磁性介孔磷灰石三维多孔支架的构建、骨诱导性及抗骨肉瘤性能研究

Osteosarcoma is the common primary malignant bone tumor, which is treated mainly by surgical removal in combination with radiotherapy and chemotherapy. The surgical removal of osteosarcoma may result in the biomechanical defects in weight-bearing bones and the recurrence of osteosarcoma due to the residual tumor cells. This project intends to design and fabricate magnetic mesoporous carbonated hydroxyapatite 3D porous scaffolds with alignment magnetic field, which not only repair effectively bone defects original from the surgical removal of osteosarcoma, but also can be used as drug delivery systems and ferromagnetic thermoseeds to kill the residual osteosarcoma cells. The main aims of this project is to study systematically the structure, morphology, fabrication mechanism and biological property of the magnetic mesoporous carbonated hydroxyapatite 3D porous scaffolds, to investigate the effect and mechanism of the alignment magnetic field on the morphology, adhesion, proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells, to demonstrate the efficacy for treatment of osteosarcoma by using the scaffolds as drug delivery systems and ferromagnetic thermoseeds, and to reveal the synergy effects among the biodegradability, formation of new bone, drug release property and anti-osteosarcoma performance after the multifunctional scaffolds are embedded in bodies. The completion of this project is expected to achieve a new synthesis technology of the magnetic mesoporous carbonated hydroxyapatite 3D porous scaffolds, and has important theoretical significance and clinical application value to develop new bone substitutes.

骨肉瘤是临床上常见的原发性恶性骨肿瘤，其治疗方法以手术切除为主，放疗、化疗等为辅。骨肉瘤在手术切除后会造成负重骨骼的生物力学缺陷，同时病灶内残留的肿瘤细胞容易引起复发。本项目设计和构建具有取向磁场的磁性介孔羟基磷灰石三维多孔支架，它不仅可以有效修复手术切除骨肉瘤引起的骨缺损，而且还可以作为药物传递系统和铁磁热籽，杀死局部残留的骨肉瘤细胞。本项目系统研究磁性介孔磷灰石三维多孔支架的结构、形貌、形成机理和生物学性能；揭示取向磁场影响人骨髓间充质干细胞的形态、附着、增殖和成骨分化的作用机制；探讨磁性介孔磷灰石多孔支架作为药物传递系统和铁磁热籽的抗骨肉瘤性能；阐明多功能支架材料植入体内后生物降解性、新骨形成、药物释放性能、抗骨肉瘤性能之间的协同作用机制。本项目的实施有望形成具有自主知识产权的磁性介孔磷灰石三维多孔支架的制备技术，对发展新型骨修复材料具有重要的理论意义和临床应用价值。

骨肉瘤是临床上常见的原发性恶性骨肿瘤，其治疗方法以手术切除为主，放疗、化疗等为辅。骨肉瘤在手术切除后会造成负重骨骼的生物力学缺陷，同时病灶内残留的肿瘤细胞容易引起复发。本项目采用冷冻干燥法制备磁性碳酸钙/壳聚糖三维多孔支架，然后置于磷酸缓冲溶液中通过溶解-沉积反应原位转化成磁性介孔磷灰石三维多孔支架。该多功能支架拥有三维贯通的大孔结构，其孔径主要分布在50-200 μm。磷灰石纳米片垂直排列在支架表面，而磁性锶铁氧体纳米颗粒均匀分布在三维多孔支架中。片状磷灰石是由大量的纳米粒子堆积形成，纳米粒子间堆积形成孔径为3.97 nm的狭缝状介孔结构。磁性介孔磷灰石三维多孔支架具有良好的细胞相容性，能够促进人骨髓间充质干细胞(hBMSCs)的粘附、铺展和增殖。磁性多孔支架中锶铁氧体纳米粒子所产生的取向磁场能够激活BMP-2/Smad/ RUNX2 信号通道，从而促进hBMSCs的成骨分化和新骨再生。磁性三维多孔支架中的大孔和介孔结构可以作为药物传递通道，提高材料对抗肿瘤药物分子的负载效率和释放性能。甲氨喋呤或者阿霉素等抗肿瘤药的可控释放能够有效杀死肿瘤细胞，加速骨肉瘤细胞凋亡。磁性多孔支架中的锶铁氧体纳米粒子对近红外光具有良好的光热响应性能。在近红外光（波长808 nm）照射下，磁性多孔支架迅速升温至42~50℃，并且升温速度随着铁氧体含量的增大而增大。细胞体外实验和动物体内实验结果表明：上述温度能够促进肿瘤细胞凋亡，并杀死肿瘤细胞。此外，借助磁性颗粒和介孔结构在生物学上的独特优势，还制备了磁性介孔生物玻璃多孔支架和磁性介孔硅酸钙多孔支架，用于治疗骨肉瘤术后引起的骨缺损。本项目开发了具有自主知识产权的磁性多孔支架材料，对发展新型骨修复材料具有重要的理论意义和临床应用价值。