Nrf2和TLR4协调作用对脂肪来源的干细胞促进自体脂肪移植成活的机制研究

Because of its obvious advantages autologous fat transplantation has become the most popular research areas of plastic surgery in recent years, but it cannot be widely used in clinic for it’s low survival rate, poor survival quality and the effection is difficult to predict after fat transplantation. Previous studies have found that fat graft survival were promoted with drug or hormone added in transplant fat. But it can not be used in clinical because of safety issues. Our recent studies found that adipose-derived mesenchymal stem cells (ADSCs) can significantly improve the survival of fat transplantation and regulated by TLR4 and Nrf2. But the specific mechanism of how to promote the survival of fat transplantation is unknown. From the preliminary study we presume: ADSCs can release a variety of cytokines to protect fat tissue under the regulation of TLR4 and Nrf2; At the same time the coordination of TLR4 and Nrf2 with each other in ADSCs promote angiogenesis of the transplanted adipose tissue; Finally, ADSCs multi-directional differentiation potential, made up for the loss of fat cells for transplantation. In order to prove this hypothesis and provide a new ideas for fat transplantation clinical, this project will study the specific molecular mechanism and control targets of how ADSCs promote fat graft survival through in vivo and in vitro experiments using gene knockout mouse Nrf2-/- and TLR4-/-.

自体脂肪移植因其优势明显，近年来已成为整形外科最热门的研究领域，但移植脂肪成活率低，成活质量不佳，移植后效果难以预测，致使其不能在临床上广泛应用。以往研究发现，向移植脂肪中加入药物或激素可促进脂肪移植成活，但由于存在安全隐患短期内不能用于临床推广。我们新近的研究发现脂肪来源的干细胞(ADSCs)能明显提高移植脂肪的存活率，且受Nrf2和TLR4调节，但具体机制尚不清楚。从前期预实验结果上我们推测：ADSCs加入后，在Nrf2和TLR4信号的调节作用下可释放多种细胞因子对脂肪细胞进行保护；同时Nrf2和TLR4信号对ADSCs进行调节可促进移植脂肪组织中血管生成；最后ADSCs的多向分化潜能，弥补了受损的脂肪细胞。为了证明本假说，本项目拟从体内和体外两方面，并借助敲基因鼠Nrf2-/-和TLR4-/-探讨ADSCs促进脂肪移植成活的具体分子机制和调控靶点，为脂肪移植的临床化提供新思路。

自体脂肪移植是一种有效的重建手术技术，但其成功受到移植环境炎症和高氧化应激的限制，传统单纯脂肪采集及注射技术存在着高吸收率、低存活率等不足。脂肪来源的干细胞(ADSCs)增加了脂肪移植物的存活，尽管其潜在机制尚不清楚。在这里，我们采用TLR4−/−和Nrf2−/−小鼠，探讨氧化应激和炎症对ADSCs体内外活力和功能的影响。研究表明，富集ADSCs的脂肪可抑制炎症细胞因子的产生、增强生长因子水平、下调NADPH氧化酶(NOX)1和4的表达、增加血管化、降低ROS的产生，从而增加脂肪移植存活率，其方式依赖于Toll样受体(TLR)-4和核因子红系2相关因子2(Nrf2)的表达。通过免疫组织化学分析可知，低氧环境可促进ADSCs的增殖，并上调ADSCs向血管内皮细胞的分化潜能。低氧诱导的ADSCs中炎症细胞因子、生长因子和NOX1/4上调，以及ROS的产生增加依赖于TLR4和Nrf2，同时增强了ADSCs促进内皮祖细胞迁移和血管生成的能力。免疫印迹分析表明，缺氧对ADSCs的影响受Nrf2抗氧化反应与NF-κB和TLR4介导的炎症反应之间的串扰调节。综上所述，我们的结果表明，ADSCs可以通过Nrf2和TLR4调节炎症和氧化反应来提高脂肪移植的存活率，这为提高ADSCs在细胞治疗中的应用提供了潜在的策略。