Properties Of Octacalcium Phosphate Research Articles

Effect of calcium phosphate phases affecting the crosstalk between osteoblasts and osteoclasts in vitro.

Previous studies have reported that octacalcium phosphate (OCP) enhances osteoblast differentiation and osteoclast formation during the hydrolysis process to hydroxyapatite (HA). However, the crystal phases that affect the crosstalk between osteoclasts and osteoblasts are unknown, which should determine the bone substitute material's property of OCP. The present study was designed to investigate whether the chemical composition and crystal structure of calcium phosphates affect osteoclast formation and the osteoclast-osteoblast crosstalk. Biodegradable β-tricalcium phosphate (β-TCP) was used as the control material. Osteoclasts were cultured on HA/OCP or HA/TCP disks and their cellular responses were assessed. Both OCP and β-TCP had a similar ability to create multinucleated osteoclasts. However, OCP promoted the expression of complement component 3a (C3a), a positive coupling factor, in osteoclasts, whereas β-TCP enhanced that of EphrinB2 (EfnB2) and collagen triple helix repeat containing 1 (Cthrc1). During osteoclast culture, phosphate ions were released from the crystals, and OCP-HA conversion was advanced in HA/OCP mixtures and OCP. X-ray diffraction analysis revealed no remarkable changes in the crystal structures of HA/TCP mixtures and β-TCP before and after osteoclast culture. These results indicate that the distinct chemical environment induced by the calcium phosphate phases affects the crosstalk between osteoclasts and osteoblasts. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1001-1013, 2019.

Unique Dicarboxylate Ion Incorporation in Octacalcium Phosphate

Various dicarboxylate ions can be incorporated into the crystal structure of octacalcium phosphate (OCP). This unique property can be applied to develop functional bone substitute materials. However, there are many unclear points regarding the chemistry of OCP with incorporated dicarboxylate ions. In this review, we discuss the following three topics regarding the fundamental properties of OCP with incorporated dicarboxylate ions: the incorporation of two types of dicarboxylate ions into the OCP interlayer, the precise control of the interplanar spacing for OCP with dicarboxylate ions having a side chain, and the chirality recognition of guest molecules during OCP incorporation phenomena.

Effect of Octacalcium Phosphate-Based Bone Substitute Materials on Oriented Bone Regeneration

The characteristics and the biological responses of octacalcium phosphate (OCP) crystals, obtained in the presence of natural polymers, were summarized based on our studies reported. OCP obtained with collagen molecules in the solution had a plate-like morphology while OCP obtained with gelatin molecules in the solution exhibited elongated morphology toward long axis of the crystals. Oriented bone matrix formation was observed by the OCP inclusion in gelatin sponge in a critical-sized rat calvaria defect within the implantation periods around 8 weeks. It seems likely that specific crystal property of OCP obtained in distinct preparation conditions may affect bone tissue response probably through the modulation of OCP crystal characteristics.

Osteoinductive ceramic materials for bone tissue restoration: Octacalcium phosphate (review)

Data are presented on the structure and properties of octacalcium phosphate, which exhibits osteoinductivity, i.e., the ability to stimulate bone tissue formation in living organisms. Some features of its chemical synthesis by precipitation from aqueous solutions or by hydrolysis of other calcium phosphates are described. The results of studies of the transformations that take place in octacalcium phosphate in simulated body fluid, as well as data of biological tests on animals in vivo, are given.

Bone Regenerative Property of Octacalcium Phosphate in Mouse Critical Sized Calvarial Defects

Bone regeneration by calcium phosphates has been known to be intricately dependent on material properties or implanted milieu of host animals, such as site and species. Critical sized calvarial defects of mouse were recently used as the model for investigating bone regeneration ability and the mechanisms. The purpose of the present study is to investigate whether the critical sized mouse calvarial defects can be utilized to examine bone regeneration with synthetic octacalcium phosphate (OCP). OCP , prepared by wet synthesis methods, was sieved 0.3 ~ 0.5 mm in diameter and used for the animal experiment. At 14 days after surgery, histological examination showed that implantation of OCP grafted defects significantly enhanced bone formation compared with the control defect. OCP tended to convert to hydroxyapatite with time. The tartrate-resistant acid phosphatase (TRAP) positive osteoclastic cells were observed around the OCP particles. The results suggest that the mouse critical sized calvarial bone defects are useful model to investigate the bone formation by the OCP implantation.