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Strontium-releasing fluorapatite glass-ceramic scaffolds: Structural characterization and in vivo performance
Journal article   Open access   Peer reviewed

Strontium-releasing fluorapatite glass-ceramic scaffolds: Structural characterization and in vivo performance

Isabelle Denry, Ourania-Menti Goudouri, Douglas C Fredericks, Adil Akkouch, Michael R Acevedo and Julie A Holloway
Acta biomaterialia, Vol.75, pp.463-471
07/15/2018
DOI: 10.1016/j.actbio.2018.05.047
PMCID: PMC6119524
PMID: 29859366
url
https://doi.org/10.1016/j.actbio.2018.05.047View
Published (Version of record) Open Access

Abstract

[Display omitted] 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.
Strontium Akermanite Scaffold Osteogenesis Fluorapatite

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