Abstract
Various bone grafting materials are used for bone augmentation procedures in the field of oral-maxillofacial surgery. Knowledge of biomaterial characteristics is crucial in order to choose the appropriate materials for each clinical case. The purpose of the present study was to investigate not only the conventional method of comparison of osteogenic potential of different bone grafting materials, but also evaluate the macrophage behavior and the potential as carriers of growth factors in vitro.
Cell attachment/proliferation on bone grafting materials and the gene expressions of cell differentiation markers were investigated in the human leukemia monocytic cell line THP-1-derived macrophages and mouse stromal ST-2 cells, when cultured on the three different grafting materials of 1) demineralized freeze-dried bone allografts (DFDBA)(DBX®, Synthes Inc. USA), 2) deproteinized bovine bone mineral (DBBM)(Bio-Oss®, Geistlich Pharma AG, Switzerland), and 3) biphasic calcium phosphate (BCP)(Maxresorb® granules, Botiss AG, Germany). Furthermore, bone morphogenetic protein-2 (BMP-2) adsorption, release kinetics, and osteoblastic activities of BMP-2-loaded materials were evaluated.
Higher cell attachment/proliferation potentials in both THP-1-derived macrophages and ST-2 cells were observed when cultured on BCP. Interestingly, DFDBA showed high TNF-α expression with a strong tendency toward M1 phenotypes, whereas BCP showed high IL-10 expression in macrophages and was polarized toward M2 phenotypes. Furthermore, DFDBA significantly increased mRNA levels of bone sialoprotein (BSP) when compared to the other materials in ST-2 cells. DBBM adsorbed a higher amount of BMP-2 when compared with the other materials while the DFDBA released BMP-2 faster. DFDBA showed higher osteopromotive potential including higher mRNA levels of ALP and BSP when used in combination with BMP-2, compared to BMP-2 alone.
From this limited study, BCP showed superior cytocompatibility. Nevertheless, DFDBA might be a good option when focusing on higher osteopromotive potential, and for use as a BMP-2 carrier.
