Osteogenic cell functionality on 3-dimensional nano-scaffolds with varying stiffness
Osteogenic cell functionality on 3-dimensional nano-scaffolds with varying stiffness
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DOI：
10.1016/j.eml.2017.01.002
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发表时间：
2017-05-01
影响因子：
4.7
通讯作者：
Greer, Julia R.
中科院分区：
文献类型：
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作者：
Maggi, Alessandro;Allen, Jessica;Greer, Julia R.
二十多年来，由于缺乏对三维 (3D) 环境中细胞行为的透彻了解，创建可实现最佳骨重塑的植入物一直是一个挑战。传统制造技术的局限性以及表征细胞与支架相互作用的困难限制了我们对支架孔径和分布以及刚度等因素如何影响细胞反应的理解。迄今为止，刚度范围从几 kPa 到数百 MPa 的 3D 基底上的细胞活动已得到广泛研究（Cui 等人， 2009；Fu 等人，2011；Hulbert 等人，1970；Johnson 和 Herschler，2011；Karageorgiou 和 Kaplan，2005。制造限制限制了支架尺寸为几微米（与成骨细胞尺寸相当）的支架，其压缩模量范围为 10 kPa 至 200 kPa，这限制了我们对支架刚度如何影响矿物质沉积的理解。压缩模量在 MPa 范围内且支柱尺寸在几微米量级的 3D 支架上的细胞活力和功能尚未有报道。我们采用双光子光刻技术创建了孔隙率接近 99%、支柱直径接近 2 μm、结构刚度接近 2-9 MPa 的周期性 3D 纳米结构，以探索在类似于天然骨的微环境中支架特性对成骨细胞活力的影响。这些纳米晶格由涂有不同材料的聚合物核心制成，并具有十四面体几何形状和 25 μm 孔径的晶胞。晶胞在空间中被镶嵌以形成横向尺寸为200×200μm、高度为50μm的晶格。一些聚合物纳米晶格涂有 120 nm 厚的共形 SiO2 层，其他聚合物纳米晶格涂有 120 nm 的 Ti。所有纳米晶格都具有类似 20 nm 厚的 TiO2 最外层。成骨细胞在纳米晶格上生长 28 天，并通过扫描电子显微镜 (SEM)、能量色散光谱 (EDS) 和拉曼光谱对所得细胞形态和沉积进行表征。这些分析揭示了明显的细胞附着和羟基磷灰石 (Ca-10(PO4)(6)(OH)(2))、磷酸三钙 (Ca-3(PO4)(2)) 和偏磷酸盐 ([ Ca-2(P2O7)] n) 的存在，这些化学物质通常存在于天然骨中。这种成骨功能表明，3维纳米结构材料可以用作细胞生长和增殖的有效支架，最终可以产生更好的骨植入物。 (C) 2017 Elsevier Ltd. 保留所有权利。
Creating implants that lead to optimal bone remodeling has been a challenge for more than two decades because of a lack of thorough knowledge of cell behavior in three-dimensional (3D) environments Limitations in traditional fabrication techniques and difficulties in characterizing cell-scaffold interactions have limited our understanding of how factors like scaffold pore size and distribution, as well as stiffness affect cell response.To date, cellular activity on 3D substrates with stiffness ranging from a few kPa to hundreds of MPa has been investigated extensively (Cui et al., 2009; Fu et al., 2011; Hulbert et al., 1970; Hollinger et al., 1996; Johnson and Herschler, 2011; Karageorgiou and Kaplan, 2005). Fabrication limitations have restricted scaffolds with strut dimensions on the order of a few microns, a size comparable to the dimensions of osteoblasts, to have compressive moduli ranging from 10 kPa to 200 kPa, which has limited our understanding of how scaffolds stiffness affects mineral deposition. Cell viability and functionality on 3D scaffolds with compressive moduli in the MPa range and with strut dimensions on the order of a few microns have not yet been reported. We employed two-photon lithography to create periodic 3D nano-architectures with similar to 99% porosity, similar to 2 mu m strut diameters, and similar to 2-9 MPa structural stiffness to explore the influence of scaffold properties on the viability of osteoblasts in a microenvironment similar to that of natural bone. These nanolattices were made out of a polymeric core coated with different materials and had unit cells with tetrakaidecahedral geometry and a 25 mu m pore size. The unit cells were tessellated in space to form a lattice with lateral dimensions of 200 x 200 mu m and a height of 50 mu m. Some of the polymer nanolattices were coated with a conformal 120 nm-thick layer of SiO2, others were coated with 120 nm of Ti. All nanolattices had a similar to 20 nm-thick outermost layer of TiO2. Osteogenic cells were grown on the nanolattices for 28 days and the resulting cell morphology and depositions were characterized via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy. These analyses revealed significant cell attachment and the presence of hydroxyapatite (Ca-10(PO4)(6)(OH)(2)), tricalcium phosphate (Ca-3(PO4)(2)) and metaphosphates ([ Ca-2(P2O7)] n), chemical species normally found in natural bone. Such osteogenic functionality suggests that 3-dimensional nanoarchitected materials can be used as effective scaffolds for cell growth and proliferation, which could eventually lead to the generation of better bone implants. (C) 2017 Elsevier Ltd. All rights reserved.