| Functional tissue engineering uses the knowledge of native articular cartilage to produce viable, cell-based tissue substitute. To this end, this dissertation focuses on characterizing and optimizing the material and biochemical properties of chondrocyte-seeded constructs subjected to dynamic loading and various culture media.;The major findings of this dissertation include:;1. Chondrocyte-seeded constructs were found to develop inhomogeneously. Although loading (3 hours/day) increased the overall material properties, the axial profile of the local material properties follows that of the free-swelling samples (21 hours/day). That is, the constructs were stiffest on the edge and softest in the center.;2. Less GAG and collagen were produced in central cores than in the annuli. Greater differences in biochemical content with loading were observed in central cores, with annuli being generally more similar. There were no significant differences in the mechanical properties of the cores and the annuli. Coring reduced the observed correlation between the biochemical and mechanical properties, suggesting that differences in the moduli of the cores and annuli may have been masked by the resultant disruption to the collagen matrix.;3. Chondrocyte-seeded constructs exhibited tension-compression nonlinearity reminiscent of native articular cartilage. Dynamic loading improved the tensile modulus, which may be due in part to the observed increase in the structural organization of the collagen network and type II collagen content relative to free-swelling controls.;4. For chondron-seeded (chondrocyte plus pericellular matrix) constructs, low chondron seeding density hindered matrix development relative to isolated chondrocyte-seeded controls, especially in response to loading. At high chondron seeding density, native and de novo-generated chondron-seeded construct development was similar to chondrocyte-seeded constructs.;5. To reduce our dependence on high concentrations of animal sera, we have investigated the use of low serum/ITS+ media in our culture system. In free-swelling culture, media supplementation with low serum/ITS+ is sufficient for producing constructs with properties similar to those grown in high serum media. In dynamic loading culture, the chondrocytes required priming in high serum media before culturing in low serum/ITS+ media.;The studies conducted for this dissertation combined cartilage biology and bioengineering techniques to increase our understanding of the role and effects of dynamic loading on the spatio-temporal development of material and biochemical properties of chondrocyte-seeded agarose constructs. This information can aid efforts to further optimize approaches for the functional tissue engineering of articular cartilage. |
