The effect of monosialylganglioside mix modifying the PEGylated liposomal epirubicin on the accelerated blood clearance phenomenon

PEGylated liposomes are potential candidates to improve the pharmacokinetic characteristics of encapsulated drugs, to extend their circulation half-life and facilitate their passive accumulation at tumour sites. However, PEG-modified liposomes can induce accelerated blood clearance(ABC) upon repeated administration, and the extent of ABC phenomenon on the cytotoxic drugs-containing PEGylated liposomes is related to the dose of the cytotoxic drugs.In this study, EPI served as a model cytotoxic drug, a hydrophilic surfactant molecule,monosialylganglioside(GM1) was chosen and modified on the liposomes together with PEG.It was shown that upon mixed modification, when GM1 contents reached 10% or 15% mol,the ABC phenomenon of the PEGylated liposomal EPI significantly reduced. We also found that GM1 played an important role in abrogating the ABC phenomenon in both the induction phase and the effectuation phase. The results suggested that GM1 incorporation unfortunately did not avoid occurrence of ABC phenomenon completely, but GM1 modification on PEGylated liposomes may provide a significant improvement in clinical practice of PEGylated liposomes. Further study must be necessary.

Mixed PEGylated surfactant modifying system decrease the accelerated blood clearance phenomenon of nanoemulsions in rats

The accelerated blood clearance(ABC) phenomenon which is induced by repeated injection of poly(ethylene glycol)(PEG)-coated colloidal carriers gives clinical challenge to the promising drug delivery system. It is necessary to decrease this unexpected immunological response.A novel 4-arm poly(ethylene glycol-5000)4-cholesteryl methyl amide(4-arm PEG5000-CHMA)has been synthesized. The structure of 4-arm PEG5000-CHMA was confirmed by IR and 1H-NMR spectrum. The pharmacokinetics of the tocopheryl nicotinate(TN)-loaded nanoemulsions modified with 4-arm PEG5000-CHMA or/and 1, 2-distearoyl-Sn-glycero-3-phosphoethanolamine-n-[methoxy(poly-ethyleneglycol)-2000](mPEG2000-DSPE) have been studied. Furthermore, the ABC phenomenon has been detailed investigated in rats by TN-loaded nanoemulsions modified with 4-arm PEG5000-CHMA and mPEG2000-DSPE(CPNE). The plasma levels of TN and anti-PEG IgM antibody were determined by HPLC and ELISA, respectively.The circulation time of the CPNEs were comparable to the mPEG2000-DSPE coated nanoemulsions. Moreover, the ABC phenomenon can be decreased by CPNEs. This study designs a method to decrease the ABC phenomenon and develops a clinical promising nanoemulsion for therapeutic or imaging purpose.

Effect of Kupffer cells depletion on ABC phenomenon induced by Kupffer cells-targeted liposomes

Accelerated blood clearance(ABC) phenomenon is common in many PEGylated nanocarriers, whose mechanism has not been completely elucidated yet. In this study, the correlation between Kupffer cells(KCs) and ABC phenomenon has been studied by KCs-targeted liposomes inducing ABC phenomenon and KCs depletion. In other words, the 4-aminophenyl-α-D-mannopyranoside(APM) lipid derivative DSPE-PEG 2000-APM(DPM), and 4-aminophenyl-β-L-fucopyranoside(APF) lipid derivative DSPE-PEG 2000-APF(DPF) were conjugated and modified on alendronate sodium(AD) liposomes to specifically target and deplete KCs. The dualligand modified PEGylated liposomes(MFPL) showed stronger ability to damage KCs in vitro and in vivo, which also could indirectly illustrate that dual-ligand modification could better target KCs. Besides, the hepatic biodistribution and pharmacokinetics could directly prove that MFPL had a stronger targeting ability to KCs. In addition, in depletion rats, plasma concentration and splenic biodistribution of MFPL and PEGylated liposomes(PL) were significantly elevated and hepatic biodistribution was significantly reduced, which demonstrated that KCs played an important role on elimination of nanoparticles. What’s more, ABC phenomenon of the secondary injection of PL was stronger in KCs depletion rats than that in normal rats, which indicated that depletion of KCs prolonged the circulation of PL in the first injection repeatedly stimulating B-cells in the marginal region of the spleen and causing it to secrete more IgM antibodies. This could also illustrate that anti-PEG IgM takes up a major station compared with KCs. Most important of all, KCs-targeted liposomes could induce a stronger ABC phenomenon than PL in normal rats, which declared that based on the same IgM concentration, the more the KCs were stimulated, the stronger ABC phenomenon was induced. However, in depletion rats, this difference of ABC phenomenon between PL and MFPL could no more exist, further demonstrating that KCs could participate and play a certain role in the ABC phenomenon.

不同相对分子质量PEG-CHMC修饰乳剂对二次注射PE2000诱导产生ABC现象的研究

目的研究比较不同相对分子质量PEG-CHMC修饰乳剂(PEG-CHMC coating emulsion,CHMCE)在大鼠体内的药动学行为及其对二次注射PEG2000-DSPE修饰乳剂(PEG2000-DSPE coating emulsion,PE2000)诱导的ABC现象,探究PEG相对分子质量对乳剂药动学行为及ABC现象的影响。方法以摩尔分数10%PEG修饰密度制备载药乳剂CHMCE和PE,以磷脂剂量5μmol·kg^(-1)进行大鼠尾静脉注射,分别于不同时间点进行静脉取血,处死大鼠后分离肝、脾组织,血浆和组织样品经处理后通过HPLC分析药物含量。结果通过比较药动学参数AUC(0-240 min)、tMRT(0-240 min)可知,高相对分子质量CHMCE(1 000、2 000、5 000)的循环时间较低相对分子质量CHMCE(400、600、800)有所延长,但延长程度不高;CHMCE诱导PE2000产生ABC现象的结果显示,低相对分子质量CHMCE无ABC现象,而高相对分子质量CHMCE诱导了一定强度的ABC现象(CHMCE1000、CHMCE2000和CHMCE5000的ABC index(0-60 min)分别为0.64、0.59和0.53)。结论 PEG相对分子质量在CHMCE的药动学行为及ABC现象的产生中具有重要影响,研究结果对PEG相对分子质量在ABC现象中的影响规律进行了补充,为PEG化制剂相对分子质量的选择提供了一定借鉴。

PEG化脂质体30周年回顾与反思

目的 回顾PEG化脂质体(PEGylated liposomes)首次报道至今30年来的相关研究,反思其临床安全性和有效性。方法 查阅国内外相关文献137篇,归纳、总结和分析PEG化脂质体的利弊。结果 聚乙二醇(polyethylene glycol, PEG)的修饰成功地延长了脂质体的血液循环时间,并且广泛应用于临床。目前,多种PEG化脂质体如ThermoDox^(■)、Lipoplatin^(TM)和MM-302等处于临床试验阶段。然而,研究表明,PEG化制剂可以诱导抗-PEG抗体的产生,抗-PEG抗体与临床上补体激活相关假变态反应(complement activation related pseudo allergy, CARPA)的发生密切相关。更严重的是,抗-PEG抗体在健康汉族人血液样本中的阳性检测率高达72%,已成为PEG化制剂临床应用面临的主要问题。结论 PEG化脂质体并不完美,已在人群中普遍存在的抗-PEG抗体会降低临床PEG化制剂的用药安全性和有效性,应该引起重视。