TGF-β受体抑制剂EW-7197载药金纳米颗粒涂层支架在支架相关狭窄的预防疗效及机制研究

Benign esophageal stricture is a challenging clinical condition. Its most common symptom is dysphagia, which could result in weight loss and malnutrition thereby affecting the patient’s quality of life. Stent placement is commonly performed to treat benign esophageal stricture, particularly those who are refractory to balloon dilation. It could dilate the stricture and ameliorate the symptom of dysphagia thereby improving the patient’s quality of life. However, stent-related tissue hyperplasia has limited its wide spread use and therefore, it is clinically necessary to overcome this obstacle. Nanofuntionalized stent-mediated local heat treatment has been considered as a promising approach to prevent stent-related tissue hyperplasia, but the long-term outcomes are unclear. In our pilot study, we found that, GNP-mediated local heating can significantly reduce stent-related tissue hyperplasia during a 4-week follow-up, but new granulation tissues were observed at 8-week follow-up. This may be the pathological consequence of the activation and proliferation of the remaining myofibroblast located in the bottom of the granulation tissue after local heat treatment, and indicates that further treatment may be required to prevent stent-related tissue hyperplasia in the long-term. EW-7197, an activin-like kinase 5 inhibitor, has been shown to be able to effectively suppress stent-related tissue hyperplasia by inhibiting the activity of TGF-β-Smad pathway. In the present study, we aim to investigate if EW7197-loading AuNPs-coated stent-mediated combination treatment of EW-7197 and local heat treatment would be more effective in preventing stent-related tissue hyperplasia in a rat model. Through our current study, we may provide basis for a novel stent therapy to treat benign esophageal stricture.

食管支架置入是目前治疗良性狭窄的常用方法。食管支架可显著扩张狭窄食管、改善吞咽困难症状，但支架相关狭窄限制支架的长期通畅性，严重影响了患者的生活质量。因此，亟需能有效减少支架相关狭窄的方法和手段。研究发现功能性金纳米涂层支架可通过局部光热效应显著减少大鼠食管支架相关狭窄，但前期研究随访观察时间短，无法评估长期疗效。本课题组的前期预实验发现，局部光热治疗短期内可有效减少支架相关狭窄，延长随访观察时间发现，术后周支架段食管可见新生肉芽组织，可能机制为局部热处理后基底部残存的成纤维细胞活化增殖，因此我们预测抗成纤维细胞活化增殖联合局部光热效应可能更有效减少支架相关狭窄。EW7917是特异性TGF-β受体1抑制剂，可通过抑制TGF-β-Smad通路活性抑制成纤维细胞增殖和活性。本研究拟采用新型EW-7197载药金纳米颗粒涂层支架在大鼠模型中探究EW7917联合光热效应在支架相关狭窄的疗效和机制。

支架相关狭窄是目前食管支架置入术面临的最大问题。本项目的主要研究内容为：① EW-7197/AuNPs涂层支架预防支架相关狭窄的有效性及安全性；② EW-7197/AuNPs涂层支架对食管组织内细胞外基质生成的影响；③ EW-7197/AuNPs涂层支架对食管组织内细胞凋亡及坏死的影响。成功制备EW-7197/AuNPs涂层支架后，将48只9周周龄的雄性SD大鼠（体重250~300g）随机分成4组，每组12只，麻醉各组大鼠后在透视下置入食管支架：A组置入普通裸金属支架，B组置入非载药金纳米颗粒涂层金属支架，C组置入载药金纳米颗粒涂层金属支架，D组置入载药金纳米颗粒涂层金属支架。食管支架置入后10天麻醉B组及D组大鼠，在透视下将近红外光发射光纤送至支架处，采用波长为808nm，功率为1.27W/cm2行单次局部照射60秒。食管支架置入后8周所有大鼠均存活且未出现并发症，处死大鼠后即刻取出支架段食管组织。评估支架段食管组织上皮细胞层数、粘膜下肉芽组织厚度、增生肉芽组织面积百分比、胶原蛋白沉积程度评分、结缔组织面积百分比后发现，与其他组相比，D组的肉芽组织增生和细胞外基质生成最少，有统计学意义（P<0.05）。评估支架段食管组织TUNEL阳性细胞百分比后发现，与其他组相比，D组的细胞凋亡最明显。本项目发现基于EW-7197/AuNPs涂层支架的TGF-β受体抑制剂联合局部光热效应在预防支架相关狭窄方面安全有效，该支架具有良好的应用前景。