BIOPOLYMER SCAFFOLD AFFECTS MECHANICAL AND STRUCTURAL PROPERTIES OF TISSUE-ENGINEERED CONSTRUCTS FOR TENDON AND LIGAMENT REPAIR

More than $57 billion dollars are spent annually to treat tendon and ligament injuries in the U.S. (Andersson et al., AAOS, 2008). Tissue grafts are typically used to repair these damaged structures. However, osteoarthritis rates are equally high among individuals who have undergone reconstructive knee surgery compared to those who have not (von Porat et al., Ann. Rheum. Dis., 2004), suggesting that current surgical techniques do not restore normal function to the damaged joint. Tissue engineering strategies have shown efficacy in improving tendon repair using cell-seeded tissue-engineered constructs (TECs) by restoring functional tissue mechanical properties (Butler et al., J. Ortho. Res., 2008). The cell membrane acts as a transmitter of environmental conditions to the cell nucleus, which affects gene expression. It is important to understand how TEC material affects cellular response to ensure the safety and efficacy of tissue-engineered repairs. Collagen and fibrin materials are naturally occurring biopolymers, allow for flexibility in construct design, and can be remodeled by cells. This study compared TEC mechanical properties, TEC structure and gene expression patterns of cells seeded in fibrin and type I collagen hydrogels over time in culture. Paradoxically, results show that the more compliant fibrin actually results in a mechanically stronger TEC and is structurally more similar to native tendon tissue than a collagen TEC. This study suggests that fibrin may be a better candidate for tissue-engineered repairs and illustrates the importance of understanding the biological relationships between cells and materials to improve tendon repair. [NSF IGERT 0333377]