biomimetic Hydrogel/apatite Nanocomposite Scaffolds for Bone Regeneration
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0897-J07-03.1
Biomimetic Hydrogel/Apatite Nanocomposite Scaffolds for Bone Regeneration Esmaiel Jabbari Department of Chemical Engineering University of South Carolina Columbia, SC 29208, U.S.A. ABSTRACT Bone is a composite material consisting of aqueous gel and mineral phases. The aqueous gel phase gives bone its form and contributes to its ability to resist tension, while the mineral component resists compression. The combination of a hard inorganic phase and an elastic gel network provides bone with unique mechanical properties as well as a medium for diffusion and release of biologically active agents and it also facilitates communication with the cellular environment. A tissue engineered synthetic biomaterial as a scaffold for bone regeneration should provide temporary structural support to the reconstructed region and a medium for solubilization, diffusion, release of nutrients and growth factors, and their interactions with cells. In this work, the material and biologic properties of a novel synthetic matrix metalloproteinase (MMP) degradable hydrogel/apatite nanocomposite is investigated for its usefulness as a model matrix to mimic the gel and mineral components of the bone matrix and to fabricate aqueousbased scaffolds for bone regeneration. The gel phase is made from poly(lactide-ethylene oxidefumarate), hereafter designated as PLEOF, terpolymer in which the water content can be adjusted by changing the ratio of the hydrophobic (lactide) to hydrophilic (ethylene oxide) oligomers. The hydrogel and apatite phases are crosslinked using an MMP degradable peptide crosslinker to modulate the matrix degradation kinetics with the migration of bone marrow stromal (BMS) cells. The results demonstrate that MMP degradable scaffolds fabricated from the PLEOF hydrogel and apatite nanoparticles are biocompatible and support cell attachment and migration. INTRODUCTION There are approximately 6.2 million fractures in the United States annually that require bone graft procedures to ensure rapid skeletal repair and achieve union [1]. These include applications arising from resection of primary and metastatic tumors, bone loss after skeletal trauma, spinal arthrodesis, and trabecular voids following osteoporotic insufficiency fractures [2]. Bone matrix is a composite matrix consisting of aqueous gel and mineral phases [3]. The inorganic component, made up of apatite crystals with surface active carbonate and phosphate groups, contributes approximately 65% of the wet weight of the bone and the aqueous phase contributes about 20%. Non-collagenous water soluble glycoproteins and proteoglycans control the water content of the bone matrix to approximately 15%. The aqueous gel phase gives bone its form and contributes to its ability to resist bending, while the mineral component primarily resists compression [4]. The aqueous gel phase plays a central role in regulation of collagen fibril mineralization, modulation and control of cell division, cell migration, differentiation and maturation, maintenance of matrix integrity, growth
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