A novel 3D-printed silk fibroin-based scaffold facilitates tracheal epithelium proliferation in vitro

The functional epithelial regeneration is important for repairing tracheal defects. However, the potential of 3D-printed SF-based scaffolds for tracheal epithelial regeneration is still unknown. In this study, we developed a novel silk fibroin-based scaffold prepared by 3D printing of silk fibroin/hydroxypropyl methyl cellulose (SF/HPMC) thixotropic hydrogel and evaluated the tracheal epithelium proliferation on this scaffold in vitro. Combined with the freeze-dried technology, the 3D-printed SF/HPMC scaffolds had porous structures in the printed bars. After evaluation of their pore sizes, porosities, water contents and mechanical properties, the scaffolds were co-cultured with the normal human bronchial epithelial cell line (BEAS-2B) for seven days. We detected the BEAS-2B cells proliferation on the scaffolds using a CCK-8 assay, determined their mucin secretion and intercellular tight junction formation by immunofluorescence, as well as observed their cell viability and morphology by live/dead staining and scanning electronic microscopy. The results showed that the SF/HPMC scaffolds had good porosity, water content and mechanical properties. In addition, the BEAS-2B cells proliferated well on SF/HPMC scaffolds, during the seven-day co-culture, with high viability, mucin expression, and intercellular tight junction formation. In summary, these results demonstrated that the BEAS-2B cells could attach and proliferate on the 3D-printed SF/HPMC scaffolds, which were expected to have potential for facilitating tracheal epithelial regeneration.