TARGETABILITY OF NOVEL IMMUNOLIPOSOMES MODIFIED WITH AMPHIPATHIC POLY(ETHYLENE GLYCOL)S CONJUGATED AT THEIR DISTAL TERMINALS TO MONOCLONAL-ANTIBODIES
TARGETABILITY OF NOVEL IMMUNOLIPOSOMES MODIFIED WITH AMPHIPATHIC POLY(ETHYLENE GLYCOL)S CONJUGATED AT THEIR DISTAL TERMINALS TO MONOCLONAL-ANTIBODIES
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DOI：
10.1016/0005-2736(94)00263-o
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发表时间：
1995-03-08
影响因子：
3.4
通讯作者：
IWATSURU, M
中科院分区：
文献类型：
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作者：
MARUYAMA, K;TAKIZAWA, T;IWATSURU, M
新合成了二硬脂酰基-N-(3-羧丙酰基聚乙二醇丁二醇基)磷脂酰乙醇胺(DSPE-PEG-COOH)，并用于制备新型的在聚乙二醇链末端携带单抗的免疫脂质体(C型)。以卵磷脂酰胆碱(EPC)和胆固醇(CH)(2：1，m/m)为原料，加入6mol%的DSPE-PEG-COOH制备脂质体，并将一种对肺内皮细胞具有高度特异性的单抗34A偶联到DSPE-PEG-COOH的羧基上，得到不同量的抗体分子。制备其他有聚乙二醇包被(B型)或无聚乙二醇包被(较早类型的免疫脂质体，A型)的免疫脂质体以供比较。B型和C型免疫脂质体中聚乙二醇酯的平均相对分子质量为2000。无抗体的B型和C型脂质体由于聚乙二醇组分的存在，循环时间延长，网状内皮系统(RES)摄取减少。这三种不同类型的34A免疫脂质体每个囊泡含有30-35个抗体分子，注射到小鼠体内，以测试其对肺的免疫靶向性。34A-B型的肺结合效率仅为34A-A型的一半，但大量34A-B型长期滞留在血液循环中，表明聚乙二醇链的空间位阻不仅减少了免疫特异性抗体与抗原的结合，而且还减少了RES的摄取。34A-C型的肺结合度约为34A-A型的1.3倍，表明结合在聚乙二醇端的抗体的识别没有空间上的阻碍，而游离的聚乙二醇酯(即不携带抗体的聚乙二醇酯)通过使免疫脂质体逃避RES摄取而有效地提高了免疫脂质体的血药浓度。后一种现象被非特异性抗体-C型免疫脂质体(14-C型)证实，该脂质体长期显示出较高的血液水平。我们的方法提供了一种简单的方法，将抗体直接结合到已经结合到脂质体膜上的聚乙二醇远端，并应有助于开发用于诊断和治疗的更好的靶向药物载体。
Distearoyl-N-(3-carboxypropionoyl poly(ethylene glycol) succinyl)phosphatidylethanolamine (DSPE-PEG-COOH) was newly synthesized and used to prepare novel immunoliposomes carrying monoclonal antibodies at the distal ends of the PEG chains (Type C). Liposomes were prepared from egg phosphatidylcholine (ePC) and cholesterol (CH) (2:1, m/m) containing 6 mol% of DSPE-PEG-COOH, and a monoclonal IgG antibody, 34A, which is highly specific to pulmonary endothelial cells, was conjugated to the carboxyl groups of DSPE-PEG-COOH to give various amounts of antibody molecules per liposome. Other immunoliposomes with PEG coating (Type B) or without PEG coating (an earlier type of immunoliposome, Type A) were prepared for comparison. The average molecular weight of PEG in Type B or C immunoliposomes was 2000. Type B and Type C liposomes without antibodies showed prolonged circulation time and reduced reticulo-endothelial system (RES) uptake owing to the presence of PEG. These three different types of 34A-immunoliposomes with 30-35 antibody molecules per vesicle were injected into mice to test the immunotargetability to the lung. The efficiency of lung binding of 34A-Type B was one-half of that of 34A-Type A, though a large amount of 34A-Type B remained in the blood circulation for a long time, suggesting that the steric hindrance of PEG chains reduced not only the immunospecific antibody-antigen binding, but also the RES uptake. The degree of lung binding of 34A-Type C was about 1.3-fold higher than that of 34A-Type A, indicating that recognition by the antibodies attached to the PEG terminal was not sterically hindered and that the free PEG (i.e., that not carrying antibody) was effective in increasing the blood concentration of immunoliposomes by enabling them to evade RES uptake. The latter phenomenon was confirmed by using nonspecific antibody-Type C immunoliposomes (14-Type C), which showed a high blood level for a long time. Our approach provides a simple means of conjugating antibodies directly to the distal end of PEG which is already bound to the liposome membrane, and should contribute to the development of superior targetable drug delivery vehicles for use in diagnostics and therapy.