Orchestrating Bone Regeneration on Multiple Scales

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DESCRIPTION (provided by applicant): Bone fractures and defects result in more than 1.3 million surgical procedures each year in the United States. With current therapies, these fractures and defects can be restored to some degree, but far from an ideal solution. Although regenerative agents such as bone morphogenetic proteins (BMPs) have been shown to enhance bone formation when delivered to bone lesions in animal studies, results remain unpredictable for clinical applications. It is likely that the lack of an appropriate 3D scaffold that mimics the natural extracellular environment and supports bone regeneration is detrimental. It is also likely that inappropriate growth factor delivery (time, quantity, localization) confound the achievement of robust success. It is also likely that BMP alone is not sufficient but that additional factors and progenitor cells may be required in order to promote maximal bone regeneration. In addition, angiogenesis in parallel to tissue regeneration is critical to maintaining long-term viability and sustained function of regenerated tissues. Based on these analyses, we hypothesize that predictable and clinically relevant bone regeneration can be achieved by coordinating the biological activities (cells and regulating molecules) with structural cues (scaffold structures). We therefore propose a patient-specific, multi-scaled nano-fibrous scaffold for the delivery of bone marrow stromal cells (MSC) and multiple regenerative factors to engineer vascularized bone. The specific aims are: SA 1. Design "patient-specific" scaffolds with multi-scaled structures for bone regeneration. SA 2. Formulate NS to individually tune BMP? and bFGF release profiles in multi-scaled scaffolds in vitro; and determine the effects of scaffold structure, bFGF and BMP7 temporal release profiles on osteogenesis and angiogenesis in a mouse ectopic model. SA 3. Confirm that the multi-scaled and factor-releasing scaffolds (selected from Aims 1&2) afford a superior environment for vascularized bone regeneration in a rat critical defect model.