Ghosh Deepraj, Lili Loukia, McGrail Daniel J, Matyunina Lilya V, McDonald John F, Dawson Michelle R
1 Georgia Institute of Technology , School of Chemical and Biomolecular Engineering, Atlanta, Georgia .
Stem Cells Dev. 2014 Feb 1;23(3):245-61. doi: 10.1089/scd.2013.0240. Epub 2013 Nov 8.
Mesenchymal stem cells (MSCs) play an important role in matrix remodeling, fibroblast activation, angiogenesis, and immunomodulation and are an integral part of fibrovascular networks that form in developing tissues and tumors. The engraftment and function of MSCs in tissue niches is regulated by a multitude of soluble proteins. Transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor-BB (PDGF) have previously been recognized for their role in MSC biology; thus, we sought to investigate their function in mediating MSC mechanics and matrix interactions. Cytoskeletal organization, characterized by cell elongation, stress fiber formation, and condensation of actin and microtubules, was dramatically affected by TGF-β1, individually and in combination with PDGF. The intracellular mechanical response to these stimuli was measured with particle tracking microrheology. MSCs stiffened in response to TGF-β1 (their elastic moduli was ninefold higher than control cells), a result that was enhanced by the addition of PDGF (100-fold change). Blocking TGF-β1 or PDGF signaling with inhibitors SB-505124 or JNJ-10198409, respectively, reversed soluble-factor-induced stiffening, indicating that crosstalk between these two pathways is essential for stiffening response. A genome-wide microarray analysis revealed TGF-β1-dependent regulation of cytoskeletal actin-binding protein genes. Actin crosslinking and bundling protein genes, which regulate cytosolic rheology through changes in semiflexible actin polymer meshwork, were upregulated with TGF-β1 treatment. TGF-β1 alone and in combination with PDGF also amplified surface integrin expression and adhesivity of MSCs with extracellular matrix proteins. These findings will provide a more mechanistic insight for modeling tissue-level rigidity in fibrotic tissues and tumors.
间充质干细胞（MSCs）在基质重塑、成纤维细胞激活、血管生成和免疫调节中发挥着重要作用，并且是在发育中的组织和肿瘤中形成的纤维血管网络的一个组成部分。MSCs在组织微环境中的植入和功能受多种可溶性蛋白质的调节。转化生长因子-β1（TGF-β1）和血小板衍生生长因子-BB（PDGF）先前已因其在MSCs生物学中的作用而被认可；因此，我们试图研究它们在介导MSCs力学和基质相互作用中的功能。以细胞伸长、应力纤维形成以及肌动蛋白和微管的凝聚为特征的细胞骨架组织受到TGF-β1单独作用以及与PDGF联合作用的显著影响。通过粒子追踪微流变学测量对这些刺激的细胞内力学反应。MSCs对TGF-β1产生硬化反应（其弹性模量比对照细胞高九倍），添加PDGF可增强这一结果（变化达100倍）。分别用抑制剂SB-505124或JNJ-10198409阻断TGF-β1或PDGF信号传导，可逆转可溶性因子诱导的硬化，表明这两条途径之间的串扰对于硬化反应至关重要。全基因组微阵列分析揭示了TGF-β1对细胞骨架肌动蛋白结合蛋白基因的依赖性调节。通过半柔性肌动蛋白聚合物网络的变化来调节胞质流变学的肌动蛋白交联和束集蛋白基因在TGF-β1处理后上调。单独的TGF-β1以及与PDGF联合使用也增强了MSCs的表面整合素表达以及与细胞外基质蛋白的粘附性。这些发现将为纤维化组织和肿瘤中组织水平刚性的建模提供更具机械性的见解。
