Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Acta Biomater. 2023 Mar 1;158:1-11. doi: 10.1016/j.actbio.2022.12.046. Epub 2022 Dec 27.
Octacalcium phosphate (OCP) has been advocated as a precursor of bone apatite crystals. Recent studies have shown that synthetic OCP exhibits highly osteoconductive properties as a bone substitute material that stems from its ability to activate bone tissue-related cells, such as osteoblasts, osteocytes, and osteoclasts. Accumulated experimental evidence supports the proposition that the OCP-apatite phase conversion under physiological conditions increases the stimulatory capacity of OCP. The conversion of OCP progresses by hydrolysis toward Ca-deficient hydroxyapatite with Ca ion incorporation and inorganic phosphate ion release with concomitant increases in the solid Ca/P molar ratio, specific surface area, and serum protein adsorption affinity. The ionic dissolution rate during the hydrolysis reaction was controlled by introducing a high-density edge dislocation within the OCP lattice by preparing it through co-precipitation with gelatin. The enhanced dissolution intensifies the material biodegradation rate and degree of osteogenecity of OCP. Controlling the biodegradation rate relative to the dissolution acceleration may be vital for controlling the osteogenecity of OCP materials. This study investigates the effects of the ionic dissolution of OCP, focusing on the structural defects in OCP, as the enhanced metastability of the OCP phase modulates biodegradability followed by new bone formation. STATEMENT OF SIGNIFICANCE: Octacalcium phosphate (OCP) is recognized as a highly osteoconductive material that is biodegradable by osteoclastic resorption, followed by new bone formation by osteoblasts. However, if the degradation rate of OCP is increased by maintaining the original osteoconductivity or acquiring a bioactivity better than its current properties, then early replacement with new bone can be expected. Although cell introduction or growth factor addition by scaffold materials is the standard method for tissue engineering, material activity can be augmented by introducing dislocations into the lattice of the OCP. This review article summarizes the effects of introducing structural defects on activating OCP, which was obtained by co-precipitation with gelatin, as a bone substitute material and the mechanism of improved bone replacement performance.
八钙磷酸盐（OCP）被认为是骨磷灰石晶体的前体。最近的研究表明，合成的 OCP 作为一种骨替代材料具有高度的骨诱导特性，这源于它激活骨组织相关细胞（如成骨细胞、骨细胞和破骨细胞）的能力。大量的实验证据支持这样的观点，即在生理条件下 OCP-磷灰石相转化会增加 OCP 的刺激能力。OCP 的转化通过水解进行，朝着具有 Ca 离子掺入和无机磷酸离子释放的 Ca 缺乏羟基磷灰石进行，同时固体 Ca/P 摩尔比、比表面积和血清蛋白吸附亲和力增加。水解反应期间的离子溶解速率通过在 OCP 晶格中通过与明胶共沉淀制备来引入高密度边缘位错来控制。增强的溶解会加剧 OCP 的材料生物降解速率和成骨性。控制相对于溶解加速的生物降解速率对于控制 OCP 材料的成骨性可能至关重要。本研究探讨了 OCP 的离子溶解的影响，重点研究了 OCP 中的结构缺陷，因为 OCP 相的增强亚稳性调节生物降解性，随后形成新骨。研究意义：八钙磷酸盐（OCP）被认为是一种高度骨诱导性材料，可通过破骨细胞吸收进行生物降解，随后由成骨细胞形成新骨。然而，如果通过维持原始骨诱导性或获得优于其现有特性的生物活性来增加 OCP 的降解速率，则可以预期早期用新骨替代。尽管通过支架材料引入细胞或生长因子是组织工程的标准方法，但通过在 OCP 晶格中引入位错可以增强材料的活性。这篇综述文章总结了引入结构缺陷对激活 OCP 的影响，OCP 是通过与明胶共沉淀获得的，作为一种骨替代材料以及改善骨替代性能的机制。
