联合过表达CXCR4基因的骨髓间充质干细胞和骨髓内皮前体细胞促进小体积移植肝再生及其机制的研究

供肝与受体间体积重量比过小将造成小体积综合征，引起移植肝再生障碍，甚至肝衰竭。骨髓间充质干细胞(MSC)能改善增生环境，促进肝再生。我们的前期研究发现过表达CXCR4的MSC（CXCR4-MSC）显著促进小体积移植肝再生。体外研究证实内皮前体细胞（EPC）与MSC分泌的因子在血管发生上存在互补效应。本申请拟建立30%大鼠肝移植模型，以性别交叉移植方式将骨髓来源的CXCR4-MSC、EPC输入动物体内，利用Y染色体特异Sry基因及病毒所携带的绿色荧光蛋白报告基因，观察它们在移植肝内分布、归巢和分化；检测炎症因子、肝再生信号通路蛋白等的表达及微血管的生成，探讨CXCR4-MSC和EPC通过旁分泌功能改善小体积移植肝再生微环境、调控肝再生的分子机制并寻找关键性效应因子。观察CXCR4-MSC和EPC是否具有协同效应，为联合应用CXCR4-MSC和骨髓来源的EPC促进小体积移植肝再生提供理论依据。

Reduced-size liver transplantation (RSLT), including living donor LT and split LT has, in part, alleviated the shortage of donor organs. However, if GRWR less than 0.8% or GV/SLV less than 40%, small-for-size syndrome (SFSS) would occur, liver regeneration was blocked, eventually leading to loss of liver function and liver failure. Marrow-mesenchymal stem cells (MSCs) have the potential to inhibit the death of hepatocytes and stimulate liver regeneration following acute and chronic liver injury via a paracrine mechanism, or directly differentiate into hepatocytes and repopulate the injured liver. Our previous study have proved that CXCR4-transduced MSCs are more responsive to SDF-1α in vitro, and CXCR4 overexpression enhanced MSC engraftment into small-for-size liver graft and improved its effect on proliferation of hepatocytes by a paracrine mechanism, providing a significant one week's survival benefit. Coculture of Endothelial Progenitor Cells (EPCs) and MSCs demonstrate a synergistic effect on new vessel formation. Bone marrow-derived EPCs express highly HGF. In our application for tender, rats that underwent 30% RSLT were received cross-gender rat MSC or/and EPC transplantation. Using the green fluorescent protein and the specific Sry gene on Y chromosome, their distribution of homing and differentiation after infusion were detected. Expression of TNF-α, IL-1β, IL-6, HMGB-1, IL-4, IL-10, ET-1, eNOS, HO-1，AP-1,NF-κB，c-Myc，STAT3、p-STAT3，ERK1/2、p-ERK1/2，JNK、p-JNK，cyclin D1 and miscrovesseldensity in the grafts were detected. And we investigate whether CXCR4-MSC and bone marrow-derived EPC improve the small-for-size liver graft regeneration by paracrine mechanism, and whether VEGF, HGF is the key effector of MSC and EPC paracrine function, respectively. We also explore whether there is a synergistic effect combined transplantation of CXCR4-MSC and bone marrow-derived EPC.