Stavros Thomopoulos, Ph.D
Department of Orthopaedics Washington University
BJC - Institute of Health
11th floor - RM 11616
Phone: (314) 362-8597
The attachment of dissimilar materials is a major challenge because of the high levels of localized stress that develop at such interfaces. An effective biologic solution to this problem can be seen at the attachment of tendon (a compliant, structural “soft tissue”) to bone (a stiff, structural “hard tissue”). The unique transitional tissue that exists between uninjured tendon and bone is not recreated during healing, so surgical reattachment of these two dissimilar biologic materials often fails (e.g., the incidence of recurrent tears after rotator cuff repair may be as high as 94%). Tissue engineering strategies hold promise for improving the healing process and include the use of mechanical stimulation as a means to promote matrix synthesis. To develop successful strategies for tissue engineering at the tendon-to-bone insertion site we must first understand how the cells at the insertion respond to changes in their mechanical environment, i.e., their “mechanobiology.” We are interested in examining structure-function relationships at the natural tendon-to-bone insertion and the role of mechanobiology for the development, healing, and tissue engineering of the tendon-to-bone insertion site.
Our recent work has shown that: 1) the tendon-to-bone insertion is a functionally graded material with regard to its extracellular matrix composition, its structural organization, its mineral content, and its mechanical properties, 2) mechanical loading is necessary for the maturation of the insertion into a functionally graded material, 3) low levels of mechanical load are beneficial to tendon-to-bone healing while high levels of load are detrimental to healing, and 4) mechanobiology factors control collagen fiber orientation, matrix synthesis, and mechanical properties of tissue engineered constructs for tendon-to-bone repair. Taken together, these results provide guidance and a theoretical framework for our ongoing efforts to apply mechanobiologically-based tissue engineering strategies to improve healing and surgical repair of the tendon-to-bone insertion.