Development of a flexible 3D printed scaffold with a cell-adhesive surface for artificial trachea.

Trachea stents are widely used to treat stenosis arising from various trachea injuries. However, they are associated with inflammation, re-stenosis, and tracheal obstruction. Seeking to overcome these problems, the development of an artificial trachea using tissue engineering has been explored. However, the artificial trachea did not mimic the natural rigidity and flexibility of the trachea and provide the micro-environment necessary for re-epithelialization. In this study, we developed a thermoplastic polyurethane (TPU) trachea scaffold that possesses a restoration characteristic, using flexible 3D printed patterns, and an improved cell attachment performance, utilizing electrospun fibers. With the aim of enhancing flexibility, we compared two geometric tubes, one with a straight pattern (SP) and the other with a wave pattern (WP). Simulation results showed that the WP scaffold was more flexible than the SP scaffold. A tensile expansion and torsion experiment demonstrated lower tensile strength and elastic modulus, and higher elongation ratio and rotation angle of the WP scaffold. Addition of the electrospun layers increased the tensile strength and elastic modulus and decreased the elongation ratio and rotation angle of both the SP and WP scaffolds. The same trend was observed regardless of electrospinning. However, polycaprolactone (PCL)-based scaffolds displayed lower elongation ratio and rotation angle in simulations and experiments. Although the cell attachment capacity of TPU-based electrospun WP scaffolds was less than 10% that of PCL-based scaffolds, the former showed good initial cell attachment performance and their cell numbers increased by more than three times within a week. The improved biomechanical performance and cell affinity of the TPU trachea scaffold could be exploited in patient-customized grafts for trachea reconstruction.