间充质干细胞经后肠系膜动脉灌注联合吡非尼酮治疗大鼠直肠放疗相关纤维化的实验研究

Neo-adjuvant chemoradiotherapy is an important part of the combined modality therapy for rectal carcinoma, but the radiation-induced fibrosis of peri-rectal soft tissue and the proximal colon can affect the defecation function of the patients with sphincter preservation operation. Currently, it is a tough issue to handle radiation-induced fibrosis. This study will construct the rat model of radiation-induced rectal fibrosis, and the therapeutic effect of the mesenchymal stem cells infused via posterior mesenteric artery and pirfenidone on rat model will be studied. Multiphoton biopsy technique will be applied to analyze the dynamic change of the fibrosis of rat model during the intervention. And with other experimental methods will be applied to evaluate the effect of mesenchymal stem cells and pirfenidone on radiation-induced rectal fibrosis in rat model. Multiphoton biopsy technique is an advanced medical spectral imaging technique with the ability to realize the real-time and pathological-level examination on living body. Our previous study showed that this technique can be used to analyze the change of the collagen in the fibrotic tissue. In this study, mesenchymal stem cells will be infused via posterior mesenteric artery, which may improve the organ-targeted stem cell distribution. This study will further research the effect of new anti-fibrosis drug, Pirfenidone, and if it could improve the anti-fibrosis of mesenchymal stem cells or not. This study will provide the theoretic supports for the clinical application of mesenchymal stem cells and pirfenidone on the radiation-induced fibrosis.

直肠癌新辅助放化疗是直肠癌综合治疗的重要组成部分，但放疗可导致直肠周围软组织及临近结肠发生纤维化，这些纤维化的组织可影响保肛患者术后排便功能。目前对于防治放疗后的组织纤维化是一个难题。本课题将构建盆腔放疗后的直肠纤维化大鼠模型，应用间充质干细胞经后肠系膜动脉灌注联合吡非尼酮研究放疗相关纤维化的治疗效果。实验应用多光子活检技术动态观察纤维化的干预过程，并结合其他多种实验方法探讨间充质干细胞及吡非尼酮对于放化疗后软组织纤维化的治疗效果。多光子活检技术是一种先进的医学光谱成像技术，其有望用于实时、活体病理检查，前期研究发现该技术可有效分析纤维化组织中胶原纤维的变化。本课题经大鼠的后肠系膜动脉灌注间充质干细胞，有望提高干细胞输注的器官靶向性。本实验进一步研究联合抗纤维化新约——吡非尼酮是否能进一步提高间充质干细胞的疗效。该研究可为间充质干细胞及吡非尼酮的临床治疗放疗相关纤维化提供理论支持。

本研究构建大鼠直肠放射性纤维化的动物模型，探讨骨髓间充质干细胞与吡非尼酮对放射性肠纤维化的疗效。本研究主要结果如下：（1）体内实验表明，吡非尼酮可减轻大鼠放射性肠纤维化。该研究证实吡非尼酮的抗纤维化机制主要通过抑制主要通过抑制smad2和smad3的磷酸化，抑制TGFβ1-smad-CTGF轴。（2）体外实验表明吡非尼酮可通过抑制smad2、smad3的磷酸化，和抑制PI3K/AKT轴，调节大鼠和人的肠成纤维细胞增殖和凋亡。（3）动脉注射间充质干细胞后容易发生血肿，且不能多次注射，故改用股静脉多次注射间充质干细胞，初步观察到可能减轻大鼠放疗后直肠溃疡形成，但与吡非尼酮协同逆转纤维化作用不够明显。（4）多光子活检用于评估大鼠放射性肠纤维化无需染色，与病理切片Manson染色具有较好的一致性。这一结果为多光子活检评估放射性纤维化奠定基础，将来有望实现实时活检，指导外科手术肠切除范围。（5）本研究发表SCI论文3篇，在投2篇，本研究支持培养了1名博士和1名硕士研究生。

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