磁性生物陶瓷人工椎体靶向治疗椎骨肿瘤的可行性研究与大动物试验

目的 研究应用磁性生物陶瓷人工椎体靶向治疗椎骨肿瘤的可行性。方法 选择2～4岁健康山羊4只，椎体切除后行“磁性生物陶瓷人工椎体置换术”。山羊术后于前小腿外侧皮下静脉注射^99MTc4^-标记的葡聚糖磁微粒(DMN)(0．1mg／kg体重)，L4区域应用医用磁导向定位仪，磁场强度为1T。ECT采集时间为：给药后0～1min内，每2s采集1次，共30次；此后，在给药后20，40，60，80min各采集1次，动态观察在磁场条件下,^99MTc4^-标记的DMN在靶区的富集情况；同时对心、肝、脾、肾和肺等脏器进行同步ECT采集显像，动态观察DMN在体内的分布情况。结果 在体外磁场的作用下，ECT显像显示给药40min后磁区出现^99MTc4^-标记的DMN富集，且富集的浓度随磁场作用的时间的延长而增高，80min时DMN在磁区的浓集继续增加。撤除外加磁场，DMN浓集随即消失。结论 在外磁场的作用下，具有顺磁性的磁性生物陶瓷的磁化强度升高，产生与体外磁场方向一致的体内小磁场，在体内、外磁场的联合作用下，具有超顺磁性的DMN浓集于磁性生物陶瓷人工椎体区域，可使局部定位更明确、具体，强化有效的靶向治疗效果，即形成“体腔内特定区域的靶向治疗”。

Feasibility of the targeting therapy as applied in the sheep after vertebra replacement with artificial magnetic bioceramic vertebral body

Objective To study the possibility and effect of the targeting therapy in sheep applied with artificial magnetic bioceramic vertebral body replacement and intravenous injection of the dextran magnetic nanoparticles. Methods Magnetic guidance of 99 M Tc - 4 labeled dextran nanoparticles was evaluated in sheep with the replacement of artificial magnetic bioceramic vertebral body in L 4. The dextran magnetic nanoparticle was administrated by intravenous injection. An outside magnetic field was applied in the back of L 4. The localization of the dextran nanoparticles was determined in vivo by ECT,and the distribution of dextran nanoparticles in liver, lung, spleen, and kidney were also investigated. Results It was shown that the dextran nanoparticles was highly reactive to magnetic field, and concentrated at the predetermined site. The radioactivity accumulation in other organs, especially in liver, was significantly reduced due to the presence of the outside magnetic field. When the magnetic field was removed, the radioactivity accumulation in the back disappeared. Conclusion The magnetic bioceromic has good paramagnetism and its intensity of magnetization could be raised when the extra corporeal magnetic field is applied. As a result, the local magnetic field is reinforced, and its direction is coincident with the extra corporeal magnetic field. Therefore the local reinforced targeting therapy could be formed around the area of the artificial magnetic bioceramic vertebral body when the dextran magnetic nanoparticles were attracted by the double magnetic field and concentrated in the target field.