Tendon and ligament repair: regeneration and maturation

The thesis constitutes the studies about the two aspects of tendon and ligament tissue engineering: regeneration and maturation. Injuries to tendon and ligament are among the most common injuries to the body, particularly in the young and physically active population. Associated with the problems of incomplete healing and recurrent injury, these injuries are not only responsible for large health care cost, but also result in lost work time and individual morbidity. Tissue engineering holds promise in treating these conditions by replacing the injured tissue with engineered tissue exhibited similar mechanical and functional characteristics. Collagen plays a central role in tendon and ligament regeneration, as collagen type I is responsible for more than 60% and 80% of the dry weigh of tendon and ligament structures, respectively. The hierarchical organization of collagen type I in bundles confers most of the mechanical properties of tendons and ligaments. Consequently, tendon or ligament tissue engineering studies are mainly focused on seeding cells into collagen gels. However, up to now, no cell-collagen constructs have been able to achieve sufficient mechanical properties and the complex architecture of the tendon and ligament is never fully reproduced. A major cause for low mechanical property of regenerating tendon or ligament is the slow maturation. The maturation of the engineered tissue is dominated by the maturation degree of extracellular matrix, such as collagen crosslink density. To