Expression of Non-collagenous Proteins

Osteocalcin is exclusively secreted by osteoblasts and thought to play a role in body s metabolic regulation and bone-building ability (Lee et al., 2007). It is also implicated in bone mineralisation and calcium ion homeostasis. As osteocalcin 

Osteopontin (formerly known as bone sialoprotein I) binds tightly to hydroxyapatite in bone and thus forms an integral part of the mineralised matrix. It has been postulated to be a ligand for the vitronectin receptor, and this suggests a possible role of osteopontin in osteoclast attachment and function (Merry et al., 1993). Hence, it functions as a potent marker of ossification and consequently its expression serves to quantify the degree of mineralisation of bone tissue in contact with bioceramic materials including coatings. 

Osteonectin is a bone glycoprotein that binds calcium. It is secreted by osteoblasts during bone formation, initiating mineralisation and promoting CDHAp crystal formation. High levels of immunodetectable osteonectin are 

The search for a protein-based promoter of hydroxyapatite crystal nucle-ation has been a focus for the isolation and characterisation of the major non-collagenous proteins in bone. Of the proteins characterised to date, BSP II has emerged as the only bona fide candidate for nucleation. BSP is a highly glycosylated and sulfated phosphoprotein found almost exclusively in mineralised connective tissues and has been suggested to constitute approximately 8% of all non-collagenous proteins found in bone. 

Earlier work by Hulbert, Morrison and Klawitter (1972) confirmed that calcium zirconate ceramics implanted intramuscularly in rabbits promoted the formation of a 100-200 pm thick pseudo membrane that within 6-9 months gradually den-sified without the presence of inflammatory cells thus suggesting a high degree of biotolerance. Recent work by Liu et al. (2006) showed that nanostructured Zr02 films formed by cathodic arc deposition on silicon surfaces promote the formation of apatite when incubated in SBF. On the apatite, growth and proliferation of 

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