Department of Orthopedic Surgery, the Second Affiliated Hospital, School of Medicine of Zhejiang University, Hangzhou 310009, China.
Bio-nanomaterials and Regenerative Medicine Research Division, Zhejiang-California International Nanosystem Institute, Zhejiang University, Hangzhou 310058, China.
Mater Sci Eng C Mater Biol Appl. 2019 Jul;100:433-444. doi: 10.1016/j.msec.2019.03.026. Epub 2019 Mar 9.
Bioactive stimulation and spatiotemporal evolution of porous scaffolds with time are crucial for bone regeneration rate in bone repair process. Granule-type bioceramic scaffolds have attracted significant interest in biomedical applications in recent years. However, the major limitation of such porous architecture is that the low initial porosity is disadvantageous for enhancing new bone tissue ingrowth. Here we reported that the yolk-shell-structured biphasic bioceramic granules with adjustable shell microstructures were favorable for controllable ion release in vitro, superior to the granules with the conventional homogenous hybrid structures. Also, we illustrated a significant difference in biodegradation of the granules in vivo, and especially the porous-shell granules exhibited appreciable new bone tissue ingrowth with time. The underlying fundamental mechanisms governing the new bone tissue ingrowth behavior of the yolk-shell granule scaffolds were elucidated based on microCT analyses and histological observation. It was underscored that during biodegradation in vivo, the highly bioactive ions in yolk layer were continuously released due to the porous structures of the sparingly dissolvable shell layer, thereby resulting in hollow shell and rapid new bone tissue ingrowth. Hence, these results demonstrate that the slight tailoring in microstructure and component distribution of biphasic composites is beneficial for adjusting the bone regeneration, and may help us to precisely control bone repair efficiency for a variety of clinical conditions.
生物活性刺激和多孔支架的时空演变随时间的推移对于骨修复过程中的骨再生速率至关重要。近年来，颗粒型生物陶瓷支架在生物医学应用中引起了极大的关注。然而，这种多孔结构的主要限制是低初始孔隙率不利于增强新的骨组织向内生长。在这里，我们报道了具有可调节壳微结构的蛋黄壳结构的双相生物陶瓷颗粒有利于体外可控的离子释放，优于具有传统均匀混合结构的颗粒。此外，我们还说明了体内颗粒的生物降解存在显著差异，特别是多孔壳颗粒随时间表现出明显的新骨组织向内生长。基于 microCT 分析和组织学观察，阐明了蛋黄壳颗粒支架新骨组织向内生长行为的基本机制。强调指出，在体内生物降解过程中，由于疏水性壳层的多孔结构，蛋黄层中的高生物活性离子不断释放，从而导致空心壳和快速的新骨组织向内生长。因此，这些结果表明，双相复合材料的微观结构和成分分布的细微调整有利于调节骨再生，并可能有助于我们精确控制各种临床情况下的骨修复效率。
