Effect of partial hydrolysis of octacalcium phosphate on its osteoconductive characteristics

• Published in: Biomaterials 2009-02, Vol.30 (6), p.1005-1014
• Main Authors: Miyatake, Naohisa, Kishimoto, Koshi N, Anada, Takahisa, Imaizumi, Hideki, Itoi, Eiji, Suzuki, Osamu
• Format: Article
• Language: English
• Subjects: Acid Phosphatase - metabolism; Advanced Basic Science; Animals; Biodegradation; Bone marrow; Bone Regeneration - drug effects; Calcium Phosphates - metabolism; Calcium Phosphates - pharmacology; Crystallization; Cytokines - genetics; Cytokines - metabolism; Dentistry; Gene Expression Profiling; Gene Expression Regulation - drug effects; Hydrolysis - drug effects; Immunohistochemistry; Implants, Experimental; Inflammation Mediators - metabolism; Isoenzymes - metabolism; Male; Octacalcium phosphate; Osteconduction; Osteocalcin - metabolism; Osteoclasts - drug effects; Osteoclasts - metabolism; Osteogenesis - drug effects; Osteopontin - metabolism; Partial hydrolysis; Rats; Rats, Sprague-Dawley; RNA, Messenger - genetics; RNA, Messenger - metabolism; Surface Properties - drug effects; Tartrate-Resistant Acid Phosphatase; Tibia - abnormalities; Tibia - drug effects; Tibia - enzymology; Tibia - pathology; Time Factors
• ISSN: 0142-9612; 1878-5905
• DOI: 10.1016/j.biomaterials.2008.10.058

Abstract The present study was designed to investigate whether the stoichiometry of octacalcium phosphate OCP affects its osteoconductive and immune response characteristics in rat bone marrow. Those characteristics of synthetic, well-grown OCP but with a non-stoichiometric composition were compared with those of a slightly hydrolyzed OCP (low crystalline OCP: LC-OCP), the fully hydrolyzed apatitic product of OCP or biodegradable β-tricalcium phosphate (β-TCP) ceramic, by their implantation in rat tibia for 56 days. The physicochemical aspect of implants and biological responses were analyzed by X-ray diffraction, histomorphometry, immunohistochemistry and expression of mRNA around the implants. The remarkable findings were that: (1) the highest bone formation rate was obtained for β-TCP whereas the lowest for LC-OCP at Day 14; (2) the rates were reversed and reached the highest for LC-OCP until Day 56; (3) the early expression of ostoeoclast markers TRAP and cathepsin-K was suppressed with LC-OCP; (4) the expression of inflammatory markers IL-β1 and TNF-α was suppressed with LC-OCP. The results confirmed that the partially hydrolyzed OCP with Ca/P molar ratio 1.37 (LC-OCP) enhances bone formation most, suppressing early osteoclast activity and reducing inflammation.