-188-folate-GGCE was studied in mice bearing KB tumors. Serial planar scintigraphy was performed in the dual tumor mouse model after intravenous injection of Tc-99m-folate-GGCE. Serial micro-single photon emission computed tomography/computed tomography (SPECT/CT) studies were performed, with or without co-injection of excess free folate, in the mouse tumor model after injection of Tc-99m-folate-GGCE or Re-188-folate-GGCE.

Results

The radiolabeling efficiency and radiochemical stability of Tc-99m- and Re-188-folate-GGCE were more than 95 % for up to 4 h after radiolabeling. Uptake of Tc-99m-folate-GGCE at 1, 2, and 4 h after injection in KB tumor was 16.4, 23.2, and 17.6 % injected dose per gram (%ID/g), respectively. This uptake was suppressed by 97.4 % when excess free folate was co-administered. Tumor:normal organ ratios at 4 h for blood, liver, lung, muscle, and kidney were 54.3, 25.2, 38.3, 97.8, and 0.3, respectively. Tumor uptake of Re-188-folate-GGCE at 2, 4, 8, and 16 h after injection was 17.4, 21.7, 24.1, and 15.6 %ID/g, respectively. Tumor:normal organ ratios at 8 h for blood, liver, lung, muscle, and kidney were 126.8, 21.9, 54.8, 80.3, and 0.4, respectively. KB tumors were clearly visualized at a high intensity using serial scintigraphy and micro-SPECT/CT in mice injected with Tc-99m- or Re-188-folate-GGCE. The tumor uptake of these molecules was completely suppressed when excess free folate was co-administered.

Conclusion

Isostructural Tc-99m- and Re-188-folate-GGCE showed high and FR-specific uptake by tumors and generally favorable tumor:normal organ ratios. The tumor targeting capabilities of Tc-99m- and Re-188-folate-GGCE were clearly evident on serial imaging studies. This isostructural pair may have potential diagnostic and theranostic applications for FR-positive tumors.

     

Biokinetic and dosimetric studies of Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical.

Methods

¹⁸⁸Re-HA was prepared by a direct labelling method to produce a ReO(O-COO)₂-type coordination complex. ¹⁸⁸Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of ¹⁸⁸Re-HA was determined.

Results

A stable complex of ¹⁸⁸Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T_1/2α=21 min). Four hours after administration, ¹⁸⁸Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47±5.11% of the injected dose). The liver MTD in mice was 40 Gy after 7.4 MBq of ¹⁸⁸Re-HA injection.

Conclusions

¹⁸⁸Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.     

A comparative study of 188Re(V)-meso-DMSA and 188Re(V)-rac-DMSA: preparation and in vivo evaluation in nude mice xenografted with a neuroendocrine tumor

Dimercaptosuccinic acid (DMSA) exists in meso and racemic (rac) forms. Unlike a meso isomer, rac-2,3-DMSA is very soluble in water, strongly acidic solutions and organic solvents. Despite these differences, rac-2,3-DMSA has not been studied as a radiopharmaceutical. In this study, ¹⁸⁸Re complexes with diastereomeric DMSA were prepared to compare the properties of ¹⁸⁸Re(V)-rac-DMSA with those of ¹⁸⁸Re(V)-meso-DMSA in in vitro and in vivo models.

Methods

rac-2,3-DMSA was synthesized and radiolabeled with ¹⁸⁸Re. The biodistribution and gamma camera imaging of ¹⁸⁸Re(V)-meso-DMSA and ¹⁸⁸Re(V)-rac-DMSA were performed in nude mice subcutaneously implanted with PC-12 cell lines.

Results and conclusions

Both ¹⁸⁸Re(V)-meso-DMSA and ¹⁸⁸Re(V)-rac-DMSA showed excellent radiochemical purity and stability at room temperature. Compared with ¹⁸⁸Re(V)-meso-DMSA, ¹⁸⁸Re(V)-rac-DMSA needed a higher concentration of rac-DMSA and metabisulfite for maximum yields. ¹⁸⁸Re(V)-meso-DMSA showed high labeling efficiency at pH 2, whereas ¹⁸⁸Re(V)-rac-DMSA showed maximum yields at pH 5. The tumor uptake of ¹⁸⁸Re(V)-rac-DMSA was 3.5 times higher than that of ¹⁸⁸Re(V)-meso-DMSA at 1 h (P<.01). Gamma camera images showed that ¹⁸⁸Re(V)-rac-DMSA was more selectively localized than ¹⁸⁸Re(V)-meso-DMSA at the tumor region in a xenograft model. These results demonstrate that ¹⁸⁸Re(V)-rac-DMSA may have better potential than ¹⁸⁸Re(V)-meso-DMSA as a therapeutic agent against neuroendocrine tumors.     

