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，作为成像标记物和药物载体，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，无法无创和精确地诊断和分期疾病，选择性靶向肿瘤细胞，并迅速监测受影响个体对治疗的反应。与所有脑部癌症一样，髓母细胞瘤难以治疗，因为神经毒性，肿瘤对外来物质的抵抗力以及穿过血脑屏障的潜在治疗的最小递送。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，这是最常见的儿科脑癌。纳米载体由超顺磁性氧化铁核和生物可降解聚合物壳组成，封装或缀合有靶向配体（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性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，但不会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，以实现术前和术中肿瘤边缘的可视化。纳米载体被设计为具有显著的分散性和生物稳定性，延长血液循环时间，以及安全装载和有效递送药物的独特能力。纳米载体将以高特异性靶向髓母细胞瘤，被靶细胞内吞，并在延长的时间段内保留在细胞内，这对于体内药物反应的术中成像和后监测特别有利。本研究的具体目标是：（1）设计、合成、表征固定有靶向药物的纳米载体核壳结构，并验证其光学和磁共振成像对比能力;（2）将最佳的肿瘤靶向MRI/NIRF纳米偶联物用于递送编码BMP-2的治疗性DNA，并研究其体外基因转染和诱导凋亡的功效;（3）在髓母细胞瘤的小鼠侧腹和颅内模型中验证和定量纳米载体细胞靶向、转染、凋亡、毒性、体内生物分布。我们预计，基于这种新的可注射和可生物降解的纳米载体的技术将大大推进髓母细胞瘤的诊断，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.