Abstract
The chondrocyte-agarose construct has been employed as an experimental model in the cartilage tissue engineering context. In this study, 15% cyclic compression was applied to the chondrocyte-agarose constructs during their culture period to examine its effects on the extracellular matrix (ECM) biosynthesis and mechanical characteristics of the regenerated cartilage tissue. Cylindrical chondrocyte-agarose constructs with a diameter of 4 mm and a height of 2.5 mm were prepared as test specimens. Chondrocytes isolated from metacarpal-phalangeal joint of steers were seeded in 1% Sigma type VII agarose or 4% Sigma type IX-A agarose to give an initial cell density of 1 x 107 cells/mL, and cultured in sterile culture medium (DMEM + 20% FBS) within a humidified tissue culture incubator. 15% cyclic compression was applied to test specimens at 1 Hz for 6 hour a day during their culture period by a mechanical loading system mounted within the tissue culture incubator. After culture periods of 1, 8, 15 and 22 days, mechanical properties of the cultured constructs, tangent modulus and equilibrium modulus, and glycosaminoglycan (GAG) biosynthesis were evaluated by the unconfined compression test and demethyl-methylene blue (DMMB) assay, respectively. The structural organization of the elaborated tissue was also examined morphologically by the confocal laser scanning microscopy (CLSM). Results indicated that the cyclic compression upregulated the GAG biosynthesis and the tangent modulus in both agarose constructs; however the upregulative effect on the development of collagen fiber network could not be identified. The GAG content and collagen network organization was significantly affected by the characteristics of the agarose construct. Consequently, the development of the mechanical stiffness was more significant in 1% type VII agarose compared to 4% type IX-A agarose.
