Scientists in Japan have used a 3D bioprinter to create fully functional artificial tracheas from living cells which have been successfully transplanted in rats. While they are not the first to use bioprinters to create artificial tracheas, this is the first time that viable artificial tracheas have been created without the use of scaffolds.
Scaffolds are usually required to add structural rigidity to ensure artificial 3D printed tracheas do not collapse when transplanted, although scaffolds have many disadvantages. They carry a risk of infection, they can cause irritation to surrounding tissues, and the scaffolds degrade over time. However, without the scaffolds, the artificial tracheas lack the stiffness and strength to maintain blood supply and keep the airway open.
The new technique uses the Cyfuse Biomedical Regenova 3D bioprinter, which has previously been used to print liver tissue and nerve tissue.
The researchers used three different cell types – mesenchymal cells from skeletal tissue, chondrocytes embedded in bone cartilage, and microvessel endothelial cells from rats. The researchers used the Kenzan method of printing: A 9×9 needle array that printed cell spheroids that had previously been cultured in U-well dishes. The spheroids were printed onto needles to keep them in position during the printing process. 384 of the spheroids were used to create each artificial trachea.
The 3D printed artificial tracheas were coated in chondrocyte growth medium and endothelial cell growths and matured in a bioreactor. Three of the printed tracheas were tested to failure using a DMT Tissue Puller and were found to have the necessary strength to be used in rats. Silicone stents were used to prevent the collapse of the tracheas until sufficient blood supply had developed.
Nine rats received artificial tracheas and were carefully monitored over a period of 23 days. Two of the nine rats experienced some wheezing due to retention of tracheal secretions, but the other seven rats showed no ill effects.
The researchers have hailed as a major success, and say the technique could potentially be used in humans.
The study – Scaffold-free trachea regeneration by tissue engineering with bio-3D printing –was conducted by researchers from Saga University and Nagasaki University and was recently published in the journal Interactive Cardiovascular and Thoracic Surgery.