Tang Qiu-sha, Zhang Dong-sheng, Cong Xiao-ming, Wan Mei-ling, Jin Li-qiang
School of Clinical Medical Science, Southeast University, Nanjing 210009, China.
Biomaterials. 2008 Jun;29(17):2673-9. doi: 10.1016/j.biomaterials.2008.01.038. Epub 2008 Apr 8.
One of the main advantages of gene therapy over traditional therapy is the potential to target the expression of therapeutic genes in desired cells or tissues. To achieve targeted gene expression, we developed a novel heat-inducible gene expression system in which thermal energy generated by Mn-Zn ferrite magnetic nanoparticles (MZF-NPs) under an alternating magnetic field (AMF) was used to activate gene expression. MZF-NPs, obtained by co-precipitation method, were firstly surface modified with cation poly(ethylenimine) (PEI). Then thermodynamic test of various doses of MZF-NPs was preformed in vivo and in vitro. PEI-MZF-NPs showed good DNA binding ability and high transfection efficiency. In AMF, they could rise to a steady temperature. To analyze the heat-induced gene expression under an AMF, we combined P1730OR vector transfection with hyperthermia produced by irradiation of MZF-NPs. By using LacZ gene as a reporter gene and Hsp70 as a promoter, it was demonstrated that expression of a heterogeneous gene could be elevated to 10 to 500-fold over background by moderate hyperthermia (added 12.24 or 25.81 mg MZF-NPs to growth medium) in tissue cultured cells. When injected with 2.6 or 4.6 mg MZF-NPs, the temperature of tumor-bearing nude mice could rise to 39.5 or 42.8 degrees C, respectively, and the beta-gal concentration could increase up to 3.8 or 8.1 mU/mg proteins accordingly 1 day after hyperthermia treatment. Our results therefore supported hyperthermia produced by irradiation of MZF-NPs under an AMF as a feasible approach for targeted heat-induced gene expression. This novel system made use of the relative low Curie point of MZF-NPs to control the in vivo hyperthermia temperature and therefore acquired safe and effective heat-inducible transgene expression.
基因治疗相对于传统治疗的主要优势之一在于，它有潜力将治疗性基因的表达靶向到所需的细胞或组织中。为了实现靶向基因表达，我们开发了一种新型的热诱导基因表达系统，该系统利用锰锌铁氧体磁性纳米颗粒（MZF-NPs）在交变磁场（AMF）下产生的热能来激活基因表达。通过共沉淀法获得的MZF-NPs首先用阳离子聚乙烯亚胺（PEI）进行表面修饰。然后在体内和体外对不同剂量的MZF-NPs进行了热力学测试。PEI-MZF-NPs表现出良好的DNA结合能力和高转染效率。在AMF中，它们能够升至稳定温度。为了分析AMF下热诱导的基因表达，我们将P1730OR载体转染与MZF-NPs照射产生的热疗相结合。以LacZ基因作为报告基因，Hsp70作为启动子，结果表明，在组织培养细胞中，通过适度热疗（向生长培养基中添加12.24或25.81 mg MZF-NPs），异源基因的表达可在背景基础上提高10至500倍。当注射2.6或4.6 mg MZF-NPs时，荷瘤裸鼠的体温可分别升至39.5或42.8摄氏度，热疗处理1天后，β-半乳糖苷酶浓度相应地可增加至3.8或8.1 mU/mg蛋白质。因此，我们的结果支持在AMF下MZF-NPs照射产生的热疗作为一种靶向热诱导基因表达的可行方法。这个新系统利用了MZF-NPs相对较低的居里点来控制体内热疗温度，从而实现了安全有效的热诱导转基因表达。
