Osteogenic potential of biosilica on human osteoblast-like (SaOS-2) cells.
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.
Wiens
Matthias
M
Institute for Physiological Chemistry, Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55128, Mainz, Germany.
Wang
Xiaohong
X
Schlossmacher
Ute
U
Lieberwirth
Ingo
I
Glasser
Gunnar
G
Ushijima
Hiroshi
H
Schröder
Heinz C
HC
Müller
Werner E G
WE
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*
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D012822:Silicon Dioxide; D017886:Durapatite