Unger E, Needleman P, Cullis P, Tilcock C
Department of Radiology, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Invest Radiol. 1988 Dec;23(12):928-32. doi: 10.1097/00004424-198812000-00010.
To evaluate the use of liposomes containing Gadolinium-DTPA (Gd-DTPA) as potential intravascular contrast agents, we synthesized and tested Gd-DTPA liposomes. A freeze-thaw extrusion process was used to synthesize neutral unilamellar vesicles. Using this technique, we prepared 0.4 micron vesicles with encapsulation efficiency as high as 39% for Gd-DTPA. In vitro dialysis showed that essentially 100% of the Gd-DTPA was retained with the liposomes after 72 hours of dialysis. MR imaging of in vitro samples showed concentration-dependent increase in signal intensity with Gd-DTPA liposomes. Imaging of rats after intravenous injection of Gd-DTPA liposomes showed sustained intravascular contrast enhancement of vascular structures and liver greater than free Gd-DTPA. There was no evidence of acute toxicity in rats during the imaging experiments or on follow-up of two months. Paramagnetic liposomes may be useful to enhance the vasculature, liver, and spleen.
为评估含钆-二乙三胺五乙酸（Gd-DTPA）的脂质体作为潜在血管内造影剂的用途，我们合成并测试了Gd-DTPA脂质体。采用冻融挤压法合成中性单层囊泡。利用该技术，我们制备了粒径为0.4微米的囊泡，Gd-DTPA的包封率高达39%。体外透析显示，透析72小时后，基本上100%的Gd-DTPA保留在脂质体中。体外样品的磁共振成像显示，Gd-DTPA脂质体的信号强度呈浓度依赖性增加。静脉注射Gd-DTPA脂质体后对大鼠进行成像，结果显示血管结构和肝脏的血管内造影增强持续时间长于游离Gd-DTPA。在成像实验期间及随后两个月的随访中，未发现大鼠有急性毒性迹象。顺磁性脂质体可能有助于增强血管、肝脏和脾脏的显影。
