Abstract
Various treatment methods for tracheal defects have been attempted, such as artificial implants, allografts, autogenous grafts, and tissue engineering; however, no perfect method has been established. We attempted to create an effective artificial trachea via a tissue engineering method using 3D bio-printing. A multi-layered scaffold was fabricated using a 3D printer. Polycaprolactone (PCL) and hydrogel were used with nasal epithelial and auricular cartilage cells in the printing process. An artificial trachea was transplanted into 15 rabbits and a PCL scaffold without the addition of cells was transplanted into 6 rabbits (controls). All animals were followed up with radiography, CT, and endoscopy at 3, 6, and 12 months. In the control group, 3 out of 6 rabbits died from respiratory symptoms. Surviving rabbits in control group had narrowed tracheas due to the formation of granulation tissue and absence of epithelium regeneration. In the experimental group, 13 of 15 animals survived, and the histologic examination confirmed the regeneration of epithelial cells. Neonatal cartilage was also confirmed at 6 and 12 months. Our artificial trachea was effective in the regeneration of respiratory epithelium, but not in cartilage regeneration. Additional studies are needed to promote cartilage regeneration and improve implant stability.
Highlights
Cartilage, and could not withstand the pressure during breathing
The scanning electron microscope (SEM) images revealed that the hydrogel containing epithelial cells on the inner layer and the hydrogel containing chondrocytes on the outer layer were printed on the boundary of the PCL layer (Fig. 1D)
On computed tomography (CT) images, we observed that the inner diameter of the graft site was significantly reduced in the control group (Fig. 3A)
Summary
Cartilage, and could not withstand the pressure during breathing. In addition, the surrounding tissue may unite with the stent and cause stenosis or haemorrhage[8]. One method involved fabricating and mounting of cylindrical implants[9,11] Since these implants cannot be combined with surrounding tissues, infection, dislodgement, immune reaction, migration, obstruction and other problems have occurred and epithelialisation has not progressed[12]. The most actively studied method for fabricating artificial trachea is tissue engineering, and biodegradable synthetic polymers are used to make tubular scaffolds. Due to the development of 3-dimensional (3D) printing technology, various attempts have been made to use this technology in tissue engineering[14] Biodegradable materials, such as polycaprolactone (PCL), polyglycolic acid (PGA), polylactic acid (PLA), and poly(lactic-co-glycolic) acid (PLGA), used in 3D printing have strengths similar to the tracheal cartilage; various attempts are being made to apply 3D printing technology to artificial trachea research[15]. An artificial trachea was implanted in a well-known trachea scaffold partial resection model[17], and respiration scoring, x-ray, computed tomography (CT), endoscopy, and histological examination were performed
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