Dose-dependent osteogenic effect of octacalcium phosphate on mouse bone marrow stromal cells
Dose-dependent osteogenic effect of octacalcium phosphate on mouse bone marrow stromal cells
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DOI：
10.1089/tea.2007.0339
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发表时间：
2008-06-01
影响因子：
4.1
通讯作者：
Suzuki, Osamu
中科院分区：
文献类型：
--
作者：
Anada, Takahisa;Kumagai, Takashi;Suzuki, Osamu
八磷酸钙（OCP）被认为是骨骼和牙齿中生物磷灰石晶体的前体。我们之前的研究表明，当植入骨缺损时，合成OCP刺激骨再生，随后OCP逐渐转化为羟基磷灰石（HA）。然而，OCP诱导成骨细胞成骨表型的确切机制尚未确定。本研究旨在探讨OCP结构特性的物理化学方面是否影响成骨细胞系小鼠骨髓基质ST-2细胞的功能。将不同量的合成OCP和合成烧结陶瓷HA涂覆在48孔组织培养板上。控制OCP和HA的含量以增强其内在的物理化学性质，在培养过程中，晶体周围的环境将被改变。OCP涂层的粗糙度与涂层量无关。对OCP涂层上清液的化学分析表明，随着OCP用量的增加，Ca2+浓度降低，而无机磷酸盐浓度明显增加，这很可能是通过OCP磷灰石转化而产生的。ST-2细胞在OCP或HA涂层上培养至第21天。OCP涂层引起细胞附着和增殖初始阶段的显著减少，这取决于涂层的量。另一方面，OCP增强了成骨标志物的表达，包括I型胶原、碱性磷酸酶和成骨细胞。然而，在不同剂量的HA包被上培养的ST-2细胞中，HA没有改变这些标记的表达。这些结果表明，OCP能够诱导基质细胞向成骨细胞分化，特别是在达到成熟成骨细胞谱系阶段之前分化为早期成骨细胞。
Octacalcium phosphate (OCP) has been advocated to be a precursor of biological apatite crystals in bones and teeth. Our previous studies showed that synthetic OCP stimulates bone regeneration, followed by the progressive conversion of OCP into hydroxyapatite (HA), when implanted in bone defects. However, the precise mechanism to induce the osteogenic phenotype in osteoblasts by OCP has not been identified. The present study was designed to investigate whether the physicochemical aspect, specific to and derived from the structural properties of OCP, influences the function of an osteoblastic cell line, mouse bone marrow stromal ST-2 cells. Different amounts of synthetic OCP and synthetic sintered ceramic HA were coated onto 48-well tissue culture plates. The amounts of OCP and HA were controlled to strengthen their intrinsic physicochemical properties, in which the milieu around the crystals will be modified during the culture. The roughness of the OCP coatings was independent of the amount of coating. Chemical analyses of the supernatants of the OCP coatings revealed that the concentration of Ca2+ decreased with increasing amounts of OCP, while the concentration of inorganic phosphate increased markedly, most probably through OCP apatite conversion. ST-2 cells were cultured on the OCP or HA coatings up to day 21. The OCP coating caused a significant decrease in cell attachment and in the initial stage of proliferation, dependent upon the amount of coating. On the other hand, OCP enhanced the expression of osteogenic markers, including type I collagen, alkaline phosphatase, and osterix. However, HA did not alter the expression of these markers in ST-2 cells cultured on different amounts of HA coating. These results demonstrated that OCP is capable of inducing the differentiation of stromal cells into osteoblastic cells, especially differentiation into early stage osteoblastic cells, prior to reaching the stage of mature osteoblastic cell lineage.