肿瘤相关巨噬细胞介导的脑胶质瘤术中实时多模态成像与光动力治疗

Malignant cerebral gliomas has a high mortality and recurrence rate. The degree of operative removal directly affects the prognosis of patients with the glioma. There are large numbers of tumor associated macrophages in the glioma lesion with different pathologic grades, which locates around the necrosis area of tumor and the peripheral region between tumor and normal tissue.According to our previous study, optical/MRI contrast agent labeled monocytes can migrate to the hepatocarcinoma lesion and peripheral area in rats after injection by tail vein. In this study, an upconversion luminescence(UCL)/MRI and photodynamic therapy based multifunctional nano particle should be used to label the peripheral blood monocytes. After the labeled monocytes are injected into the body of rats with cerebral glioma by the tail vein, the intraopertive UCL/MRI should be used to monitor the distribution of labelded cells in the tumor area and guide the surgical excision of the tumor lesion. The ablation of tumor rim will be maken by intraoperative photodynamic therapy. This study is to explore the feasibility of TAMS mediated intraoperative UCL/MRI in determining the tumor border and directing the operative removal of glioma lesions, as well as photodynamic therapy in the depletion of survival tumor cells in the peripheral area of tumors.TAMS mediated intraoperative UCL/MRI and photodynamic therapy has several advantages, such as favorable biocompatibility, high sensitivity imaging and without the limitation of blood brain barrier, which can provide precise operation navigation and complete ablation of tumor rim. This study may open a new approach to intraoperative imaging and therapy in galiomas.

恶性脑胶质瘤术后易复发，死亡率高，手术切除程度直接影响患者的预后。不同级别的脑胶质瘤内均含有大量的肿瘤相关巨噬细胞（TAMS），主要分布于肿瘤坏死区周边及其与正常组织交界区。本课题组前期研究表明，光学/MRI对比剂标记单核细胞并经尾静脉注入体内后，能定向迁移至大鼠肝癌病灶内及周边区。 本研究拟构建基于上转换光学（UCL）/MRI与光动力治疗的多功能纳米颗粒，体外标记外周血单核细胞，经尾静脉注入脑胶质瘤模型鼠体内，采用术中UCL/MRI观察标记细胞在肿瘤区分布、指导手术切除病灶，术中光动力治疗行瘤缘消融，探讨TAMS介导的胶质瘤术中UCL/MRI确定肿瘤边界、指导肿瘤完整切除及光动力治疗清除瘤缘残存肿瘤细胞的可行性。TAMS介导的术中UCL/MRI与光动力治疗，具有生物相容性好、成像敏感性高、不受血脑屏障限制等特点，实现精准手术导航与彻底瘤缘消融，为脑胶质瘤术中成像及治疗提供了一种新的思路。

胶质瘤呈浸润性生长，手术难以完整切除，术后易复发。由于血脑屏障的存在，很多造影剂和药物难以到达胶质瘤内，胶质瘤的精准成像和有效治疗仍面临挑战。临床迫切需要开发一种能实现胶质瘤精准术前、术中边界成像并控制术后复发的诊疗一体化技术。本研究采用巨噬细胞装载具有光学/MRI/光声成像及光热治疗效果的MFe3O4-Cy5.5纳米探针，探讨其跨越血脑屏障并向深部胶质瘤区域定向聚集能力，实现术前、术中多模态成像及采用光热治疗抑制术后残留灶的效果。研究结果表明，Fe3O4-Cy5.5纳米探针具有良好的顺磁性效应、光热转换效果、稳定的荧光成像与光声成像效果，生物相容性好，易被巨噬细胞大量吞噬，且不影响细胞活力及迁移能力，最佳标记浓度与标记时间分别是25ug/ml及24小时。体内实验表明，尾静脉注射负载Fe3O4-Cy5.5的巨噬细胞后，其能跨越血脑屏障逐步向大鼠脑内胶质瘤周边聚集，同时实现胶质瘤术前及术中光学/光声/MRI多模态成像，成像时间窗长达6天。活体光热治疗实验表明，在部分切除的大鼠原位胶质瘤模型中，尾静脉注射MFe3O4-Cy5.5纳米探针后，能有效地聚集到胶质瘤残留灶并被光声成像检测到，局部光热治疗能有效诱导残存肿瘤细胞凋亡，抑制肿瘤术后复发。本研究结果表明巨噬细胞介导的诊疗一体化探针为胶质瘤术前及术中多模态边界成像与有效的光热治疗提供了一种有前景的技术平台。