title: Osteogenic potential of biosilica on human osteoblast-like (SaOS-2) cells.
abstract: Biosilica is a natural polymer, synthesized by the poriferan enzyme silicatein from monomeric silicate substrates. Biosilica stimulates mineralizing activity and gene expression of SaOS-2 cells. To study its effect on the formation of hydroxyapatite (HA), SaOS-2 cells were grown on different silicatein/biosilica-modified substrates (bone slices, Ca-P-coated coverslips, glass coverslips). Growth on these substrates induced the formation of HA nodules, organized in longitudinal arrays or spherical spots. Nodules of sizes above 1 μm were composed of irregularly arranged HA prism-like nanorods, formed by aggregates of three to eight SaOS-2 cells. Moreover, growth on silicatein/biosilica-modified substrates elicited increased [(3)H]dT incorporation into DNA, indicative of enhanced cell proliferation. Consequently, an in vitro-based bioassay was established to determine the ratio between [(3)H]dT incorporation and HA formation. This ratio was significantly higher for cells that grew on silicatein/biosilica-modified substrates than for cells on Ca-P-coated coverslips or plain glass slips. Hence, we propose that this ratio of in vitro-determined parameters reflects the osteogenic effect of different substrates on bone-forming cells. Finally, qRT-PCR analyses demonstrated that growth of SaOS-2 cells on a silicatein/biosilica matrix upregulated BMP2 (bone morphogenetic protein 2, inducer of bone formation) expression. In contrast, TRAP (tartrate-resistant acid phosphatase, modulator of bone resorption) expression remained unaffected. We conclude that biosilica shows pronounced osteogenicity in vitro, qualifying this material for studies of bone replacement also in vivo.
authors: Institute for Physiological Chemistry, Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany.
authors: Matthias
authors: M
authors: Wiens
authors: Xiaohong
authors: X
authors: Wang
authors: Ute
authors: U
authors: Schlossmacher
authors: Ingo
authors: I
authors: Lieberwirth
authors: Gunnar
authors: G
authors: Glasser
authors: Hiroshi
authors: H
authors: Ushijima
authors: Heinz C
authors: HC
authors: Schröder
authors: Werner E G
authors: WE
authors: Müller
mesh_terms: D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D017886:Durapatite / Q000378:metabolism*; D006801:Humans; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010012:Osteogenesis; D012822:Silicon Dioxide / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D012822:Silicon Dioxide; D017886:Durapatite