PD-L1与DTX1基因高效修饰MSC治疗肝移植后T细胞介导胆道平滑肌损伤的多模态报告基因成像研究

肝移植是终末期肝病的首选疗法，移植后T细胞介导胆道平滑肌损伤较难治疗。间充质干细胞（MSC）的低免疫调节力、低平滑肌细胞分化率、低归巢率、难活体示踪等特性限制MSC疗效。前期研究示SPIO标记因细胞分裂而MR信号减弱（Eur Radiol, IF3.97）；亦证实Fth基因能稳定、持久示踪MSC，DTX1基因能促MSC分化为平滑肌细胞（Mol Imaging Biol, IF3.47）。本研究拟利用正电荷纳米囊泡的免疫原性低、基因转染率高、生物安全性好等优点，拟将前期合成纳米囊泡负载PD-L1基因、DTX1基因、Fth基因、红色荧光蛋白mScarlet基因、促归巢CD44基因高效修饰MSC，进而抑制T细胞增殖，促进MSC成平滑肌细胞分化，实现治疗肝移植后T细胞介导胆道平滑肌损伤；提高MSC积聚铁能力，表达荧光蛋白，实现稳定、持久的MR光学多模态成像，并促进MSC自主归巢，增强活体示踪效果。

Liver transplantation is the preferred treatment for end-stage liver disease, and it is difficult to treat the T cells mediate biliary smooth muscle injury after transplantation. Mesenchymal stem cells (MSC) with low immunomodulatory regulation, low smooth muscle cell differentiation rate, low homing rate and more difficult to trace in vivo limit the curative effect. The SPIO can be diluted in dividing cells, resulting in a large degree of signal loss on MRI (European Radiology, IF=3.97). It is confirmed that Fth gene can steadily and persistently trace MSC, and DTX1 gene promotes MSC to differentiate into smooth muscle cell (Mol Imaging Biol, IF=3.47). Cationic nanovesicle have some advantages including low immunogenicity, high gene transfection rate, and good biological safety. This study intends to use the pre-synthesized cationic nanovesicle loaded with PD-L1 gene, DTX1 gene, Fth gene, red fluorescent protein mScarlet gene, and promote homing CD44 gene to effectively modify the MSC, so that the MSC can inhibit T cell proliferation, promote MSC differentiation into smooth muscle cell, and treat the T cells mediate biliary smooth muscle injury after liver transplantation. Meanwhile, multi-genes modified MSC can enhance the ability of accumulating iron, express fluorescent protein, achieve stable and durable MR-optical multimodality imaging, and enhance the effect of in vivo tracing by promoting autonomous homing.