Multifuctional Nanovector For Diagnosis And Treatment Of Pediatric Brain Cancer

描述(申请人提供)：我们的长期目标是开发和验证新的纳米探针，作为成像标记和药物载体，用于脑癌的非侵入性诊断、分期和治疗。脑肿瘤治疗目前受到严重限制，因为无法非侵入性地准确诊断和分期疾病，选择性地靶向肿瘤细胞，并迅速监测受影响个体的治疗反应。像所有的脑癌一样，髓母细胞瘤很难治疗，因为它有神经毒性，肿瘤对外来物质有抵抗力，而且通过血脑屏障的潜在治疗手段很少。在这项研究中，我们建议开发一种集成的多功能纳米矢量器来诊断和治疗髓母细胞瘤，髓母细胞瘤是儿童最常见的脑癌形式。该纳米载体由一个超顺磁性氧化铁核心和一个可生物降解的聚合物外壳组成，包裹或连接着靶向配体(氯毒素)、基因治疗剂和近红外荧光团。氯毒素对神经外胚层来源的原发肿瘤表现出很强的亲和力，但不是正常脑细胞。我们还发现，骨形态发生蛋白-2(BMP-2)以自分泌和旁分泌的方式诱导髓母细胞瘤细胞死亡，但不会导致非肿瘤细胞的凋亡。该纳米载体可通过核磁共振成像和近红外荧光(NIRF)光学成像进行检测，以实现术前和术中肿瘤边缘的可视化。纳米载体的设计具有显著的分散性和生物稳定性，延长了血液循环时间，并具有独特的安全加载和有效输送药物的能力。该纳米载体针对髓母细胞瘤具有很高的特异性，可被靶细胞吞噬，并可在细胞内停留较长时间，这对于术中成像和体内药物反应的后期监测特别有利。拟开展的研究旨在(1)设计、合成、表征可靶向固定的纳米载体核壳结构，并验证其光学和磁共振对比度；(2)应用优化的肿瘤靶向MRI/NIRF纳米结合物携带编码骨形态发生蛋白-2的治疗性DNA，研究其在基因转染和体外诱导细胞凋亡中的作用；(3)验证和定量研究纳米载体细胞的靶向、转染、细胞凋亡、毒性、体内生物分布等特性。我们预计，基于这种可注射和可生物降解的新型纳米载体的技术将极大地提高髓母细胞瘤的诊断、预后和治疗终点的评估，并为消除儿童脑癌的痛苦和死亡提供令人振奋的新机会。

DESCRIPTION (provided by applicant): Our long-term objective is to develop and validate new nanoprobes serving both as imaging markers and drug carriers for non-invasive diagnosis, staging, and treatment of brain cancers. Brain tumor therapy is currently severely limited by an inability to noninvasively and precisely diagnose and stage disease, selectively target tumor cells, and prompt monitoring of the response to treatment in affected individuals. Like all cancers in brain, medulloblastoma are difficult to treat because of neurotoxicity, tumor resistance to foreign substances, and minimal delivery of potential therapies across the blood-brain barrier. In this research, we propose to develop an integrated multifunctional nanovector for diagnosis and treatment of medulloblastoma, the most common form of pediatric brain cancer. The nanovector consists of a superparamagnetic iron oxide core and a biodegradable polymer shell, encapsulated or conjugated with targeting ligands (chlorotoxin), gene therapeutic agents, and near infrared fluorophore. Chlorotoxin has shown a strong affinity for primary tumors of neuroectodermal origin but not normal brain cells. We have also identified that bone morphogenic protein-2 (BMP-2) induces medulloblastoma cell death in an autocrine and paracrine fashion but does not cause apoptosis in non-neoplastic cells. The nanovector is detectable by both MRI and near infrared fluorescence (NIRF) optical imaging to enable preoperative and intraoperative visualization of tumor margins. The nanovector is designed to have remarkable dispersity and biostability, prolonged circulation time in blood, and unique ability to safely load and effectively deliver drugs. The nanovector will target medulloblastoma with high specificity, be endocytosed by target cells, and retain inside the cells over extended periods of time, which is particularly advantageous for intraoperative imaging and post monitoring of drug response in vivo. Specific aims of the proposed research are to (1) design, synthesize, characterize the nanovector core-shell structure immobilized with targeting agents, and validate its optical and MR contrast capability; (2) apply the optimal tumor targeted MRI/NIRF nanoconjugate to deliver therapeutic DNA encoding BMP-2 and study its efficacy in gene transfection and inducing apoptosis in vitro; (3) validate and quantify nanovector cell targeting, transfection, apoptosis, toxicity, biodistribution in vivo in mouse flank and intracranial models of medulloblastoma. We anticipate that the technology based on this new injectable and biodegradable nanovector will dramatically advance the diagnosis, prognosis, and evaluation of therapeutic endpoints for medulloblastoma and offer exciting new opportunity for eliminating the suffering and death of children with brain cancer.