Genetically-Modified Neural Stem Cell Based Virotherapy for Invasive Gliomas

描述(申请人提供)：多形性胶质母细胞瘤是中枢神经系统的一种原发恶性肿瘤，由于这些肿瘤的播散性，几乎所有人都是致命的。在此背景下，我们的实验室和其他实验室研究了神经干细胞(NSCs)独特的亲肿瘤特性，作为在大脑中靶向输送抗癌药物的新平台。然而，尽管神经干细胞表现出强烈的肿瘤趋向性，但只有一小部分移植细胞能够向肿瘤迁移。这种较差的肿瘤归巢效率是基于NSC的抗癌治疗方法的限制因素之一，必须加以解决。在此基础上，我现在建议研究神经干细胞固有的趋瘤特性的潜在分子机制，这将使我们能够制定方案，进一步提高神经干细胞的肿瘤归巢效率。我们的初步数据表明，基于VEGFR2和Nestin的表达水平，NSCs的迁移亚群与非迁移亚群存在显著差异。此外，阻断VEGFR2/VEGF信号显著削弱NSCs的趋瘤迁移特性。因此，进一步详细了解调节神经干细胞迁移特性的信号通路对于开发基于神经干细胞的优化靶向治疗(目标1)至关重要。此外，已报道的神经干细胞的免疫抑制特性是其作为细胞利用的一个非常吸引人的特性。 作为新型抗胶质瘤疗法的载体，它们将使溶瘤病毒等治疗有效载荷免受宿主免疫反应的影响。因此，我现在建议在病毒感染的背景下表征NSC介导的免疫抑制剂的分子性质，并研究它如何有助于提高抗胶质瘤溶瘤病毒疗法的疗效(目标2)。最后，我们的初步数据显示，由于复制介导的载体细胞裂解，NSCs的活性在体外与溶瘤病毒负载时显著受损。这对于治疗性病毒的肿瘤特异性扩增是必不可少的一步，但对于载体细胞的长期存活和肿瘤特异性归巢却是违反直觉的。基于此，我推测在体外负载过程中暂时阻断病毒复制将增强神经干细胞对胶质瘤的存活、负载能力和趋向性。在我们最终的具体目标中，我现在建议开发一种诱导系统，使我们能够在不改变神经干细胞的存活和趋向性的情况下，最大限度地增加体外溶瘤病毒的载量(目标3)。总之，拟议的研究有可能产生超越神经肿瘤学的影响，并将加速干细胞治疗在临床上的转化。 公共卫生相关性：多形性胶质母细胞瘤(GBM)仍然是人类最致命的癌症之一，中位生存期约为12至15个月。神经干细胞具有独特的固有特性，可以在整个大脑中迁移，并以侵袭性实体肿瘤为靶点，包括胶质瘤。这为选择性地将抗癌药物靶向输送到播散性肿瘤提供了一个新的平台。本提案中概述的研究旨在了解神经干细胞的肿瘤归巢特性的分子机制，并利用这些信息来提高基于NeuRA干细胞的治疗这种疾病的新策略的靶向效率。我们相信，这项拟议的研究计划有可能产生超越神经肿瘤学的影响，并将加速干细胞治疗在临床上的转化。

DESCRIPTION (provided by applicant): Glioblastoma multiforme is a primary malignancy of the central nervous system that is nearly universally fatal due to the disseminated nature of these tumors. In this context, our lab and others have investigated unique tumor-tropic properties of neural stem cells (NSCs) as a novel platform for targeted delivery of anti-cancer agents in the brain. However, despite the strong tumor tropism exhibited by NSCs, only a small portion of the transplanted cells is able to migrate towards the tumor. This poor tumor homing efficiency is one of the limiting factors for NSC-based anti-cancer therapeutic approach and must be address. On this basis, I now propose to study the underlying molecular mechanisms of the inherent tumor-tropic properties of NSCs, which will allow us to develop protocol to further improve the tumor homing efficiency of NSCs. Our preliminary data indicated that migratory subpopulation of NSCs differs significantly from their nonmigratory counterpart based on the level of VEGFR2 and nestin expression. Moreover, blocking VEGFR2/VEGF signaling significantly impaired tumor-tropic migratory properties of NSCs. Thus, further detail understanding of signaling pathways that regulate migratory properties of NSCs will be crucial for development of optimized NSC-based targeted therapy (Aim 1). In addition, the reported immunosuppressive properties of NSCs are a very attractive attribute to their utilization as a cell carrier for novel anti-glioma therapy given that they will allow therapeutic payloads such as oncolytic viruses to be shielded from the host immune response. Therefore, I now propose to characterize the molecular nature of NSC-mediated immunosuppressant in the context of viral infection and examine how it may help to enhance therapeutic efficacy of anti-glioma oncolytic virotherapy (Aim 2). And finally, our preliminary data show that the viability of NSCs is significantly compromised upon ex vivo loading with the oncolytic virus due to replication-mediated carrier cell lysis. This is an essential step for the tumor-specific amplification of the therapeutic viruses, but counter-intuitive for long-term survival and tumor-specific homing of the carrier cells. Based on this, I hypothesize that blocking viral replication transiently during ex vvo loading will enhance the survival, loading capacity and tropism of NSCs for gliomas. In our final specific aim, I now propose to develop an inducible system that will allow us to maximize the ex vivo loading of the oncolytic virus without altering the survival and tropism of the NSCs (Aim 3). In conclusion, the proposed studies have the potential to making an impact beyond neuro-oncology and will accelerate the translational of the stem cell-based therapy in the clinic. PUBLIC HEALTH RELEVANCE: Glioblastoma multiforme (GBM) remains one of the deadliest classes of human cancers with a median survival rate of approximately 12 to 15 months. Neural stem cells have the unique inherent property to migrate throughout the brain and target invasive solid tumors, including gliomas. This provides a novel platform for targeted delivery of anti-cancer agents to disseminated tumors selectively. The studies outlined in this proposal are geared towards understanding the molecular mechanisms of the tumor homing properties of neural stem cells and utilizing this information to enhance the targeting efficiency of novel neura stem cell-based therapeutic strategies for this disease. We believe that this proposed research plan has the potential to make an impact beyond neuro-oncology and will accelerate the translational of the stem cell-based therapy in the clinic.