CXCR4基因转染联合VCAM-1抗体包被促MSCs归巢及其对实验性IBD小鼠肠黏膜修复机制研究

IBD is a non-specific inflammatory bowel disease, and its incidence might be related to genetic susceptibility and mucosal immune abnormalities. Currently, mucosal healing is considered as an important factor in predicting recurrence and keeping the remission. Recent studies showed that MSCs could not only promote the healing of the damaged intestinal mucosa, but also could correct the abnormal immune function. Our previous study showed that: MSCs located in the intestinal mucosa of IBD mice and then improved their survival rate by promoting the regeneration of mucosa and the regulation of immune. However, the limited number of MSCs' colonization in the intestinal mucosa limited its role to play. Based on our previous work, this project will initiate from homing factors, including chemokine and adhesion. Methods of CXCR4 gene transfected MSCs, VCAM-1 antibody coated MSCs, and both will be adopted to compare the localization of different modified MSCs in the damaged intestinal mucosa.In addition，we will also detect the mechanism of MSCs repairing in the perspective of proliferation, differentiation, angiogenesis, and immune regulation. This project might provide an ideal targeting method for MSCs transplantation for IBD and then improve the clinical efficacy, and thus lay the theoretical foundation for MSCs transplantation for IBD patients in the clinical treatment.

IBD 是一种非特异性肠道炎症性疾病，其发病可能与基因易感性和黏膜免疫异常有关。目前黏膜愈合被作为维持其缓解、预测复发的重要因子。新近文献报道MSCs在促损伤肠黏膜愈合的同时可矫正免疫功能的异常。前期研究表明MSCs可定植于IBD小鼠的肠道，并通过促其黏膜再生及免疫调节等机制提高存活率。但实验中发现 MSCs定植于损伤肠黏膜的数量有限，限制了其作用的发挥。因此，本项目拟在前期工作基础上，从MSCs归巢的两大要素即趋化和黏附着手，采用CXCR4基因转染，VCAM-1抗体包被及两者共修饰MSCs的方法，横向比较不同处理组MSCs定植于受损肠黏膜的数量及修复肠黏膜的能力；并从增殖分化、血管生成和免疫调节等角度深入探讨黏膜修复机制。有望为临床采取何种方式靶向MSCs到IBD损伤的肠黏膜进而提高疗效奠定理论基础。

炎症性肠病(Inflammatory bowel disease, IBD) 是一种非特异性肠道炎症性疾病，其发病可能与基因易感性和黏膜免疫异常有关。新近文献报道MSC在促损伤肠黏膜愈合的同时可矫正免疫功能的异常，但由于MSC定植于病变肠道的数量有限，限制了MSC的治疗效果。本课题拟构建IBD小鼠模型并构建骨髓间充质干细胞（Mesenchymal Stem Cell, MSC）、CXCR4 靶向性MSC(C-MSC)、VCAM1包被MSC(V-MSC)及CXCR4和VCAM1双重靶向的MSC(C-V-MSC)，比较四组MSC的生物学特性，通过体外迁移实验比较四组MSC的迁移率；后将四组MSC移植入IBD模型并设立对照,采用小动物活体成像、荧光标记、Y染色体示踪技术检测比较MSC在各组IBD小鼠中的定植定植情况。本研究成功地构建了四组MSC,证实了CXCR4基因转染及VCAM1抗体包被不影响MSC的生物学特性，通过体外实验证实了C-V-MSC组迁移率>V-MSC，C-MSC>MSC组，体内实验证实了接受四组MSC移植的IBD小鼠，症状表现、组织学及病理学检查及死亡率等均明显改善;体内定植实验表明(定植率V-C-MSC>V-MSC，C-MSC>MSC移植组)；肠道黏膜得到了再生修复。因此，为下一步从促进肠道干细胞增殖分化、调节肠道黏膜微环境、维持上皮屏障的完整性及调节全身及局部肠道黏膜免疫紊乱四个方面探讨四组MSC治疗实验性IBD 的机制奠定了基础。

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