Iowa Institute for Oral Health Research, University of Iowa College of Dentistry, Iowa City, Iowa, United States; Department of Prosthodontics, University of Iowa College of Dentistry, Iowa City, Iowa, United States.
Iowa Institute for Oral Health Research, University of Iowa College of Dentistry, Iowa City, Iowa, United States.
Acta Biomater. 2018 Jul 15;75:463-471. doi: 10.1016/j.actbio.2018.05.047. Epub 2018 May 30.
There is increasing interest in biodegradable ceramic scaffolds for bone tissue engineering capable of in situ delivery of ionic species favoring bone formation. Strontium has been shown to be osteogenic, but strontium-containing drugs such as strontium ranelate, used in Europe for the treatment of osteoporosis, are now restricted due to clinical evidence of systemic effects. By doping fluorapatite-based glasses with strontium, we developed ceramic scaffolds with fully interconnected macroporosity and cell size similar to that of cancellous bone, that are also capable of releasing strontium. The crystallization behavior, investigated by XRD and SEM, revealed the formation of akermanite and fluorapatite at the surface of strontium-free glass-ceramic scaffolds, and strontium-substituted fluorapatite at the surface of the strontium-doped scaffolds. At 8 weeks after implantation in a rat calvarial critical size defect, scaffolds doped with the highest amount of strontium led to the highest mineral apposition rate. A significantly higher amount of newly-formed bone was found with the strontium-free glass-ceramic scaffold, and possibly linked to the presence of akermanite at the scaffold surface. We demonstrate by energy dispersive XRF analyses of skull sections that strontium was present in newly formed bone with the strontium-doped scaffolds, while a significant amount of fluorine was incorporated in newly formed bone, regardless of composition or crystallization state.
The present work demonstrates the in vivo action of strontium-containing glass-ceramic scaffolds. These bone graft substitutes are targeted at non load-bearing bone defects. Results show that strontium is successfully incorporated in newly formed bone. This is associated with a significantly higher Mineral Apposition Rate. The benefits of in situ release of strontium are demonstrated. The broader scientific impact of this works builds on the concept of resorbable ceramic scaffolds as reservoirs of ionic species capable of enhancing bone regeneration.
人们对可生物降解的陶瓷支架越来越感兴趣，这些支架可用于骨组织工程，能够原位输送有利于成骨的离子物质。锶已被证明具有成骨性，但欧洲用于治疗骨质疏松症的含锶药物（如雷奈酸锶）由于有系统作用的临床证据而受到限制。通过在氟磷灰石基玻璃中掺杂锶，我们开发出了具有完全连通的大孔和与松质骨相似的细胞大小的陶瓷支架，这些支架还能够释放锶。通过 XRD 和 SEM 研究发现，在无锶玻璃陶瓷支架的表面形成了硅灰石和氟磷灰石，而在锶掺杂支架的表面形成了锶取代的氟磷灰石。在大鼠颅骨临界尺寸缺损中植入 8 周后，掺杂最高量锶的支架导致了最高的矿化附着率。无锶玻璃陶瓷支架的新骨形成量明显更高，可能与支架表面存在硅灰石有关。我们通过颅骨切片的能量色散 XRF 分析证明，锶存在于锶掺杂支架的新形成骨中，而无论组成或结晶状态如何，氟都大量掺入新形成骨中。
本工作证明了含锶玻璃陶瓷支架的体内作用。这些骨移植物替代品针对非承重骨缺损。结果表明，锶成功地掺入了新形成的骨中。这与更高的矿化附着率有关。体内释放锶的益处得到了证明。这项工作的更广泛的科学影响建立在可吸收陶瓷支架作为能够增强骨再生的离子物质储存库的概念之上。
