Introduction

Tissue fibrosis is characterized by progressive extracellular matrix (ECM) stiffening and loss of viscoelasticity that ultimately impairs organ functionality. Cells bind to the ECM through integrins, where αv integrin engagement in particular has been correlated with fibroblast activation into contractile myofibroblasts that drive fibrosis progression. There is a significant unmet need for in vitro hydrogel systems that deconstruct the complexity of native tissues to better understand the individual and combined effects of stiffness, viscoelasticity, and integrin engagement on fibroblast behavior.

Methods

We developed hyaluronic acid hydrogels with independently tunable cell-instructive properties (stiffness, viscoelasticity, ligand presentation) to address this challenge. Hydrogels with mechanics matching normal or fibrotic lung tissue were synthesized using a combination of covalent crosslinks and supramolecular interactions to tune viscoelasticity. Cell adhesion was mediated through incorporation of either RGD peptide or engineered fibronectin fragments promoting preferential integrin engagement via αvβ3 or α5β1.

Results

On fibrosis-mimicking stiff elastic hydrogels, preferential αvβ3 engagement promoted increased spreading, actin stress fiber organization, and focal adhesion maturation as indicated by paxillin organization in human lung fibroblasts. In contrast, preferential α5β1 binding suppressed these metrics. Viscoelasticity, mimicking the mechanics of healthy tissue, largely curtailed fibroblast spreading and focal adhesion organization independent of adhesive ligand type, highlighting its role in reducing fibroblast-activating behaviors.

Conclusions

Together, these results provide new insights into how mechanical and adhesive cues collectively guide disease-relevant cell behaviors.

中文翻译：

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粘弹性和粘附线索对成纤维细胞扩散和局部粘附组织的综合影响

介绍

组织纤维化的特征是进行性细胞外基质 (ECM) 硬化和粘弹性丧失，最终损害器官功能。细胞通过整合素与 ECM结合，尤其是αv整合素参与与成纤维细胞激活成可收缩的肌成纤维细胞相关，从而驱动纤维化进展。解构天然组织的复杂性以更好地了解刚度、粘弹性和整合素参与对成纤维细胞行为的个体和综合影响的体外水凝胶系统存在显着未满足的需求。

方法

我们开发了具有独立可调的细胞指导特性（刚度、粘弹性、配体呈递）的透明质酸水凝胶来应对这一挑战。使用共价交联和超分子相互作用的组合来调节粘弹性，合成了具有与正常或纤维化肺组织匹配的力学的水凝胶。细胞粘附是通过掺入 RGD 肽或工程化纤连蛋白片段介导的，通过αvβ 3 或α 5 β 1 促进整合素优先参与。

结果

在模拟纤维化的刚性弹性水凝胶上，αvβ 3 的优先参与促进了增加的扩散、肌动蛋白应力纤维组织和粘着斑成熟，如人肺成纤维细胞中桩蛋白组织所示。相反，优先的α 5 β 1 结合抑制了这些指标。粘弹性，模仿健康组织的力学，大大减少了成纤维细胞的扩散和粘着斑组织，与粘合剂配体类型无关，突出了其在减少成纤维细胞激活行为中的作用。

结论

总之，这些结果为机械和粘附线索如何共同指导与疾病相关的细胞行为提供了新的见解。