TAT-PEG-磁性纳米脂质体跨脊髓损伤大鼠血脊髓屏障的观察

摘要

Objective To evaluate the ability of a kind of novel magnetic liposomes modified with polyethylene glycol(PEG) and transactivating-transduction protein (TAT) to cross the blood spinal cord barrier (BSCB) so as to demonstrate whether or not they can accumulate at the lesions of injured spinal cord. Methods The novel liposomes were made through reverse-phase evaporation method modified with polyethylene glycol (PEG) and transactivating-transduction protein (TAT) with an iron core. Thirty-six Wistar rats subject to spinal cord injury (SCI) at T10 were randomly divided into three groups (Groups Ⅰ ,Ⅱ and Ⅲ ). The rats of Group Ⅲ were injected with TAT-PEG loaded magnetic liposomes (4.55 mg/kg).The rats of Group Ⅱ received an injection of the equivalent PEG loaded magnetic liposomes while those of control group ( Group Ⅰ ) the equivalent normal saline. The accumulation of liposomes was observed by MRI (magnetic resonance imaging), Prussian blue staining, electron microscope and flame atomic absorption spectrophotometer. Results This kind of TAT-PEG loaded magnetic liposomes could croas the BSCB and enter into the cells around the injured tissue. A low signal of T2WI on MRI could also be found in Group Ⅲ.The results of flame atomic absorption spectrophotometer showed that the iron content accumulated around the lesion site in Group Ⅲ was obviously higher than the other two groups (P＜0.05). Conclusion The TATPEG loaded magnetic liposomes may be employed as one kind of novel drug carrier to cross the BSCB and accumulate at tissue cells of spinal cord. It is likely to become a new therapy for SCL%目的 探讨TAT-PEG-磁性纳米脂质体作为一种药物载体通过尾静脉注入跨越大鼠血脊髓屏障(BSCB)并在脊髓损伤局部聚集的情况.方法 通过反向蒸发法制备新型磁性纳米脂质体,通过表面功能基团连接TAT、PEG而形成TAT-PEG-磁性纳米脂质体,使其兼备跨膜功能、长循环功能及核磁活体示踪功能;36只成年Wistar大鼠以Impactor Model-Ⅱ法建立T10急性脊髓损伤模型,随机分为3组,Ⅰ组:对照组,Ⅱ组:PEG-多功能脂质体组,Ⅲ组:TAT-PEG-多功能脂质体组,各组均12只.将制备出的TAT-PEG-多功能脂质体,通过尾静脉注入Ⅲ组大鼠脊髓损伤模型体内,将PEG-多功能脂质体按同样剂量尾静脉注入Ⅱ组大鼠体内,Ⅰ组尾静脉注入等量生理盐水,通过核磁共振(MRI)动态观察TAT-PEG-多功能脂质体在脊髓损伤局部的靶向聚集与扩散情况、通过普鲁士蓝染色、电镜观察、火焰原子吸收分光光度法检测,分析其在脊髓损伤局部的聚集情况.结果 TAT-PEG-磁性纳米脂质体可以穿过BSCB聚集在脊髓损伤局部,MRI动态观察显示,这种药物载体逐渐在损伤局部浓集,主要呈现T2WI低信号.普鲁士蓝染色观察到聚集在损伤局部组织的蓝染铁颗粒,电镜进一步观察到脊髓组织神经细胞内聚集的铁颗粒,火焰原子吸收分光光度法分析显示Ⅲ组脊髓损伤局部铁元素含量相对升高,差异有统计学意义(P＜0.05).结论 TAT-PEG-磁性纳米脂质体作为一种新型药物载体,通过静脉途径注入体内,可以跨越BSCB聚集在脊髓损伤局部,并能将其包裹的物质释放入损伤局部的神经细胞内,可作为脊髓损伤的治疗的新思路.