Experimental Tracheal Replacement Using 3-dimensional Bioprinted Artificial Trachea with Autologous Epithelial Cells and Chondrocytes

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.

Breathing life into engineered tissues using oxygen-releasing biomaterials

“…Tissue engineering approaches can address the unmet demand for the replacement, repair, and regeneration of organs and tissues [4][5][6][7] . There has been remarkable success in the clinical translation of 3D tissueengineered constructs for repairing organs, such as the trachea 8,9 and lungs; 10 however, multiple challenges remain unaddressed. These challenges include (i) the preservation of high cell viability postimplantation, (ii) the unwanted immune response, (iii) the obstruction of cell signaling pathways, (iv) insufficient cell proliferation, and (v) low metabolic activity within the implanted scaffolds.…”

Choosing the Right Differentiation Medium to Develop Mucociliary Phenotype of Primary Nasal Epithelial Cells In Vitro

“…Regenerative medicine promises autologous and tailor-made tissue substitutes without the need of immunosuppression 5 . For this reason, more and more tissue engineered tracheal replacements have arisen in recent past 6,7 . Nevertheless, these strategies still face challenges regarding vascularization, mechanical stiffness and proper epithelization 8,9 .…”

Enhanced Biocompatibility of Multi-Layered, 3D Bio-Printed Artificial Vessels Composed of Autologous Mesenchymal Stem Cells

“…Also, a bio-printed conduit manufactured with endothelial cell-containing, 3% alginate and a porous PCL structure was found to exhibit the expression of cells after application of a simulation system reflective of hemodynamics for 2 weeks [13]. Finally, the results of an artificial tracheal study showed that 3% alginate mixed with autologous epithelial and chondrocytes could be printed with PCL and support cell viability, showing dead cells at levels less than 20% from the third day [11]. Accordingly, we hypothesized that the fabrication of artificial vessels that are small in diameter with biodegradable PCL, an appropriate content of alginate, and a sufficient amount of autologous cells would protect against graft failure stemming from thrombosis, neo-intimal hyperplasia, and immune rejection.…”

“…In studies using 3D bio-printing with alginate solutions, 3% alginate was deemed an appropriate concentration with which to protect against physical denaturation [10], compared to 2.5% alginate, which, despite chemical crosslinking with CaCl2, facilitated poor formation of the designed pattern [10,11]. In addition to use in the cardiovascular system, constructing a double-structured conduit combining bio-printed alginate hydrogels and a biodegradable polycaprolactone (PCL) scaffold has been found to be beneficial in applications for treating the cranial nervous system and airway track: In the conduit in which alginate containing neurons and a porous PCL scaffold were combined, a uniform cell distribution and the same proliferation rate as that in plate media were confirmed [12].…”