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Introduction: Construction of engineered respiratory tract using tissue-engineered cartilage has not yet been reported. In order to generate artificial trachea using human chondrocytes obtained from tracheal cartilage, we investigated whether human tracheal chondrocytes can act as a cell source to fabricate engineered airway patches to augment stenotic parts of the trachea.Materials and Methods: After informed consent, chondrocytes were obtained from five patients who needed tracheal surgery. A small piece of resected tracheal cartilage was digested by collagenase type 2 for 3-4 h. This yielded chondrocytes, which were expanded in vitro and seeded onto biodegradable scaffolds; these were then implanted subcutaneously in athymic mice. The implanted constructs were retrieved 8 weeks later for histologic and biochemical analysis.Results: In monolayer cultures, chondrocytes proliferated well, showing a 100- to 1,000-fold increase in 1 month. Once expanded, the cells lost their original morphological and biologic characteristics, but the engrafted scaffold showed histologic and biochemical characteristics of cartilage. Viable chondrocytes and extracellular matrix were detected, and glycosaminoglycan (GAG) in vivo was present.Conclusions: Here we show that a small piece of human tracheal cartilage can generate sufficient chondrocytes in vitro and form tracheal cartilage architecture in an in vivo environment. [ABSTRACT FROM AUTHOR]

Abstract: Although tribological function is the most important mechanical property of articular cartilage, few studies have examined this function in tissue-engineered cartilage. We investigated changes in the frictional properties of cartilage regenerated from the inoculation of rabbit chondrocytes into fibroin sponge. A reciprocating friction-testing apparatus was used to measure the friction coefficient of the regenerated cartilage under a small load. The specimen was slid against a stainless steel plate in a water vessel filled with physiological saline. The applied load was 0.03N, the stroke length was 20mm, and the mean sliding velocity was 0.8mm/s. The friction coefficient of the regenerated cartilage decreased with increasing cultivation time, because a hydrophilic layer of synthesized extracellular matrix was formed on the fibroin sponge surface. The friction coefficient of the regenerated cartilage was as low as that of natural cartilage in the early stages of the sliding tests, but it increased with increasing duration of sliding owing to exudation of interstitial water from the surface layer. [Copyright &y& Elsevier]

The dynamic visco‐elastic properties of regenerated cartilage tissue were measured to evaluate its mechanical function during cultivation. Harvested chondrocytes from 4‐week‐old Japanese white rabbits were inoculated into fibroin sponge at a cell concentration of about 5×10[sup 7] cells/ml. Dynamic visco‐elasticity measurements were performed under compressive loading to evaluate the load bearing function of the articular cartilage. The dynamic modulus and the dynamic loss of the regenerated cartilage increased and the peak value of tanδ, as well as the frequency at the peak, decreased with increasing cultivation time. The pores of the fibroin sponge became filled with newly formed tissue as cultivation time increased. These changes in the visco‐elastic properties of the regenerated cartilage were compared with those of a model system, ethylene propylene diene monomer sponge with interstitial fluid, and appear to be a result of increased fluid flow resistance and internal loss. We conclude that the changes in the dynamic visco‐elastic properties of the regenerated cartilage were caused because of narrowing of the fluid path by synthesized extracellular matrix. [ABSTRACT FROM AUTHOR]