Parekh Sapun H, Chatterjee Kaushik, Lin-Gibson Sheng, Moore Nicole M, Cicerone Marcus T, Young Marian F, Simon Carl G
Polymers Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8543, USA.
Biomaterials. 2011 Mar;32(9):2256-64. doi: 10.1016/j.biomaterials.2010.11.065. Epub 2010 Dec 21.
Proliferation and differentiation of cells are known to be influenced by the physical properties of the extracellular environment. Previous studies examining biophysics underlying cell response to matrix stiffness utilized a two-dimensional (2D) culture format, which is not representative of the three-dimensional (3D) tissue environment in vivo. We report on the effect of 3D matrix modulus on human bone marrow stromal cell (hBMSC) differentiation. hBMSCs underwent osteogenic differentiation in poly(ethylene glycol) hydrogels of all modulus (300-fold modulus range, from 0.2 kPa to 59 kPa) in the absence of osteogenic differentiation supplements. This osteogenic differentiation was modulus-dependent and was enhanced in stiffer gels. Osteogenesis in these matrices required integrin-protein ligation since osteogenesis was inhibited by soluble Arginine-Glycine-Aspartate-Serine peptide, which blocks integrin receptors. Immunostained images revealed lack of well-defined actin filaments and microtubules in the encapsulated cells. Disruption of mechanosensing elements downstream of integrin binding that have been identified from 2D culture such as actin filaments, myosin II contraction, and RhoA kinase did not abrogate hBMSC material-driven osteogenic differentiation in 3D. These data show that increased hydrogel modulus enhanced osteogenic differentiation of hBMSCs in 3D scaffolds but that hBMSCs did not use the same mechanosensing pathways that have been identified in 2D culture.
已知细胞的增殖和分化会受到细胞外环境物理特性的影响。以往研究细胞对基质硬度反应背后生物物理学的实验采用的是二维（2D）培养模式，这种模式无法代表体内的三维（3D）组织环境。我们报告了三维基质模量对人骨髓间充质干细胞（hBMSC）分化的影响。在没有成骨分化补充剂的情况下，hBMSC在所有模量（模量范围为300倍，从0.2千帕到59千帕）的聚（乙二醇）水凝胶中发生成骨分化。这种成骨分化是模量依赖性的，在更硬的凝胶中会增强。这些基质中的成骨作用需要整合素-蛋白质连接，因为成骨作用会被可溶性精氨酸-甘氨酸-天冬氨酸-丝氨酸肽抑制，该肽会阻断整合素受体。免疫染色图像显示，被包裹的细胞中缺乏明确的肌动蛋白丝和微管。从二维培养中已确定的整合素结合下游机械传感元件的破坏，如肌动蛋白丝、肌球蛋白II收缩和RhoA激酶，并没有消除三维中hBMSC材料驱动的成骨分化。这些数据表明，水凝胶模量的增加增强了三维支架中hBMSC的成骨分化，但hBMSC并未使用二维培养中已确定的相同机械传感途径。
