Faculdade de Medicina Dentária, Laboratory for Bone Metabolism and Regeneration, Universidade do Porto, Porto 4200-393, Portugal; LAQV/REQUIMTE, U. Porto, Porto 4160-007, Portugal.
Centro Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
Mater Sci Eng C Mater Biol Appl. 2020 Oct;115:111147. doi: 10.1016/j.msec.2020.111147. Epub 2020 Jun 2.
The development of biomaterials that mimicking the hydroxyapatite nanoparticles existent in the immature bone tissue is crucial, especially to accelerate the bone remodeling and regeneration. In this work, it was developed for the first time, hydroxyapatite nanoparticles (NPs) incorporating citrate and zinc (cit-Zn-Hap) in their composition towards a one-step hydrothermal procedure. For comparison purposes, hydroxyapatite NPs incorporating only zinc (Zn-Hap) or citrate (cit-Hap), as well as hydroxyapatite without any of these elements (Hap) were synthesised. The physicochemical characterization was carried out reveling that, the presence of zinc on hydroxyapatite (cit-Zn-Hap), reduced the size of nanoparticles, changed the phosphate environment and decreased the surface charge when compared with cit-Hap nanoparticles. The osteogenic potential of cit-Zn-Hap NPs was analysed in human bone marrow-derived stromal cells (BMSCs), in the absence of osteoinductive factors. NPs were internalized by endocytosis appearing trapped in endosomes and lysosomes scattered through the cytoplasm. Exposure to these NPs resulted in a significant induction of ALP activity, extracellular matrix mineralization, and gene expression of early and later osteogenic transcription factors, as well as of osteoblastic markers. The osteoinductive effect might be regulated, at least in part, by the increased signalling through the canonical WNT pathway. Evaluation of the cell behaviour following exposure to Zn-Hap and cit-Hap strongly suggested a synergistic effect of citrate and Zn in cit-Zn-Hap NPs towards the induction of the osteogenic commitment and functionality of BMSCs. These findings will allow the design of new biomimetic hydroxyapatite nanoparticles with great potential for bone regeneration.
开发模仿未成熟骨组织中存在的羟磷灰石纳米粒子的生物材料至关重要，尤其是为了加速骨重塑和再生。在这项工作中，首次通过一步水热法开发了在其组成中掺入柠檬酸盐和锌的羟磷灰石纳米粒子（NPs）（cit-Zn-Hap）。出于比较目的，还合成了仅掺入锌（Zn-Hap）或柠檬酸盐（cit-Hap）的羟磷灰石 NPs 以及不含任何这些元素的羟磷灰石（Hap）。进行了物理化学特性研究，结果表明，锌的存在于羟磷灰石（cit-Zn-Hap）中，降低了纳米粒子的尺寸，改变了磷酸盐环境并降低了表面电荷，与 cit-Hap 纳米粒子相比。在缺乏成骨诱导因子的情况下，分析了 cit-Zn-Hap NPs 对人骨髓基质细胞（BMSCs）的成骨潜力。纳米粒子通过内吞作用被内化，出现在散布在细胞质中的内体和溶酶体中被困住。暴露于这些 NPs 会导致碱性磷酸酶（ALP）活性、细胞外基质矿化以及早期和晚期成骨转录因子以及成骨细胞标志物的基因表达显著增加。成骨诱导作用可能至少部分受经典 WNT 途径的信号转导增加调节。暴露于 Zn-Hap 和 cit-Hap 后对细胞行为的评估强烈表明，在 cit-Zn-Hap NPs 中，柠檬酸和 Zn 之间存在协同作用，可诱导 BMSCs 的成骨承诺和功能。这些发现将允许设计具有巨大骨再生潜力的新型仿生羟磷灰石纳米粒子。
