Application of Carbon Nanotubes for Macrophage Activation in Brain Tumor Models

描述（申请人提供）：恶性胶质瘤是最致命的癌症之一。小胶质细胞（MG）和巨噬细胞（MP）是大脑对恶性脑肿瘤反应的重要组成部分。虽然这些细胞对肿瘤微环境的确切贡献尚不清楚，但我们的初步研究表明，脑肿瘤模型中的MG/MP免疫功能受到肿瘤细胞的抑制。这种抑制很可能是通过MG/MP中Stat3的激活发生的。我们假设抑制MG/MP中的Stat3可以增强它们的促炎功能，并可能导致肿瘤消失。在体内修饰MG/MP功能是困难的，因为这些细胞对标准病毒和非病毒基因转移方法的转染具有抗性。然而，MG/MP固有的吞噬特性可以用于纳米颗粒介导的药物递送到这些细胞中。由于与病毒系统相比，纳米颗粒系统的毒性较低，因此最近在治疗领域引起了极大的兴奋。碳纳米管（CNT）就是一个例子，它是一种独特的纳米结构，具有卓越的电子和机械性能。碳纳米管携带小抑制RNA （siRNA）进入MP的能力可用于脑肿瘤模型中MG/MP的调节和刺激。为了开发一种基于MG/MP激活的新型脑肿瘤免疫疗法，我们建议在胶质瘤模型中研究碳纳米管将siRNA递送到MG/MP中的效果。在该项目的第一个目标中，我们将优化CNTs在体外将siRNA递送到MG中的功效。更具体地说，我们将评估以下参数：CNT毒性，CNT介导的siRNA传递和基因沉默，以及CNT通过Stat3抑制介导的MG激活。该项目的第二个目标是在脑肿瘤模型中研究碳纳米管将siRNA递送到MG/MP中的功效。在优化siRNA体外递送条件后，我们将表征cnt介导的siRNA递送后实验性脑肿瘤中CNS反应和基因沉默持续时间。最后，这些结果将用于测试cnt介导的Stat3-siRNA递送是否会在小鼠胶质瘤模型中激活MG/MP并增强抗肿瘤免疫。总的来说，这些研究将研究一种基于碳纳米管介导的siRNA递送的新型免疫治疗方法，该方法可用于脑肿瘤中MG/MP的激活，并最终转化为人类应用。公共卫生相关性：恶性胶质瘤是人类最致命的癌症之一，两年生存率不到20%。尽管免疫疗法正在被研究作为恶性脑肿瘤的一种可能的治疗方法，但免疫抑制胶质瘤环境限制了这种方法的疗效。我们相信，使用碳纳米管（CNT）递送系统直接激活先天免疫系统可能有助于克服这种局部免疫抑制，并最终导致恶性脑肿瘤治疗的新型免疫治疗方法的发展。此外，用碳纳米管修饰脑巨噬细胞可能与其他中枢神经系统疾病过程具有治疗相关性，如创伤和中风，其中脑巨噬细胞在其发病机制中起关键作用。

DESCRIPTION (provided by applicant): Malignant gliomas are among the most fatal cancers. Microglia (MG) and macrophages (MP) represent a significant component of the brain response to malignant brain tumors. Although the exact contribution of these cells to the tumor microenvironment is unclear, our preliminary studies indicate that MG/MP immune function in brain tumor models is suppressed by tumor cells. This suppression most likely occurs through the activation of Stat3 in MG/MP. We hypothesize that inhibition of Stat3 in MG/MP can enhance their pro-inflammatory function and could lead to tumor abrogation. In vivo modification of MG/MP function is difficult because these cells are resistant to transfection with standard viral and nonviral gene transfer methods. However, the inherent phagocytic property of MG/MP can be exploited for nanoparticle-mediated drug delivery into these cells. Due to their low toxicity in comparison to viral systems, nanoparticle systems have recently generated significant excitement in the field of therapeutics. One example is carbon nanotubes (CNT), which are unique nanostructures with remarkable electronic and mechanical properties. The ability of CNTs to carry small inhibitory RNA (siRNA) into MP could be exploited for MG/MP modulation and stimulation in brain tumor models. To develop a novel brain tumor immunotherapy based on MG/MP activation, we propose to study the efficacy of CNTs for siRNA delivery into MG/MP in glioma models. In the first Aim of the project, we will optimize the efficacy of CNTs for siRNA delivery into MG in vitro. More specifically, we will evaluate the following parameters: CNT toxicity, CNT-mediated siRNA delivery and gene silencing and CNT-mediated MG activation through Stat3 inhibition. The second Aim of the project will examine the efficacy of CNTs for siRNA delivery into MG/MP in brain tumor models. After optimizing siRNA delivery conditions in vitro, we will characterize CNS response and duration of gene silencing in experimental brain tumors following CNT-mediated siRNA delivery. Finally, these results will be used to test whether CNT-mediated Stat3-siRNA delivery results in MG/MP activation and enhancement of antitumor immunity in a murine glioma model. Overall, these studies will investigate a novel immunotherapy approach based on CNT-mediated siRNA delivery that can be used for MG/MP activation in brain tumors and ultimately be translated for human applications. PUBLIC HEALTH RELEVANCE: With a two-year survival of less than 20%, malignant gliomas are among the most fatal cancers in humans. Although immunotherapy is being studied as a possible treatment for malignant brain tumors, the immunosuppressive glioma environment has limited the efficacy of this approach. We believe that direct activation of the innate immune system using a carbon nanotube (CNT) delivery system may help overcome this local immunosuppression and ultimately lead to the development of a novel immunotherapeutic approach for the treatment of malignant brain tumors. Furthermore, modification of brain macrophages with CNT may have therapeutic relevance to other CNS disease processes, such as trauma and stroke, where brain macrophages play a key role in their pathogenesis.