仿生食管水凝胶复合纤维支架治疗食管瘘的实验研究

Treatment for esophagus fistula is complicated in clinical. Metal covered stent insertion is effective for the occlusion of esophagus fistula but if stent retrieved in a short period is likely to cause incomplete fistula healing while long-term stent insertion experiences risks of difficult stent retrieve, esophagus wall ulcer, bleeding or perforation. Tissue engineered esophagus has limited clinical application due to its unstable mechanical performance, needing open surgery and complicated inflammatory circumstance around the fistula. Stem cell is a kind of cell that has the characters of self-renewal and potential function to regenerate different types of cell and tissue. Mesenchymal stem cells (BSMC) is the most common kind of multipotential stem cells, which can be induced and differentiate into smooth muscle cell (SMC) by TGF-β1 factor. In present study, we intend to construct a new kind of biomimetic esophagus stent with hydrogel complex nano-fiber membrane covered. The stent framework can be biodegraded after provided support for a period time and the covered electrostatic spinning nano-fiber membrane may have the following unique functions: 1) providing immediate mechanical occlusion to the fistula; 2) hydrogel technique on the surface of membrane can load living BMSCs and keep its structure integrity and bioactivity during stent expansion; 3) realizing controlled release of TGF-β1 factor in situ to induce BMSCs differentiation into SMC phenotype; 4) highly orientation braided nano fibers can prompt SMC phenotype cells proliferation and migration in one direction to realize uniform coverage of the fistula. This kind of new stent will raise the chances of clinical healing for esophagus fistula and reduce its further recurrence.

食管瘘的治疗是临床棘手难题。金属覆膜支架封堵瘘口临床有效，但支架短期取出瘘口难以愈合，长期植入则造成取出困难、管壁溃疡、出血和穿孔风险。组织工程食管受限于机械稳定性差，需外科开放手术，瘘口感染环境复杂等因素临床应用受限。干细胞具有自我更新和再生各种细胞和组织的潜在功能，骨髓间充质干细胞（BMSCs）是多能干细胞常见的一类，TGF-β1因子诱导下可向平滑肌细胞（SMC）分化。本研究拟构建一种仿生食管水凝胶复合纤维支架，骨架在一定的时间内提供支撑后自行降解，支架表面裹覆静电纳米纺丝纤维膜，能够实现：1）即刻机械封堵食管瘘口；2）通过表面水凝胶技术负载活体BMSCs，保持细胞完整性和生物活性；3）实现原位TGF-β1因子长期控释，促进BMSCs向SMC表型分化；4）高度取向的编织结构，促进SMC表型细胞规则爬覆，实现瘘口均匀覆盖。上述支架有助于达到提高食管瘘病变临床愈合疗效和减少瘘口复发的目的。

食管瘘的治疗是当前临床面临的难题，除少量外科手术治疗外，介入支架治疗是食管瘘治疗的常见方案，其中最常见的是应用金属覆膜支架。然而，虽然封堵瘘口在短期内效果尚佳，但支架取出后瘘口却难以愈合，长期的植入往往导致取出困难、溃疡、出血甚至穿孔等并发症。新兴的组织工程食管受限于较差的机械稳定性、需要外科开放手术干预、瘘口感染环境复杂等因素而收到限制，本研究就使用了可降解的聚二恶烷酮（PDO）材料作为支架骨架，使用聚乳酸-聚羟基乙酸（PLGA）静电纺丝形成支架覆膜，并在覆膜外包裹载有自体骨髓间充质干细胞（BMSCs）的GelMA水凝胶，利用纳米纤维膜缓慢释放TGF-β1细胞因子，诱导BMSCs分化为SMC表型，并借助纤维取向排列使瘘口均匀覆盖。结果标明，PDO材料、纤维膜、GelMA均具有较好的生物相容性，其降解过程稳定可控，能够在体内全程提供足够的支撑力，缓慢释放的TGF-β1因子可诱导BMSCs分化，干细胞α-SMA表达显著提升。同时，兔食管瘘模型顺利建立，仿生食管水凝胶复合纤维支架释放后，能够即刻机械封堵食管瘘口，并能在随访期间有效避免不良并发症，最终从组织学上实现了对食管的修复。本课题借助了材料学领域的水凝胶技术、微溶胶静电纺丝技术，结合了结合了介入支架技术，有助于提高食管瘘病变愈合、减少瘘口复发及并发症，为食管瘘的治疗提供了新的方向，具有临床转化的潜力。