In the United States, joint disease affects more than 50 million people, causing pain, discomfort, and a lower quality of life. Some of this joint pain can be associated with focal cartilage defects. Unlike other bodily tissues, articular cartilage cannot self-repair these defects. Fortunately, scientists have been investigating tissue engineered cartilage, a repair technique that replaces missing or damaged cartilage with living tissue. In clinical trials tissue engineered cartilage has shown the ability to fill focal cartilage defects with collagen and proteoglycans and reduce joint pain. However, these constructs must also support and protect the joint from loading during everyday activities. Typically, only biochemical properties are used to assess the quality of these constructs. However, the role of articular cartilage in the joint is mechanical, therefore the mechanical properties of human tissue engineered cartilage could be a better predictor of implant success.

To predict the mechanical function of human tissue engineered cartilage, this thesis investigated multiple multiscale mechanical properties of constructs (aggregate modulus, hydraulic permeability, shear modulus, friction coefficients, and probability of buckling). With increasing growth prior to implantation, compressive properties and friction coefficients approached values similar to native articular cartilage. The shear modulus did not change with increased growth. This mechanical analysis of human tissue engineered cartilage showed that both global and local mechanical properties may be critical to construct success.

Once a baseline for the mechanics of human tissue engineered cartilage was established, this thesis investigated sources of variability in the constructs and techniques to improve the tissue. The largest source of mechanical variability comes from the autologous chondrocyte source. The use of induced pluripotent stem cells (iPSCs) was shown to be able to potentially replace the autologous chondrocyte cell source with an allogenic cell source. These analyses of manufacturing parameters and methods of improving the product will assist corporations to manufacture consistent, reliable, and cost-effective human tissue engineered cartilage.

Finally, other joints in the body, such as the temporomandibular joint (TMJ) may also benefit from human tissue engineered cartilage, but much less is known about healthy TMJ cartilage mechanics. Therefore, this thesis also showed TMJ tissues follow Stribeck curve behavior with some distinct properties compared to knee articular cartilage. Overall, this thesis enhanced our understanding of the mechanical function of cartilaginous tissues and the ability for these tissues to support loads and protect our joint from damage and pain.