Ogihara-Umeda I, Sasaki T, Nishigori H
Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
Eur J Nucl Med. 1993 Feb;20(2):170-2. doi: 10.1007/BF00168879.
In order to shorten the delay between the administration of tumour-imaging agents and obtainment of scintigrams, rapid delivery of radionuclide to tumours followed by rapid clearance from the blood is required. We used liposomes with biotin bound on their surface (B-liposomes) as carriers for rapid delivery. For rapid blood clearance, we employed avidin in the expectation that the strong affinity between biotin and avidin would result in the aggregation of B-liposomes in the blood circulation, and that these aggregates would be taken up rapidly by the reticuloendothelial system, resulting in the rapid elimination of liposomes and the radionuclide encapsulated in them. When B-liposomes encapsulating gallium-67 deferoxamine were intravenously administered to mice bearing sarcoma 180, large amounts of 67Ga were delivered to tumours by 4 h after injection, though the 67Ga blood level remained high. On the other hand, administration of avidin 4 h after administration of the B-liposomes dramatically reduced the blood level so that it was only 5% of that in the non-treated group 1 h later. As a result, the tumour-to-blood ratio reached nearly 14 at 5 h after radionuclide administration, suggesting that rapid tumour-imaging will be feasible by means of this method.
为了缩短肿瘤显像剂给药与获得闪烁图之间的延迟，需要将放射性核素快速输送到肿瘤，随后从血液中快速清除。我们使用表面结合有生物素的脂质体（B-脂质体）作为快速输送的载体。为了实现血液的快速清除，我们使用抗生物素蛋白，期望生物素与抗生物素蛋白之间的强亲和力会导致B-脂质体在血液循环中聚集，并且这些聚集体会被网状内皮系统迅速摄取，从而导致脂质体及其包裹的放射性核素被快速清除。当将包裹镓-67去铁胺的B-脂质体静脉注射给患有肉瘤180的小鼠时，注射后4小时大量的67Ga被输送到肿瘤，尽管67Ga的血液水平仍然很高。另一方面，在给予B-脂质体4小时后给予抗生物素蛋白可显著降低血液水平，以至于1小时后仅为未治疗组的5%。结果，放射性核素给药后5小时肿瘤与血液的比值达到近14，表明通过这种方法进行快速肿瘤显像将是可行的。
