Preparation and In Vitro Characterization of Polycaprolactone and Demineralized Bone Matrix Scaffolds
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Preparation and In Vitro Characterization of Polycaprolactone and Demineralized Bone Matrix Scaffolds Titilayo Moloye1, Christopher Batich1,2 1 Biomedical Engineering Department, University of Florida, Gainesville, FL 32611 2 Materials Science and Engineering Department, University of Florida, Gainesville, FL 32611 ABSTRACT Cylindrical porous polycaprolactone (PCL) scaffolds containing 25, 35, and 50 wt% demineralized bone matrix (DBM) were fabricated using a salt-leaching method for application in bone engineering. In the present work, PCL-DBM scaffolds were monitored for calcium and phosphorus deposition in both deionized (DI) water and simulated body fluid (SBF) for time periods of 5, 10, 15, and 20 days at 37°C under constant rotation. An in vitro assessment of the bioactivity of synthetic materials using SBF under physiological conditions can be used as a barometer of scaffold behavior in vivo. DBM, an osteoinductive material, was used to gauge if there was a correlation between the concentration of DBM within a scaffold and the apatite formation on its surface. Biochemical assays, alizarin red S staining, and scanning electron microscopy (SEM) with elemental analysis of calcium and phosphorus were consistent in that they confirmed that PCL scaffolds containing 35 wt% DBM in SBF at 14 days post-immersion showed signs of early apatite formation. INTRODUCTION Osteoconduction and osteoinduction Bone defects and fractures are quite common in both adolescents and older adults. Strenuous physical activities, calcium deficiency, bone cancer, and osteoporosis (especially in the elderly) are the usual causes of bone defects and fractures. Moreover, ~30% of all battlefield trauma cases reported in the conflicts in Iraq and Afghanistan involved bone fractures, typically owing to high-energy events, such as blasts or gunshots [1]. While some smaller and more contained defects and fractures may heal on their own, many require the use of bone substitutes to achieve healing. Many of these substitutes demonstrate the phenomenon known as osteoconductivity, a property that allows bone to grow on its surface. However, very few of these substitutes contribute to the recruitment and proliferation of immature cells to the defect or fracture site. This property is known as osteoinductivity [2]. In the present work, a novel osteconductive and osteoinductive polymer scaffold designed for contained bone defects resulting from bone traumatic injury is reported. Predicting the in vivo bone bioactivity of materials Synthetic materials implanted in vivo in a bone defect often lead to encapsulation by fibrous connective tissue. This encapsulation isolates the material from native bone, thereby rendering the material ineffective as a bone defect substitute [3]. In order for a material to bond directly to bone when implanted in vivo, without encapsulation by fibrous tissue, bonelike apatite needs to form on the bone surface. It is known that the in vivo bone bioactivity of materials can be predicted in vitro by immersing synthetic materials in
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