Biosilica The osteogenic bioinorganic polymer

The formation of the skeletal system from the earliest metazoans, the sponges (phylum Porifera) (Muller et al., 2(X)9a,b) to the crown taxa, the mammalians (Matsuo and Irie, 2008) and the insects (Moussian, 2010), is dominated by a tuned communication between cells controlling anabolic processes and cells executing catabolic reactions. Basically, two kinds of inorganic scaffold materials had been applied in the metazoan kingdom to form skeletons calcium (calcium-based skeletal systems) and—only found in siliceous sponges—silica (silica-based skeletons). 

Previous experimental evidence shows that silicate/silicon is an essential trace element in vertebrate nutrition (Carlisle, 1972 Schwarz and Milne, 1972  

In addition, the differentiation of osteoblasts is induced and accelerated by BMP-2 (bone morphogenetic protein 2). It is assumed that in turn the osteoblasts acquire the potential to differentiate to osteocytes and to lining cells. Furthermore, OPG counteracts various effects of RANKL, a cytokine that induces pre-osteoclast maturation and osteoclast activation. Finally, it could be identified that the osteoblasts release a factor, the osteoblasts-derived inhibitory factor, which strongly inhibits the proliferation of osteoclasts the nature of this factor is not yet known. 

---