胶原蛋白促进成骨细胞在磷灰石基质上增殖和分化

Collagen Coating Improves the Bioactivity of Apatite Substrate in Osteoblast Proliferation and Differentiation

骨质主要由Ⅰ型胶原和磷灰石组成,并通过骨重建实现更新。在骨重建过程中,逆转期细胞改造破骨细胞留下的骨吸收表面,并沉积一层薄层蛋白质(主要是胶原蛋白)形成逆转线,这是骨吸收与骨形成偶联的必要步骤。胶原层对成骨细胞的生长和新骨质的形成至关重要。为了验证这一假设,本工作利用改良型模拟体液有效地制备了具有连续完整结构的类骨磷灰石基质,然后将该基质以及表面形成薄层胶原蛋白的基质培养成骨样细胞MC3T3-E1并诱导其分化,检测细胞粘附、增殖和两种成骨分化标志物的表达。结果表明,磷灰石基质上的成骨细胞表现出形态收缩、增殖和分化延迟,并倾向于在分化之前分泌更多的胶原蛋白。在形成薄层胶原蛋白的磷灰石基质上,成骨细胞保持铺展形态和较高的增殖率,并在诱导分化后表达高水平的碱性磷酸酶。这很可能表明,在骨重建过程中,逆转期细胞在骨吸收表面的磷灰石骨质上形成胶原蛋白对成骨细胞的附着、增殖和分化很重要。

Bone matrix is mainly composed of type I collagen and apatite and undergoes renewal during remodeling. During this process, reversal cells recondition the resorbed surfaces left by osteoclasts and deposit a thin layer of proteins (mainly collagen) to form reversal lines, this is an obligatory step in the link between bone resorption and formation. The collagen layer is critical for osteoblast growth and the formation of new bone matrix. In order to verify the hypothesis, we modified a widely accepted simulated body fluid by increasing the relative proportion of Ca 2+ and HPO 4 2- to effectively generate a continuous bone-like apatite substrate. Then the substrates with or without collagen pre-coating were used for MC3T3-E1 osteoblast-like cells culturing and inducing them to differentiate. The cell attachment, proliferation, and the expression of two osteogenic markers were detected. The results indicated that osteoblasts on an apatite substrate showed retracted morphologies and delayed proliferation and differentiation, and tended to secrete more collagen before they were committed to differentiation. After collagen coating of apatite substrates, osteoblasts maintained spreading morphology and higher proliferation rates, and expressed high levels of alkaline phosphatase after differentiation induction. This most probably indicated that the collagen pre-coated on apatite substrates, as deposited on the resorbed surface by reversal cells during bone remodeling, is important for osteoblast attachment, proliferation, and differentiation.