In vivo detection of involvement of endogenous BM progenitor cells in glioma

描述(申请人提供)：由于胶质母细胞瘤(GBM)的多血管本质和相关的活跃的血管生成，研究人员增加了抗血管生成治疗作为使血管正常化和控制异常血管生成的辅助手段。抗血管生成治疗扰乱肿瘤血管，导致明显的缺氧。在GBM中，缺氧导致缺氧诱导因子1-α(HIF-1)表达上调。HIF-1上调SDF-1，而SDF-1又可能招募各种促血管生成的骨髓来源细胞。任何吸引更多内皮祖细胞的疗法都可能促进新生血管和促生长，这是抗血管生成疗法的一个矛盾效果。因此，我们假设使用VEGFR抑制剂的抗血管生成治疗将启动促血管生成因子的释放，导致内皮祖细胞(EPC)或骨髓祖细胞(BMPC)(不同类型的干细胞)的迁移和聚集，并增强难治性肿瘤的血管生成。本研究的目的是通过建立嵌合的小鼠模型，应用新的无创、先进的MRI和光学成像方法来监测肿瘤的进展和相关的外源性和内源性内皮祖细胞的迁移，以阐明难治性脑胶质瘤的新生血管形成机制。我们将分三个阶段进行研究：(1)建立嵌合小鼠模型，在人泛素C启动子的控制下，用转基因小鼠(C57BL/6-TG(UBC-GFP)30Scha/J)的骨髓细胞替代亚致死剂量照射的无菌小鼠的骨髓。这些嵌合小鼠将被用来产生原位人脑胶质瘤。(2)我们将通过MRI检测单独或联合应用vetanalib或AMD3100(或新的有效的CXCR4抑制剂)治疗后肿瘤血管通透性、增强模式、分布体积和扩散参数的变化，以及不同血管生成因子及其相关受体在肿瘤和周围组织中的变化；(3)我们将通过光学成像和细胞MRI分别确定在单独或联合使用vetanalib或AMD3100(或新的有效的CXCR4抑制剂)抗血管生成治疗期间内源性BMPC和外源性EPC的参与，这些结果将与血管生成因子和受体的表达相关联。内源性BMPC和外源性EPC在肿瘤新生血管形成中的作用也将被比较和关联。预计干细胞在抗血管生成治疗中有很强的作用。在不同的治疗方案下，内源性或给药干细胞积聚的差异将证明我们的假设，即干细胞在抗血管生成治疗中具有作用。相互关系的关系 当考虑抗血管生成治疗时，累积应用干细胞的MRI表现和不同的血管生成受体的表达将有助于临床医生修改治疗策略。 公共卫生相关性：拟议的研究将阐明抗血管生成/抗血管生成治疗后肿瘤新生血管的机制，并应用光学和磁共振成像技术跟踪肿瘤的变化。具体地说：1)我们将用GFP+骨髓替代骨髓细胞来建立嵌合动物模型；2)我们将使用现有的成像方式和技术在体内确定抗血管生成/抗血管生成治疗过程中肿瘤的变化；3)通过光学成像，我们将跟踪内源性GFP+骨髓前体细胞向肿瘤部位的迁移；4)我们将使用外源干细胞通过MRI确定干细胞在抗血管生成/抗血管生成治疗中的作用。5)我们将同时使用光学成像和细胞MRI来跟踪祖细胞在抗血管生成/抗血管生成治疗中如何参与肿瘤血管生成/血管生成。

DESCRIPTION (provided by applicant): Because of hypervascular nature of glioblastoma (GBM) and associated active angiogenesis, investigators have added anti-angiogenic treatment as an adjuvant to normalize blood vessels and control abnormal angiogenesis. Antiangiogenic therapy disturbs tumor vasculature, leading to marked hypoxia. In GBM, hypoxia leads to up-regulation of hypoxia inducible factor 1-alpha (HIF-1). HIF-1 up-regulates SDF-1, which in turn may recruit various pro-angiogenic bone marrow-derived cells. Any therapy that invites more EPCs might promote neovascularization and pro growth, a paradoxical effect of anti-angiogenic therapy. Therefore, we hypothesize that anti-angiogenic treatment using VEGFR inhibitors would initiate the release of pro-angiogenic factors, causing migration and accumulation of endothelial progenitor cells (EPCs) or bone marrow progenitor cells (BMPCs) (different types of stem cells), and enhanced angiogenesis in refractory tumors. The goal of this study is to elucidate neovascularization mechanisms in refractory glioma by making chimeric mouse model and applying novel non-invasive, state of the art MRI and optical imaging approach to monitor tumor progression and associated exogenous and endogenous EPCs' migration. We will conduct the research in three phases: (1) we will establish chimeric mouse model where bone marrow of sub-lethally irradiated athymic mouse will be replaced by bone marrow cells collected from bone marrow of transgenic mouse (C57BL/6-Tg(UBC-GFP)30Scha/J) that express GFP protein under the control of human ubiquitin C promoter. These chimeric mice will be used to generate orthotopic human glioma. (2) we'll determine the changes in tumor vascular permeability, enhancement patterns, distribution volume, and diffusion parameters by MRI, and changes in different angiogenic factors and their associated receptors in the tumor and surrounding tissues following the treatment with vetanalib or AMD3100 (or a newer potent CXCR4 inhibitor), separately or in combination; (3) we'll determine the involvement of endogenous BMPCs and exogenous EPCs by optical imaging and cellular MRI, respectively, during antiangiogenic treatments with vetanalib or AMD3100 (or a newer potent CXCR4 inhibitor), separately or in combination, and the findings will be correlated with the expression o angiogenic factors and receptors. Involvement of endogenous BMPCs and exogenous EPCs in tumor neovascularization will also be compared and correlated. It is anticipated that there is a strong role of stem cells during anti-angiogenic therapy. Differences in accumulation of the endogenous or administered stem cells following different treatment schedule will prove our hypothesis that there is a role for stem cells during anti-angiogenic treatment. Correlation of the accumulated administered stem cells with MRI findings and the expression of different angiogenic receptors will help clinicians to modify treatment strategy when anti-angiogenic therapy is considered. PUBLIC HEALTH RELEVANCE: The proposed investigations will shed new lights on the mechanisms of tumor neovascularization following anti-angiogenic/anti-vasculogenic treatments and apply both optical and MR imaging techniques to track changes in the tumor. Specifically: 1) we'll create a chimeric animal model by replacing bone marrow cells with GFP+ bone marrow, 2) we will use established imaging modalities and techniques to determine, in vivo, the changes in the tumors during anti-angiogenic/anti-vasculogenic treatments, 3) by optical imaging we'll track the migration of endogenous GFP+ bone marrow progenitor cells to the sites of tumor, 4) we will use exogenous stem cells to determine the role of stem cells during anti-angiogenic/anti-vasculogenic treatments by MRI, 5) we will use both optical imaging and cellular MRI to track how progenitor cells become involved in tumor angiogenesis/vasculogenesis during anti-angiogenic/anti-vasculogenic treatments.