Biocompatibility, Bioactivity and Mechanical Properties of Portland Cement and Portland Cement-Metakaolin Blends for Bon
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1094-DD09-04
Biocompatibility, Bioactivity and Mechanical Properties of Portland Cement and Portland Cement-Metakaolin Blends for Bone Tissue Engineering Applications Daniel Gallego1, Natalia Higuita1, Felipe Garcia2, Olga M. Posada2, Luis E. Lopez2, Alan S. Litsky1, and Derek J. Hansford1 1 Biomedical Enginering Department, The Ohio State University, 1080 Carmack Road (Bevis Hall, Suite 270), Columbus, OH, 43210 2 Grupo de Investigacion en Ingenieria Biomedica EIA-CES (GIBEC), Envigado, Colombia ABSTRACT We studied the potential applications of Portland cement and Portland cementMetakaolin blends as scaffolding materials for load bearing bone tissue engineering. Cementitious pastes were prepared by mixing Portland cement and Metakaolin at different ratios (100:0, 85:15), and hydrated under a concentrated CO2 atmosphere (carbonated pastes). Pastes fabricated similarly, but hydrated under normal atmospheric conditions were used for comparison (non-carbonated pastes). Compressive tests were run to evaluate the mechanical properties of the pastes. The bioactivity of the samples was tested in a simulated body fluid (SBF) solution for 1 and 4 days. Sample morphology and chemistry were characterized via scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The cytocompatibility was studied using human osteosarcoma (HOS) cell cultures and the direct contact assay. Mechanical characterization did not show significant differences in the compressive strength of the blends compared to pure cement controls. The bioactivity test revealed that the pastes induced surface precipitation of calcium phosphate (CaP) when exposed to the SBF solution (as confirmed by SEM and EDS). Non-carbonated pastes induced early CaP precipitation. Cytocompatibility experiments showed that the carbonated blends allowed adequate cell growth. Non-carbonated blends presented a highly cytotoxic behavior. The introduction of Metakaolin did not affect the cytocompatibility of the samples. These results show that Portland cement and Portland cement-Metakaolin blends could present suitable characteristics for applications as scaffolding materials in load bearing bone tissue engineering. INTRODUCTION Bone substitutes are required to repair osseous defects caused by a number of factors, such as traumas, degenerative diseases, cancer, and others. Bone autografts and allografts have traditionally been used to treat these problems; however, their implementation still presents several disadvantages, including the lack of donors, potential of immune rejection, possible pathogen transmission, and high donor site morbidity among others [1]. Bone tissue engineering (BTE) aims to restore lost or damaged bone tissue by combining cells, scaffolds and growth factors and thereby overcome the drawbacks presented by conventional auto and allografting procedures [2]. Previous research in the development of scaffolding materials for BTE has allowed us to identify a set of minimum required characteristics to achieve satisfactory bone tissue
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