晚期骨肉瘤的疗效近30年几乎无进展，主要原因是肺转移发生率高，导致高死亡率。我们预实验发现CD133+CXCR4+ 骨肉瘤肿瘤干细胞具有高转移能力，推测其可能是促进骨肉瘤转移的种子细胞。因此，本课题将在前期研究的基础上，设计针对CD133+CXCR4+ 骨肉瘤肿瘤干细胞的综合治疗措施。构建分泌双特异单链抗体CD133/CD3-BiTE的溶瘤腺病毒ZD55/F35.CD133-BiTE，利用CD133+ 的间充质干细胞运载病毒至骨肉瘤肺转移病灶，释放病毒靶向感染骨肉瘤细胞，病毒复制裂解感染细胞的同时分泌双特异性抗体CD133/CD3-BiTE，激活T细胞，分泌穿孔素和颗粒酶，杀伤CD133+ 骨肉瘤干细胞，此外溶瘤病毒还可促进机体抗肿瘤免疫反应，多机制协同提高骨肉瘤肺转移的治疗效果，也为抗癌免疫联合治疗奠定基础。

The advance of osteosarcoma has made little progress in the past 30 years due to the high incidence and mortality of pulmonary metastasis. In our previous experiments, CD133+CXCR4+ osteosarcoma tumor stem cells were found to have high metastasis capacity and tumorigenicity, suggesting that they may be seed cells promoting lung metastasis of osteosarcoma.Therefore, on the basis of previous studies, this project will design treatment measures for CD133+CXCR4+ osteosarcoma tumor stem cells according to the comprehensive strategy of targeted treatment of tumor stem cells.Build secretion double antibody specific single CD133/CD3-BiTE soluble tumor adenovirus ZD55/F35.CD133-BiTE, use of ectomesenchymal stem cells carrying the virus of CD133+ to osteosarcoma pulmonary metastatic lesions, release the virus targeted osteosarcoma cells, ZD55/F35.CD133-BiTE copy cracking infected cells at the same time double antibody specificity CD133/CD3-BiTE, CD133/CD3-BiTE to activate T cells, secretion of perforin and particle enzyme, killing CD133+ osteosarcoma stem cells,In addition, oncolytic virus can promote the anti-tumor immune response, and multiple mechanisms can synergistically improve the therapeutic effect of lung metastasis of osteosarcoma.