摘要：
Objective:To study the therapeutic effect of a novel double-target system,in which human umbilical cord-derived MSCs were used as vehicles to deliver fusion protein scFvCD20:sTRAIL to non-Hodgkin ’ s lymphoma. Methods: The traditional methods in molecular biology were used to construct lentivirus expression vectors pLenR. scFvCD20: sTRAIL and contrast vectors. Human umbilical cord-derived MSCs ( HUMSCs ) were labeled with the copGFP by transducing with pseudo viral particles which had been packaged in 293T cells with four plasmid-lentivirus packaging system. Fusion protein scFvCD20:sTRAIL were secreted from MSC. scFvCD20:sTRAIL after that HUMSCs were infected by pseudo viral particles. CCK8 assay was applied to detect the antigen-restricted cell death induced by scFvCD20:sTRAIL in CD20-positive BJAB and Raji cells as well as CD20-negtive Jurkat cells and human normal peripheral blood mononuclear cells (PBMCs). To evaluate the therapeutic effect of MSC. scFvCD20:sTRAIL in vivo,ge-netically modified HUMSCs were intravenously injected into tumor-bearing mice with BJAB cells. The volume of tumor was measured every three days, and the inhibition ratio of tumor was calculated according to tumor volume. Results: Lentivirus expression vectors pLenR. scFvCD20:sTRAIL, pLenR. ISZ:sTRAIL, pLenR. scFvCD20 and pLenR. CopGFP were successfully constructed and these constructs could be expressed stably in HUMSCs by lentivirus transduction. scFvCD20:sTRAIL fusion protein produced a potent inhibition of cell proliferation in CD20-positive BJAB cells,moderate inhibition of the growth of Raji cells,and weak inhibition in CD20-negtive Jurkat cells when compared with ISZ-sTRAIL treatment,and it had no effect on normal human peripheral blood mononuclear cells (PBMCs). The MSC. scFvCD20:sTRAIL treatment significantly inhibited the tumor growth when compared with those treated with MSC. ISZ-sTRAIL. Conclusion: A double-target therapeutic system is well established, in which HUMSCs migrated to tumor site, secreted a novel fusion protein scFvCD20:sTRAIL,and thus locally concentrated scFvCD20:sTRAIL extended antigen-restricted anti-tumor activity. The engineered HUMSCs secreting scFvCD20:sTRAIL showed potent effect on inhibiting tumor growth in BJAB lymphoma malignancy,which may play an essential role in the clinical research .%目的：：探讨脐带间充质干细胞运载scFvCD20：sTRAIL融合蛋白的新型双重靶向系统对CD20+ BJAB细胞的生长抑制作用。方法：采用传统分子生物学技术构建 pLenR. scFvCD20：sTRAIL、pLenR. ISZ-sTRAIL、pLenR. scFvCD20及pLenR. copGFP四种慢病毒表达载体,利用四质粒慢病毒包装系统于293T细胞中包装慢病毒颗粒,并感染人脐带组织来源的MSCs( HUMSCs),使其稳定表达融合蛋白。于体外采用CCK8细胞增殖抑制实验检测scFvCD20：sTRAIL融合蛋白对CD20阳性BJAB细胞和Raji细胞、CD20阴性Jurkat细胞以及正常人外周血单个核细胞( PBMCs)的生长抑制作用。建立NOD/SCID鼠BJAB细胞皮下移植瘤模型,将MSC. scFvCD20：sTRAIL经尾静脉注射入小鼠体内,每3 d测量瘤体积,根据肿瘤体积计算抑瘤率。结果：成功构建了慢病毒表达载体pLenR. scFvCD20：sTRAIL、 pLenR. ISZ-sTRAIL、pLenR. scFvCD20及pLenR. copGFP,且经慢病毒感染可在HUMSCs中稳定表达。体外实验显示,scFvCD20：sTRAIL融合蛋白可不同程度地提高对CD20阳性BJAB和Raji细胞的生长抑制作用,而对CD20阴性Jurkat细胞的生长抑制作用降低；而且不影响PBMCs的生长。体内实验表明, MSC. scFvCD20：sTRAIL可显著抑制BJAB淋巴瘤的生长,初始治疗后第24天,抑瘤率达65.2%,与MSC. ISZ：sTRAIL治疗组比较(抑瘤率为52.7%),具统计学差异(P<0.05)。结论：建立了HUMSCs运载scFvCD20：sTRAIL融合蛋白的双重靶向治疗系统,HUMSCs可向BJAB淋巴瘤部位归巢并表达分泌scFvCD20：sTRAIL融合蛋白,后者在局部经scFvCD20的二次导向发挥CD20特异性抑瘤作用。为MSCs作为肿瘤靶向治疗载体在临床中的应用提供了理论依据。
