RESUMO
The mechanical property of bone tissue scaffolds is one of the most important aspects in bone tissue engineering that has remained problematic. In our previous study, we fabricated a three-dimensional scaffold from nano-hydroxyapatite/gelatin (nHA/Gel) and investigated its efficiency in promoting bone regeneration both in vitro and in vivo. In the present study, the effect of adding silicon carbide (SiC) on the mechanical and biological behaviors of the nHA/Gel/SiC and bone regeneration in vivo were determined. nHA and SiC were synthesized and characterized by the X-ray diffraction pattern and transmission electron microscope image. Layer solvent casting, freeze drying, and lamination techniques were applied to prepare these scaffolds. Then, the biocompatibility and cell adhesion behavior of the synthesized nHA/Gel/SiC scaffolds were investigated. For in vivo studies, rats were categorized into three groups: blank defect, blank scaffold, and rat bone marrow mesenchymal stem cells (rBM-MSCs)/scaffold. After 1, 4, and 12 weeks post-injury, the rats were sacrificed and the calvaria were harvested. Sections with a thickness of 5 µm thickness were prepared and stained with hematoxylin-eosin and Masson's Trichrome, and immunohistochemistry was performed. Our results showed that SiC effectively increased the mechanical properties of the nHA/Gel/SiC scaffold. No significant differences were observed in biocompatibility, cell adhesion, and cytotoxicity of the nHA/Gel/SiC in comparison with the nHA/Gel nanocomposite. Based on histological and immunohistochemical studies, both osteogenesis and collagenization were significantly higher in the rBM-MSCs/scaffold group, quantitatively and qualitatively. The present study strongly suggests the potential of SiC as an alternative strategy to improve the mechanical and biological properties of bone tissue engineering scaffolds, and shows that the pre-seeded nHA/Gel/SiC scaffold with rBM-MSCs improves osteogenesis in the engineered bone implant.
RESUMO
In this study, the effects of osteoblast-conditioning on mechanical behavior, biocompatibility, biodegradation and osteoinductive properties of a nano-hydroxyapatite/gelatin (HA/GEL) nanocomposite scaffold was investigated. The scaffold was fabricated using the layer solvent casting combined with the freeze-drying and lamination techniques. The scaffolds were conditioned by culture of osteoblasts on their surface and their elimination by a repeated freeze-thawing process. The potential of the osteoblast-conditioned HA/GEL (HA/GEL/OC) scaffold to support cell adhesion and growth and its cytotoxicity was assessed in vitro using rat mesenchymal stem cells. For in vivo studies, the HA/GEL/OC nanocomposite was implanted in the critical size bone defect created on rat calvarium and studied after 7, 30 and 90 days. The results showed that mechanical and in vitro biological properties of the scaffold were not affected by the process of conditioning. However, in vivo studies demonstrated that osteoblast-conditioning enhanced biocompatibility and osteoinductivity and of the nanocomposite scaffold. The osteoblast conditioning also accelerated collagen content during the bone healing. In the experimental group that received the HA/GEL/OC and MSCs, the newly formed bone occupied almost the entire defect (93.4 ± 3.3%) within 3 months. In conclusion, this study indicates that osteoblast-conditioning is a viable strategy for the development of bone tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2001-2010, 2016.
