Santana-Melo Gabriela F, Rodrigues Bruno V M, da Silva Edmundo, Ricci Ritchelli, Marciano Fernanda R, Webster Thomas J, Vasconcellos Luana M R, Lobo Anderson O
Department of Bioscience and Oral Diagnosis, Institute of Science and Technology, Sao Paulo State University, Sao Jose dos Campos, Sao Paulo, Brazil.
Laboratory of Biomedical Nanotechnology, Universidade Brasil, Itaquera, Sao Paulo, Brazil.
Colloids Surf B Biointerfaces. 2017 Jul 1;155:544-552. doi: 10.1016/j.colsurfb.2017.04.053. Epub 2017 Apr 27.
Combining polyester scaffolds with synthetic nanohydroxyapatite (nHAp), which is bioactive and osteoconductive, is a plausible strategy to improve bone regeneration. Here, we propose the combination of PBAT [poly(butylene-adipate-co-terephthalate)] and synthetic nHAp (at 3 and 5wt%). PBAT is a relatively a new polymer with low crystallinity and attractive biodegradability and mechanical properties for orthopedic applications, however, with a still underexplored potential for in vivo applications. Then, we performed a careful biological in vitro and in vivo set of experiments to evaluate the influence of PBAT containing two different nHAp loads. For in vitro assays, osteoblast-like MG63 cells were used and the bioactivity and gene expression related to osteogenesis were evaluated by qRT-PCR. For in vivo experiments, twenty-four male rats were used and a tibial defect model was applied to insert the scaffolds. Micro-computed tomography (Micro-CT) and histological analysis were used to assess e bone neoformation after 6 weeks of implantation. Three point flexural tests measured the mechanical properties of the neoformed bone. All scaffolds showed promising in vitro properties, since they were not cytotoxic against MG-63 cells and promoted high cell proliferation and formation of mineralized nodules. From a mechanistic point-of-view, nHAp loading increased hydrophilicity, which in turn allowed for a better adsorption of proteins and consequent changes in the phenotypic expression of osteoblasts. nHAp induced better cellular responses on/in the scaffolds, which was mainly attributed to its osteoconductive and osteoinductive properties. Micro-CT images showed that nHAp at 3% and 5wt% led to more effective bone formation, presenting the highest bone volume after 6 weeks of implantation. Considering the three point flexural tests, 5wt% of nHAp positively influenced the flexural mode of the neoformed bone, but the stiffiness was similar between the 3% and 5wt% groups. In summary, this investigation demonstrated great potential for the application of these novel scaffolds towards bone regeneration and, thus, should be further studied.
将具有生物活性和骨传导性的合成纳米羟基磷灰石（nHAp）与聚酯支架相结合，是改善骨再生的一种可行策略。在此，我们提出将聚（丁二酸丁二醇酯-共-对苯二甲酸酯）（PBAT）与合成nHAp（3wt%和5wt%）相结合。PBAT是一种相对较新的聚合物，结晶度低，具有吸引人的生物降解性和适合骨科应用的机械性能，然而，其体内应用潜力仍未得到充分探索。然后，我们进行了一系列仔细的体外和体内生物学实验，以评估含有两种不同nHAp负载量的PBAT的影响。对于体外试验，使用了成骨样MG63细胞，并通过qRT-PCR评估了与骨生成相关的生物活性和基因表达。对于体内实验，使用了24只雄性大鼠，并应用胫骨缺损模型植入支架。在植入6周后，使用微计算机断层扫描（Micro-CT）和组织学分析来评估新骨形成情况。三点弯曲试验测量了新形成骨的机械性能。所有支架均显示出有前景的体外性能，因为它们对MG-63细胞无细胞毒性，并促进了高细胞增殖和矿化结节的形成。从机制角度来看，nHAp负载增加了亲水性，这反过来又使得蛋白质能够更好地吸附，并导致成骨细胞表型表达发生变化。nHAp在支架上/内诱导了更好的细胞反应，这主要归因于其骨传导性和骨诱导性。Micro-CT图像显示，3wt%和5wt%的nHAp导致了更有效的骨形成，在植入6周后呈现出最高的骨体积。考虑到三点弯曲试验，5wt%的nHAp对新形成骨的弯曲模式有积极影响，但3%和5wt%组之间的刚度相似。总之，本研究证明了这些新型支架在骨再生应用方面具有巨大潜力，因此应进一步研究。
