The regeneration of functional epithelial lining is critical for artificial grafts to repair tracheal defects. Although silk fibroin (SF) scaffolds have been widely studied for biomedical application (e.g., artificial skin), its potential for tracheal substitute and epithelial regeneration is still unknown. In this study, we fabricated porous three-dimensional (3D) silk fibroin scaffolds and cocultured them with primary human tracheobronchial epithelial cells (HBECs) for 21 days in vitro. Examined by scanning electronic microscopy (SEM) and calcein-AM staining with inverted phase contrast microscopy, the SF scaffolds showed excellent properties of promoting cell growth and proliferation for at least 21 days with good viability. In vivo, the porous 3D SF scaffolds (n = 18) were applied to repair a rabbit anterior tracheal defect. In the control group (n = 18), rabbit autologous pedicled trachea wall without epithelium, an ideal tracheal substitute, was implanted in situ. Observing by endoscopy and computed tomography (CT) scan, the repaired airway segment showed no wall collapse, granuloma formation, or stenosis during an 8-week interval in both groups. SEM and histological examination confirmed the airway epithelial growth on the surface of porous SF scaffolds. Both the epithelium repair speed and the epithelial cell differentiation degree in the SF scaffold group were comparable to those in the control group. Neither severe inflammation nor excessive fibrosis occurred in both groups. In summary, the porous 3D SF scaffold is a promising biomaterial for tracheal repair by successfully supporting tracheal wall contour and promoting tracheal epithelial regeneration.

中文翻译：

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多孔三维丝素蛋白支架气管上皮再生体外和体内

功能性上皮衬里的再生对于人工移植物修复气管缺损至关重要。尽管已经针对生物医学应用（例如人造皮肤）对丝素蛋白（SF）支架进行了广泛研究，但其在气管替代物和上皮再生方面的潜力仍然未知。在这项研究中，我们制造了多孔的三维（3D）的丝素蛋白支架和与原代人共同培养他们的气管支气管上皮细胞（HBEC的），持续21天的体外。通过扫描电子显微镜（SEM）和钙黄绿素-AM染色以及反相对比显微镜检查，SF支架显示出优异的促进细胞生长和增殖至少21天的特性，并具有良好的生存能力。在体内，多孔3D SF支架（n= 18）应用于修复兔前气管缺损。在对照组（n = 18）中，原位植入没有上皮的兔自体带蒂气管壁（理想的气管替代物）。通过内窥镜检查和计算机断层扫描（CT）扫描观察，两组的修复气道段在8周间隔内均未见壁塌陷，肉芽肿形成或狭窄。SEM和组织学检查证实了多孔SF支架表面上的气道上皮生长。SF支架组的上皮修复速度和上皮细胞分化程度均与对照组相当。两组均未发生严重炎症或过度纤维化。总之，多孔3D SF支架通过成功地支撑气管壁轮廓并促进气管上皮再生，是一种有前景的生物材料，可用于气管修复。