González-Gómez Pilar, Crecente-Campo Jose, Zahonero Cristina, de la Fuente Maria, Hernández-Laín Aurelio, Mira Helena, Sánchez-Gómez Pilar, Garcia-Fuentes Marcos
UFIEC, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Department of Pharmacy and Pharmaceutical Technology, and Health Research Institute (IDIS), Universidad de Santiago de Compostela, Santiago de Compostela, A Coruña, Spain.
Oncotarget. 2015 May 10;6(13):10950-63. doi: 10.18632/oncotarget.3459.
Glioblastoma tumor initiating cells are believed to be the main drivers behind tumor recurrence, and therefore therapies that specifically manage this population are of great medical interest. In a previous work, we synthesized controlled release microspheres optimized for intracranial delivery of BMP7, and showed that these devices are able to stop the in vitro growth of a glioma cell line. Towards the translational development of this technology, we now explore these microspheres in further detail and characterize the mechanism of action and the in vivo therapeutic potential using tumor models relevant for the clinical setting: human primary glioblastoma cell lines. Our results show that BMP7 can stop the proliferation and block the self-renewal capacity of those primary cell lines that express the receptor BMPR1B. BMP7 was encapsulated in poly (lactic-co-glycolic acid) microspheres in the form of a complex with heparin and Tetronic, and the formulation provided effective release for several weeks, a process controlled by carrier degradation. Data from xenografts confirmed reduced and delayed tumor formation for animals treated with BMP7-loaded microspheres. This effect was coincident with the activation of the canonical BMP signaling pathway. Importantly, tumors treated with BMP7-loaded microspheres also showed downregulation of several markers that may be related to a malignant stem cell-like phenotype: CD133(+), Olig2, and GFAPδ. We also observed that tumors treated with BMP7-loaded microspheres showed enhanced expression of cell cycle inhibitors and reduced expression of the proliferation marker PCNA. In summary, BMP7-loaded controlled release microspheres are able to inhibit GBM growth and reduce malignancy markers. We envisage that this kind of selective therapy for tumor initiating cells could have a synergistic effect in combination with conventional cytoreductive therapy (chemo-, radiotherapy) or with immunotherapy.
胶质母细胞瘤肿瘤起始细胞被认为是肿瘤复发的主要驱动因素，因此专门针对这一细胞群体的治疗方法具有重大医学意义。在之前的一项工作中，我们合成了经优化用于颅内递送骨形态发生蛋白7（BMP7）的控释微球，并表明这些装置能够阻止胶质瘤细胞系的体外生长。为了推动这项技术的转化发展，我们现在对这些微球进行更深入的探索，并使用与临床环境相关的肿瘤模型：人原发性胶质母细胞瘤细胞系，来表征其作用机制和体内治疗潜力。我们的结果表明，BMP7能够阻止那些表达受体BMPR1B的原代细胞系的增殖并阻断其自我更新能力。BMP7以与肝素和四臂聚醚嵌段共聚物形成复合物的形式被包裹在聚（乳酸-乙醇酸）微球中，该制剂可实现数周的有效释放，这一过程由载体降解控制。异种移植的数据证实，用负载BMP7的微球治疗的动物肿瘤形成减少且延迟。这种效应与经典BMP信号通路的激活同时出现。重要的是，用负载BMP7的微球治疗的肿瘤还显示出几种可能与恶性干细胞样表型相关的标志物下调：CD133(+)、少突胶质细胞转录因子2（Olig2）和δ胶质纤维酸性蛋白（GFAPδ）。我们还观察到，用负载BMP7的微球治疗的肿瘤显示细胞周期抑制剂表达增强，增殖标志物增殖细胞核抗原（PCNA）表达降低。总之，负载BMP7的控释微球能够抑制胶质母细胞瘤的生长并减少恶性标志物。我们设想，这种针对肿瘤起始细胞的选择性疗法与传统的减瘤治疗（化疗、放疗）或免疫疗法联合使用可能具有协同效应。