Cell culture and xenograft-bearing animal studies of radiolabeled antisense DNA carrier nanoparticles with streptavidin as a linker.

Transmembrane transfectors (carriers) are increasingly being viewed as helpful or even necessary to improve cellular delivery in connection with antisense tumor targeting and other applications requiring cell membrane transport of DNAs, RNAs, and other oligomers. We are investigating streptavidin as a convenient linker for biotinylated carriers and oligomers because it requires only simple mixing for preparation. The goal of this study was to evaluate antisense DNA-streptavidin-carrier nanoparticles for accumulation in cell culture and in xenograft-bearing mice. METHODS: The 3 carriers were cholesterol, a 10-mer Tat peptide, and a 10-mer polyarginine peptide. A 20-mer DNA targeting the mdr1 messenger RNA coding for Pgp expression was used as the phosphodiester (PO) DNA as well as the phosphorothioate (PS) DNA. In all cases, the (99m)Tc radiolabel was on the DNA. The 8 nanoparticles were first tested in mdr1(++) KB-G2 and TCO-1 cells and in mdr1(+/-) KB-31 cells in culture for evidence of improved accumulation and antisense targeting. Thereafter, the PS DNA-streptavidin-Tat, PO DNA-streptavidin-Tat, and PS DNA-streptavidin-cholesterol nanoparticles were administered intravenously to KB-G2 xenograft-bearing mice, and tissue distributions were measured. RESULTS: In culture, the PO nanoparticles showed increased accumulation compared with the corresponding nanoparticles without the carrier in all 3 cell types; in contrast, with the PS nanoparticles, any similar carrier-mediated increase may have been obscured by the much higher protein-binding affinity of PS DNA. As evidence of antisense targeting, the Tat and cholesterol PS nanoparticles showed statistically significant accumulation at 23 h in cells in the descending order TCO-1, KB-G2, and KB-31, although there were no significant differences among the PO nanoparticles. In xenograft-bearing mice, the tissue accumulation of both forms of the PS nanoparticles greatly exceeded that of the PO nanoparticles and, including in the tumor, were similar to that obtained previously for naked PS DNA. CONCLUSION: The presence of the streptavidin linker had no obvious detrimental effect on the functions of the carriers and antisense DNAs. The higher protein-binding affinity of the PS nanoparticles than the PO nanoparticles was still apparent both in vitro and in vivo, the pharmacokinetics of the PS nanoparticles were similar to that of naked PS DNA, and the carriers improved cellular accumulation, at least for the PO nanoparticles. These observations, taken together with the higher accumulation of both forms of the antisense PS nanoparticles in mdr1(++) KB-G2 and TCO-1 cells than in mdr1(+/-) KB-31 cells, suggest that further effort is justified to confirm that the antisense properties of the DNAs were not compromised by the presence of streptavidin.     

Biodistribution, pharmacokinetics and imaging of (188)Re-BMEDA-labeled pegylated liposomes after intraperitoneal injection in a C26 colon carcinoma ascites mouse model

Nanoliposomes are important carriers capable of packaging drugs for various delivery applications through passive targeting tumor sites by enhanced permeability and retention effect. Radiolabeled liposomes have potential applications in radiotherapy and diagnostic imaging. The purpose of this study was to investigate the biodistribution, pharmacokinetics and imaging of nanotargeted (188)Re-N,N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA)-labeled pegylated liposomes (RBLPL) and unencapsulated (188)Re-BMEDA after intraperitoneal (ip) injection in a C26 colon carcinoma ascites mouse model. The nanopegylated liposomes were labeled with (188)Re-BMEDA. The labeling efficiency of RBLPL was 82.3+/-4.5%. In vitro stability of RBLPL in normal saline at room temperature and in rat plasma at 37 degrees C for 72 h was 92.01+/-1.31% and 82.4+/-1.64%, respectively. The biodistribution studies indicated that the radioactivity in ascites was 69.96+/-14.08 percentage injected dose per gram (% ID/g) at 1h to 5.99+/-1.97% ID/g at 48 h after ip administration of RBLPL. The levels of radioactivity in tumor were progressive accumulation to a maximum of 6.57+/-1.7% ID/g at 24 h. The radioactivity of (188)Re-BMEDA in ascites reached the maximum level of 54.89+/-5.91% ID/g at 1 h and declined rapidly with time. Pharmacokinetic studies revealed that the terminal half-life, total body clearance and area under the curve of RBLPL were 5.3-, 9.5- and 9.4-fold higher than that of (188)Re-BMEDA in blood, respectively. These results suggested that the long circulation, bioavailability and localization of RBLPL in tumor and ascites sites, which also demonstrate that the ip administration of RBLPL is a potential multifunctional nanoradiotherapeutics and imaging agents on a C26 colon carcinoma ascites mouse model.