In vitro Evaluation of Macrophage Adhesion and Proliferation on Alumina
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0950-D15-05
In vitro Evaluation of Macrophage Adhesion and Proliferation on Alumina Peishan Liu-Snyder and Thomas J. Webster Division of Engineering, Brown University, 184 Hope Street, Providence, RI, 02912
ABSTRACT Extensive interactions of inflammatory cells (such as macrophages) with biomaterials at the host-implant interface are often blamed for failure of implanted biomedical devices [1]. While previous studies have shown increased in vitro and in vivo bone cell (osteoblast) responses on nanophase ceramics [2], few (if any) studies have been conducted to elucidate inflammatory cell responses on such novel materials. In this study, we reported that macrophage adhesion and proliferation on nanophase (97.7 nm grain size) alumina (Al2O3) was significantly less than conventional (187.4 nm grain size) alumina, respectively, after 4, 12, 24 h. The present study provides evidence of the ability of nanophase alumina to down-regulate macrophage adhesion and proliferation, which is imperative for the future consideration of nanophase materials for orthopedic and dental applications. INTRODUCTION Alumina (Al2O3) has been used in orthopedic and dental implants because it, like other ceramics, possesses desirable mechanical properties and the oxide surface makes alumina and other ceramics chemically inert and resistant to physical and chemical changes inside the body [3]. However, orthopedic implants made of traditional ceramics often fail during long term applications. This is often due to poor initial bonding of implants to the juxtaposed bone. Insufficient bonding can be caused by a lack of osseointegration, osteolysis and the formation of soft fibrous tissue at the bone-implant interface [4]. There are several types of cells involved in these critical processes following implantation. For example, osteoblasts are the bone forming cells. They produce extracellular matrix proteins, mainly type I collagen, and they deposit calcium in the extracellular matrix [5]. Fibroblasts have been involved in the formation of soft connective tissue which exhibits much weaker mechanical properties than bone. The replacement of bone by connective tissue can not support the strong bonding between bone and the implant. Macrophages form the first line of defense against bacteria, viruses and foreign materials (such as those that have been used for orthopedic applications). Because orthopedic surgery causes trauma to the local tissue and introduces infection to the surgery site, macrophages migrate to the bone-implant interface and become activated upon implantation. Activated macrophages produce proinflammatory cytokines, chemokines, matrix proteins and other substances, which not only can cause osteolysis but also can stimulate the proliferation of fibroblasts [4]. Many approaches have been taken to extend the life of implant devices in the body so that patients who received them do not need revision surgeries. Among them, nanotechnology has been applied to improve the biocompatibility of orthopedic implant materials. It has been shown th
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