HIV-1反式转录激活因子介导的脂质体在脊髓损伤大鼠体内分布的靶向性

Distribution targeting of HIV-1 trans-activator transcription mediated liposomes following spinal cordinjury in rats

目的：探讨HIV-1反式转录激活因子（trans-activator transcription,TAT）介导的脂质体作为药物载体在脊髓损伤大鼠体内分布的靶向性。方法：构建HIV-1 TAT介导的纳米脂质体,外接异硫氰酸荧光素（fluorescein isothiocyanate,FITC）作为标记。取8周龄雌性Wistar大鼠60只,随机分为2组,每组30只,每组分为未损伤、伤后24h及伤后1周3个时间点,每个时间点各10只。每组20只采用Impactor ModelⅡ打击建立T10脊髓损伤模型。Ⅰ组每个时间点尾静脉注射外接TAT的脂质体（9μg/ml,500μl）,Ⅱ组尾静脉注射不接TAT的脂质体（9μg/ml,500μl）。注射后1h取出T7~L1节段脊髓组织,冰冻组织切片暗视野下观察脂质体在脊髓组织中的分布情况。结果：Ⅰ组未损伤、伤后24h及伤后1周均在脊髓内部观察到FITC标记的脂质体,但未损伤脊髓中脂质体未进入神经元,伤后24h及伤后1周脂质体在损伤中心神经元中聚集,伤后24h距离损伤中心近端1.5cm处和远端1.5cm处神经元中脂质体的FITC荧光平均光密度（AOD）明显小于损伤中心（P〈0.05）。Ⅱ组在未损伤脊髓及伤后1周脊髓损伤中心区未观察到脂质体,伤后24h在脊髓损伤中心区观察到脂质体在神经元中聚集。两组伤后24h脊髓损伤中心AOD比较无统计学差异（P〉0.05）。结论：外接TAT的脂质体可以穿过大鼠正常的血脊髓屏障进入脊髓内部,并且具有进入受损脊髓组织神经元的靶向特异性。

Objective：To investigate the in vivo distribution targeting of HIV-1 trans-activator transcription （TAT） -mediated liposomes as drug carriers in rats.Method：HIV -1 TAT -mediated nanoliposome connected with fluorescein isothiocyanate （FITC） acting as a marker were constructed.60 female Wistar rats （8 week） were randomly divided into 2 groups with 30 animals in each group,3 subgroups（n=10） of each group were determined as no damage,24h and 1 week after injury.T10 spinal cord injury models were established by Impactor Model Ⅱ.Group Ⅰ were administed with tail-vein injection of external TAT liposomes （9μg/ml, 500μl） at each time point;group Ⅱ with tail-vein injection of liposomes alone （9μg/ml,500μl）.1h after injection,the T7 -L1 spinal cord specimen were harvested and observed under dark field microscopy for liposome distribution in spinal cord.Result：FITC-liposomes were observed in the spinal cord in group Ⅰ at 3 time points,but liposomes in intact spinal cord did not enter the neuron.At the time points of 24h and 1 week after injury,liposomes aggregation were noted in injury center inside neurons.24h after injury,FITC fluorescence average optical density （AOD） in neurons liposomes 1.5cm proximal and distal to injury centers were significantly less than in injury center （P0.05）.While in group Ⅱ,liposomes were not observed in the center of spinal cord injury at preinjury and 1 week after injury,and liposome aggregation were observed in neurons in the center of injury site 24h after injury.AOD at center of injury site 24h after injury showed no significant difference between two groups （P0.05）.Conclusion：The external TAT liposomes can cross the normal blood and spinal cord barrier,which shows damaged neurons targeting characteristics.