Campbell Matthew, Kiang Anna-Sophia, Kenna Paul F, Kerskens Christian, Blau Christoph, O'Dwyer Laurence, Tivnan Amanda, Kelly Julie Anne, Brankin Brenda, Farrar Gwyneth-Jane, Humphries Peter
Ocular Genetics Unit, Department of Genetics, Trinity College Dublin, Dublin 2, Ireland.
J Gene Med. 2008 Aug;10(8):930-47. doi: 10.1002/jgm.1211.
The blood-brain barrier (BBB) contains tight junctions (TJs) which reduce the space between adjacent endothelial cells lining the fine capillaries of the microvasculature of the brain to form a selective and regulatable barrier.
Using a hydrodynamic approach, we delivered siRNA targeting the TJ protein claudin-5 to the endothelial cells of the BBB in mice.
We have shown a significant decrease in claudin-5 mRNA levels 24 and 48 hours post-delivery of siRNA, with levels of protein expression decreasing up to 48 hours post-injection compared to uninjected, phosphate-buffered saline (PBS)-injected and non-targeting siRNA-injected mice. We observed increased permeability at the BBB to molecules up to 742 Da, but not 4400 Da, using tracer molecule perfusion and MRI analysis. To illustrate the functional efficacy of size-selective and transient barrier opening, we have shown that enhanced delivery of the small neuropeptide thyrotropin-releasing hormone (TRH) (MW 360 Da) to the brains of mice 48 hours post-injection of siRNA targeting claudin-5 significantly modifies behavioural output.
These data demonstrate that it is now possible to transiently and size-selectively open the BBB in mice, allowing in principle the delivery of a wide range of agents for the establishment and treatment of experimental mouse models of neurodegenerative, neuropsychiatric and malignant diseases.
血脑屏障（BBB）包含紧密连接（TJs），紧密连接可减少脑微血管系统中细小毛细血管内衬的相邻内皮细胞之间的间隙，从而形成一个选择性且可调节的屏障。
我们采用流体动力学方法，将靶向紧密连接蛋白claudin-5的小干扰RNA（siRNA）递送至小鼠血脑屏障的内皮细胞。
我们发现，在递送siRNA后24小时和48小时，claudin-5 mRNA水平显著降低，与未注射、注射磷酸盐缓冲盐水（PBS）和非靶向siRNA的小鼠相比，注射后48小时内蛋白表达水平持续下降。通过示踪分子灌注和磁共振成像（MRI）分析，我们观察到血脑屏障对分子量高达742 Da的分子通透性增加，但对4400 Da的分子通透性未增加。为了说明大小选择性和短暂性屏障开放的功能效果，我们发现，在注射靶向claudin-5的siRNA后48小时，向小鼠脑内增强递送小分子神经肽促甲状腺激素释放激素（TRH）（分子量360 Da）可显著改变行为输出。
这些数据表明，现在有可能在小鼠中短暂且大小选择性地开放血脑屏障，原则上允许递送多种药物，用于建立和治疗神经退行性、神经精神性和恶性疾病的实验小鼠模型。
