This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
RESEARCH EFFORT: The attachment of dissimilar materials is a major engineering challenge because of the high levels of localized stress that develop at such interfaces. An effective biologic solution to thisproblem 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. We propose to reverse engineer the tendon-to-bone insertion to guide development of synthetic and biologically-derived graded materials. Two projects will be explored:
Area 1: Mechanisms of stress transfer in functionally graded biologic materials. The specific aim is to determine the mechanisms for stress transfer at the tendon-to-bone interface (a functionally graded biologic material) by studying the gradation in: (1) mechanical properties, (2) fibrocartilage content, and (3) mineral content and structure at the micro- and nano- scales.
Area 2: Tissue engineering of functionally graded biologic materials. The specific aim is to synthesize functionally graded biologic materials using collagen matrices and cells. We seek to achieve a gradation in mechanical properties through gradations in: (1) bio-mineral, and (2) fibrocartilage.
EDUCATIONAL EFFORT: The proposed educational activities are designed to introduce biomechanics to students at all levels, from elementary school to graduate school. The rotator cuff tendon-to-bone insertion site will be used as a platform to present the concept of functionally graded materials to all students. The educational activities in which the PI will participate over the next five years have the specific goals of: (1) introducing biomechanics to elementary school students, (2) inspiring female middle school students to enter careers in science and engineering, (3) educating the community on how mechanics principles underlie the physiologic outcomes in rotator cuff injury and repair, (4) teaching the concept of graded biologic materials to undergraduate and graduate engineering students, and (5) exposing undergraduate and graduate students to research topics related to graded biologic materials.
INTELLECTUAL MERIT: The PI seeks to advance the knowledge of functionally graded biologic materials. The research will advance the field by introducing an established concept (i.e., graded materials) to a new field (i.e., biomedical engineering). This will result in a better understanding of graded biologic materials and will lead to the synthesis of functionally graded materials. The PI has published 17 papers (out of a total of 26) and received numerous grants in the area. He has also received the Y.C. Fung Young Investigator award in recognition of his work. In addition, he has performed pilot experiments and calculations using available resources to show that all of his ideas are achievable within the 5-year course of the proposal.
BROADER IMPACTS: The coupled research/education proposal will (1) expose students at all levels to biomechanics concepts, and (2) expose engineering students to the concept of graded materials in biology. Educational activities will have a broad impact by targeting multiple populations, including elementary school students, female middle school students, and the community. The research will lead to an understanding of the mechanisms which aid transfer of load at biologic attachments and to an application of this knowledge for synthesis of functionally graded matrices. This knowledge will have a direct impact in medical applications (e.g., to enhance tendon-to-bone healing) as well as engineering applications (e.g., to design better airplane wing attachments).
