Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
J Control Release. 2017 Sep 28;262:37-46. doi: 10.1016/j.jconrel.2017.07.009. Epub 2017 Jul 8.
The discovery of powerful genetic targets has spurred clinical development of gene therapy approaches to treat patients with malignant brain tumors. However, lack of success in the clinic has been attributed to the inability of conventional gene vectors to achieve gene transfer throughout highly disseminated primary brain tumors. Here, we demonstrate ex vivo that small nanocomplexes composed of DNA condensed by a blend of biodegradable polymer, poly(β-amino ester) (PBAE), with PBAE conjugated with 5kDa polyethylene glycol (PEG) molecules (PBAE-PEG) rapidly penetrate healthy brain parenchyma and orthotopic brain tumor tissues in rats. Rapid diffusion of these DNA-loaded nanocomplexes observed in fresh tissues ex vivo demonstrated that they avoided adhesive trapping in the brain owing to their dense PEG coating, which was critical to achieving widespread transgene expression throughout orthotopic rat brain tumors in vivo following administration by convection enhanced delivery. Transgene expression with the PBAE/PBAE-PEG blended nanocomplexes (DNA-loaded brain-penetrating nanocomplexes, or DNA-BPN) was uniform throughout the tumor core compared to nanocomplexes composed of DNA with PBAE only (DNA-loaded conventional nanocomplexes, or DNA-CN), and transgene expression reached beyond the tumor edge, where infiltrative cancer cells are found, only for the DNA-BPN formulation. Finally, DNA-BPN loaded with anti-cancer plasmid DNA provided significantly enhanced survival compared to the same plasmid DNA loaded in DNA-CN in two aggressive orthotopic brain tumor models in rats. These findings underscore the importance of achieving widespread delivery of therapeutic nucleic acids within brain tumors and provide a promising new delivery platform for localized gene therapy in the brain.
强大的基因靶点的发现促进了基因治疗方法的临床发展，以治疗恶性脑肿瘤患者。然而，临床治疗的失败归因于传统基因载体无法在高度弥散的原发性脑肿瘤中实现基因转移。在这里，我们证明了由 DNA 与可生物降解聚合物聚（β-氨基酯）（PBAE）的混合物凝聚而成的小纳米复合物，以及与 5kDa 聚乙二醇（PEG）分子缀合的 PBAE（PBAE-PEG），可以迅速穿透健康的大脑实质和大鼠的原位脑肿瘤组织。在新鲜组织中观察到这些负载 DNA 的纳米复合物的快速扩散表明，由于其密集的 PEG 涂层，它们避免了在大脑中的粘性捕获，这对于在通过对流增强递送后在体内实现广泛的转基因表达至关重要。与仅由 PBAE 组成的纳米复合物（负载 DNA 的常规纳米复合物，或 DNA-CN）相比，PBAE/PBAE-PEG 混合纳米复合物（负载 DNA 的穿透性纳米复合物，或 DNA-BPN）中的转基因表达在肿瘤核心中更为均匀，并且仅对于 DNA-BPN 制剂，转基因表达才会超出肿瘤边缘，在那里可以发现浸润性癌细胞。最后，负载抗癌质粒 DNA 的 DNA-BPN 与相同质粒 DNA 负载在 DNA-CN 中相比，在两种侵袭性大鼠原位脑肿瘤模型中提供了显著提高的存活率。这些发现强调了在脑肿瘤内实现治疗性核酸广泛传递的重要性，并为大脑内局部基因治疗提供了一个有前途的新传递平台。
