Novel Freeze-Cast Bioactive Glass Scaffolds for Bone Repair

Missouri University Of Science & Technology, Rolla MO

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Linked publications & trials

Abstract

DESCRIPTION (provided by applicant): Porous scaffolds fabricated for bone repair and regeneration using current methods are often limited to low- stress applications because of inadequate mechanical strength. Freeze casting of suspensions has been widely used for the preparation of porous materials, but constructs prepared conventionally by this route often lack sufficient strength for load-bearing applications. The hypothesis of this R15 proposal is that by controlling particle concentration, freezing rate, and solvent composition, scaffolds with a combination of high compressive strength, high strain to failure, high porosity, and large pore size for tissue ingrowth can be created by a unidirectional freeze casting process. The focus of this work is to create bioactive glass scaffolds that could repair segmental defects in long bones, but the results are expected to have additional significant applications in bone repair and regeneration. Our preliminary work showed that bioactive glass constructs with compressive strengths of 25 1 3 MPa, strain to failure of >20%, porosity >50%, and pore size of 100-110 5m can be created by a unidirectional freezing casting route. Our aim is to create bioactive glass constructs with a larger pore size (100-200 5m), more favorable for bone ingrowth, while improving construct strength and maintaining high porosity. Our approach will be to (1) explore how the primary parameters in the unidirectional freeze casting route (particle concentration, freezing rate, and solvent composition) influence the microstructure and mechanical properties of bioactive glass constructs, and (2) evaluate the ability of the porous constructs to support bone ingrowth and biological integration with surrounding tissues in an animal model. Our long-term goal is to create custom bioactive glass implants that could replace intercalary defects in long bones, while releasing growth factors or antibiotics as required for the particular clinical application. The present R15 project will provide new information on (1) how to process bioactive glass constructs with the desired microstructural and mechanical characteristics, and (2) the ability of the implants to support bone ingrowth and to integrate with surrounding soft tissues. This R15 project is anticipated to lead to a future application (R01), in which the repair of long bone defects in animal models with custom bioactive glass implants will be intensely investigated. Additional goals to be pursued in conjunction with this research are (1) exposure of undergraduate and graduate students to cross-disciplinary research in materials science and biological sciences, which is critical to the development of new and improved biomaterials, and (2) strengthening current and future efforts in biomedical research and education at Missouri University of Science and Technology. PUBLIC HEALTH RELEVANCE: Current prosthetic materials and devices are often inadequate for treating severely traumatized bone and tissues, such as shattered limbs and broken bones resulting from serious accidents and combat wounds. The repair and regeneration of large defects in load-bearing bones require the design and development of porous implants having the right combination of mechanical, structural, and biological characteristics.