Multifuctional Nanovector For Diagnosis And Treatment Of Pediatric Brain Cancer

描述（由申请人提供）：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，用于非侵入性脑癌的诊断、分期和治疗。脑肿瘤治疗目前受到严重限制，无法无创准确诊断和分期疾病，选择性靶向肿瘤细胞，以及及时监测受影响个体对治疗的反应。像所有脑癌一样，髓母细胞瘤很难治疗，因为它具有神经毒性，肿瘤对外来物质有抵抗力，而且潜在的治疗方法通过血脑屏障的可能性很小。在这项研究中，我们建议开发一种集成的多功能纳米载体，用于诊断和治疗髓母细胞瘤，这是儿童脑癌中最常见的形式。该纳米载体由超顺磁性氧化铁内核和可生物降解的聚合物外壳组成，并与靶向配体（氯毒素）、基因治疗剂和近红外荧光团包被或偶联。氯毒素对神经外胚层原发肿瘤有很强的亲和力，但对正常脑细胞没有亲和力。我们还发现骨形态发生蛋白-2 （BMP-2）以自分泌和旁分泌方式诱导髓母细胞瘤细胞死亡，但不引起非肿瘤细胞凋亡。该纳米载体可通过MRI和近红外荧光（NIRF）光学成像检测到，从而实现术前和术中肿瘤边缘的可视化。该纳米载体具有显著的分散性和生物稳定性，延长血液循环时间，以及安全有效地装载和输送药物的独特能力。纳米载体将以高特异性靶向成神经管细胞瘤，被靶细胞内吞，并在细胞内保留较长时间，这对于术中成像和体内药物反应后监测特别有利。本研究的具体目标是：(1)设计、合成、表征靶向剂固定化的纳米载体核壳结构，并验证其光学和磁共振对比能力；(2)应用最佳肿瘤靶向MRI/NIRF纳米偶联物传递编码BMP-2的治疗性DNA，并在体外研究其基因转染和诱导细胞凋亡的效果；(3)验证并量化纳米载体细胞在成神经管细胞瘤小鼠侧腹和颅内模型中的靶向、转染、凋亡、毒性和生物分布。我们预计，基于这种新的可注射和可生物降解纳米载体的技术将极大地促进成神经管细胞瘤的诊断、预后和治疗终点的评估，并为消除脑癌儿童的痛苦和死亡提供令人兴奋的新机会。

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.