Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli.
Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli.
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DOI：
10.1371/journal.pone.0170312
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Schwartz Z
中科院分区：
文献类型：
--
作者：
Olivares-Navarrete R;Lee EM;Smith K;Hyzy SL;Doroudi M;Williams JK;Gall K;Boyan BD;Schwartz Z
干细胞的命运与其底层基质的机械性质有关，影响机械感受器并最终导致下游生物反应。研究已经使用聚合物来模拟细胞外基质以及个体组织的刚度，并且显示间充质干细胞（MSC）可以沿着沿着特定谱系定向。在这项研究中，我们研究了刚度在MSC分化为两种密切相关的细胞表型：成骨细胞和软骨细胞中的作用。通过改变单体浓度制备了四种弹性模量在0.1 ~ 310 MPa范围内的丙烯酸甲酯/甲基丙烯酸甲酯（MA/MMA）聚合物表面。将MSC在无外源性生长因子的培养基中培养，并将其生物学反应与定向软骨细胞和成骨细胞进行比较。当MSC在刚度<10 MPa的基质上生长时，软骨形成和成骨标志物均升高。与软骨细胞一样，在较低刚度基质上的MSC显示ACAN、SOX 9和COL 2的表达和蛋白多糖含量升高; COMP在MSC中升高，但在软骨细胞中降低。底物硬度改变了成骨细胞中RUNX 2 mRNA、碱性磷酸酶比活性、骨钙素和骨保护素的水平，降低了最不坚硬底物的水平。整合素亚基α1、α2、α5、αv、β1和β3的表达以刚度和细胞类型依赖性方式变化。MSC中整合素β 1亚基（ITGB 1）的沉默消除了基质硬度对成骨细胞和软骨细胞分化的影响。我们的研究结果表明，基质硬度是成骨细胞和软骨细胞分化的重要介质，整合素β1在这一过程中起着关键作用。
Stem cell fate has been linked to the mechanical properties of their underlying substrate, affecting mechanoreceptors and ultimately leading to downstream biological response. Studies have used polymers to mimic the stiffness of extracellular matrix as well as of individual tissues and shown mesenchymal stem cells (MSCs) could be directed along specific lineages. In this study, we examined the role of stiffness in MSC differentiation to two closely related cell phenotypes: osteoblast and chondrocyte. We prepared four methyl acrylate/methyl methacrylate (MA/MMA) polymer surfaces with elastic moduli ranging from 0.1 MPa to 310 MPa by altering monomer concentration. MSCs were cultured in media without exogenous growth factors and their biological responses were compared to committed chondrocytes and osteoblasts. Both chondrogenic and osteogenic markers were elevated when MSCs were grown on substrates with stiffness <10 MPa. Like chondrocytes, MSCs on lower stiffness substrates showed elevated expression of ACAN, SOX9, and COL2 and proteoglycan content; COMP was elevated in MSCs but reduced in chondrocytes. Substrate stiffness altered levels of RUNX2 mRNA, alkaline phosphatase specific activity, osteocalcin, and osteoprotegerin in osteoblasts, decreasing levels on the least stiff substrate. Expression of integrin subunits α1, α2, α5, αv, β1, and β3 changed in a stiffness- and cell type-dependent manner. Silencing of integrin subunit beta 1 (ITGB1) in MSCs abolished both osteoblastic and chondrogenic differentiation in response to substrate stiffness. Our results suggest that substrate stiffness is an important mediator of osteoblastic and chondrogenic differentiation, and integrin β1 plays a pivotal role in this process.