Bone Regenerative Engineering Laboratory, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.
Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
J Biomed Mater Res B Appl Biomater. 2020 Oct;108(7):2827-2834. doi: 10.1002/jbm.b.34613. Epub 2020 Apr 2.
Even though conventionally prepared octacalcium phosphate and collagen composite (OCP/Col) has exhibited excellent bone regeneration and has recently been commercialized for treating bone defects, reproducible appositional bone formation with OCP/Col has never been achieved. The present study investigated whether appositional bone formation could be achieved by altering the density of OCP/Col and applying liquid nitrogen during the preparation of OCP/Col. The prepared OCP/Col disks had eight variations and were divided into categories according to four different type of densities (1.0, 1.3, 1.7, and 2.0) of OCP/Col and two different pre-freezing conditions of gas phase (G group: -80°C) and liquid phase (L group: -196°C). These disks were implanted into subperiosteal pockets in rodent calvaria, five samples per each eight variations. Radiomorphometric analysis was conducted at 4 and 12 weeks after implantation, and histological analysis was conducted at 12 weeks after implantation. OCP/Col samples in the L group tended to retain their height and shape and had enhanced appositional bone formation, whereas OCP/Col samples in the G group tended to lose their height and shape and had limited appositional bone formation. The appositional bone formation increased along with growing density of OCP/Col, and L2.0 demonstrated higher appositional bone formation than other samples. These results suggest that the pre-freezing conditions and densities of OCP/Col affect the appositional bone formation.
尽管传统制备的八钙磷灰石/胶原复合材料（OCP/Col）已表现出优异的骨再生能力，并已最近商业化用于治疗骨缺损，但从未实现过 OCP/Col 的可重复附着性骨形成。本研究探讨了通过改变 OCP/Col 的密度并在制备 OCP/Col 过程中施加液氮是否可以实现附着性骨形成。制备的 OCP/Col 圆盘有八种变化，并根据 OCP/Col 的四种不同密度（1.0、1.3、1.7 和 2.0）和两种不同的预冷冻条件（气相（G 组：-80°C）和液相（L 组：-196°C）进行分类。这些圆盘被植入啮齿动物颅骨的骨膜下袋中，每种变化有五个样本。在植入后 4 和 12 周进行放射形态计量学分析，并在植入后 12 周进行组织学分析。L 组的 OCP/Col 样本倾向于保持其高度和形状，并增强附着性骨形成，而 G 组的 OCP/Col 样本倾向于失去高度和形状，并限制附着性骨形成。随着 OCP/Col 密度的增加，附着性骨形成增加，而 L2.0 的附着性骨形成高于其他样本。这些结果表明，OCP/Col 的预冷冻条件和密度会影响附着性骨形成。
