Development of liposome for targeting therapy against brain tumor

目的脂质体包封是一种有效的给药方法。在脑内，关于脂质体的研究已经有很多报道，但脂质体本身通过血脑屏障渗透的实际机制尚未阐明。为了研究其作用机制，我们采用原代培养的牛脑微血管内皮细胞（BMEC）作为体外血脑屏障模型，研究了脂质体包裹顺铂（CDDP）对血脑屏障通透性的影响。方法按照audus和Borchardt的方法，在聚碳酸酯包被的胶原膜上分离培养dbmec。将带有聚碳酸酯膜的BMEC融合单层膜从培养皿中分离出来，并放置在并排扩散细胞的两半之间。每个腔内填充3ml转运实验缓冲液，保持在37 / 4 / 3的温度下。以鸡蛋-磷脂酰胆碱为原料，采用反相蒸发法制备包封CDDP的脂质体。供体腔用包封CDDP悬浮液或游离CDDP溶液的脂质体脉冲至终浓度20muM。受体腔每隔15、30分钟取样一次。用原子吸收分光光度计测定铂的浓度。结果与结论30 min时，CDDP脂质体在37ºC下的渗透系数为1.22*10^<-4> (cm/sec)，在4ºC下的渗透系数为0.21*10^<-4> (cm/sec)，差异有统计学意义。我们的研究结果表明，包裹在脂质体中的CDDP可以通过能量依赖的跨细胞运输方式通过血脑屏障进行运输。

PurposeLiposome encapsulation is an effective method for drug delivery system. In brain, many researches related to liposomes have been reported, but the actual mechanism by which liposome itself permeates through blood-brain barrier (BBB) has not been elucidated. To study the mechanisms, we investigated the BBB permeability of cisplatin (CDDP) encapsulated in liposome using primary culture of bovine brain microvessel endothelial cells (BMEC) as an in vitro BBB model.MethodBMECs were isolated and cultured on collagen coated polycarbonate membranes according to the protocol of audus and Borchardt. The BMEC confluent monolayrs with polycarbonate membranes were detached from the dishes, and placed in between the two halves of side-by-side diffusion cells. Each chamber was filled with 3ml of transport assay buffer, and kept at 37ﾟC of 4ﾟC.Liposomes encapsulating CDDP were prepared from egg-phosphatidylcholine by reverse-phase evaporation method. The donor chamber was pulsed with liposome encapsulating CDDP suspension or free CDDP solution to a final concentration of 20muM.The receptor chamber was sampled at 15-, 30-min intervals. The platinum concentration was measured by atomic absorption spectrophotometer.Result adn ConclusionAt 30-min, the permeability coefficient of liposomal CDDP at 37ﾟC was 1.22*10^<-4> (cm/sec), and that for 4ﾟC was 0.21*10^<-4> (cm/sec) which is statistically significant. Our findings suggest that CDDP encapsulated in liposome could transported through BBB by way of energy-dependent transcellular transport.