Molecular Immunology Unit, UCL Institute of Child Health, London WC1N 1EH, UK; Centre for Advanced Biomedical Imaging, Department of Medicine and Institute of Child Health, University College London, London WC1E 6DD, UK.
Biomaterials. 2013 Dec;34(36):9190-200. doi: 10.1016/j.biomaterials.2013.07.081. Epub 2013 Aug 12.
Convection enhanced delivery (CED) is a method of direct injection to the brain that can achieve widespread dispersal of therapeutics, including gene therapies, from a single dose. Non-viral, nanocomplexes are of interest as vectors for gene therapy in the brain, but it is essential that administration should achieve maximal dispersal to minimise the number of injections required. We hypothesised that anionic nanocomplexes administered by CED should disperse more widely in rat brains than cationics of similar size, which bind electrostatically to cell-surface anionic moieties such as proteoglycans, limiting their spread. Anionic, receptor-targeted nanocomplexes (RTN) containing a neurotensin-targeting peptide were prepared with plasmid DNA and compared with cationic RTNs for dispersal and transfection efficiency. Both RTNs were labelled with gadolinium for localisation in the brain by MRI and in brain sections by LA-ICP-MS, as well as with rhodamine fluorophore for detection by fluorescence microscopy. MRI distribution studies confirmed that the anionic RTNs dispersed more widely than cationic RTNs, particularly in the corpus callosum. Gene expression levels from anionic formulations were similar to those of cationic RTNs. Thus, anionic RTN formulations can achieve both widespread dispersal and effective gene expression in brains after administration of a single dose by CED.
脑内强制灌流（CED）是一种可将药物（包括基因治疗药物）直接注射至脑部的方法，单次给药即可实现药物的广泛分散。非病毒纳米复合物作为脑内基因治疗的载体引起了广泛关注，但给药后应实现最大分散度以尽量减少所需注射次数，这一点至关重要。我们假设CED 给药后带负电荷的纳米复合物应比带正电荷的纳米复合物（与细胞表面带负电荷的成分如蛋白聚糖静电结合，限制其扩散）具有更广泛的脑内分散度。我们制备了含有神经降压肽靶向肽的带负电荷的受体靶向纳米复合物（RTN），并与带正电荷的 RTN 进行了分散度和转染效率的比较。两种 RTN 均用钆进行标记，以便通过 MRI 定位脑内分布，通过 LA-ICP-MS 定位脑切片分布，并用罗丹明荧光团进行检测，以荧光显微镜观察。MRI 分布研究证实，带负电荷的 RTN 比带正电荷的 RTN 分散度更广，尤其是在胼胝体中。带负电荷的制剂的基因表达水平与带正电荷的 RTN 相似。因此，CED 单次给药后，带负电荷的 RTN 制剂既能实现广泛的分散度，又能有效实现脑内基因表达。
