Matrix stiffness changes affect astrocyte phenotype in an in vitro injury model
Matrix stiffness changes affect astrocyte phenotype in an in vitro injury model
复制标题
基质硬度变化影响体外损伤模型中的星形胶质细胞表型
DOI：
10.1038/s41427-021-00304-0
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发表时间：
2021-04-16
影响因子：
9.7
通讯作者：
Xu, Feng
中科院分区：
文献类型：
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作者：
Hu, Yan;Huang, Guoyou;Xu, Feng
中枢神经系统（CNS）损伤通常导致星形胶质细胞活化，随后形成胶质瘢痕。已发现体内活性星形胶质细胞的胶质瘢痕的形成依赖于细胞微环境。然而，星形胶质细胞如何在瘢痕形成过程中对不同的微环境信号做出反应，例如基质硬度的变化，仍然是难以捉摸的。在这项工作中，我们建立了一个体外模型，以评估星形胶质细胞对基质硬度变化的反应，这可能与病理生理学有关。所研究的水凝胶骨架由I型胶原和藻酸盐组成。这些杂化水凝胶的刚度可以通过分别添加氯化钙的交联剂或柠檬酸钠的解交联剂来通过藻酸盐链的缔合或解离而动态地改变。我们发现星形胶质细胞在不同硬度的水凝胶中培养时获得不同的表型。当在细胞存在下改变基质刚度时，所获得的表型可以原位切换。具体来说，在3D中，基质硬化会逆转星形胶质细胞增生，而基质软化会启动星形胶质细胞激活。此外，基质硬度对星形胶质细胞活化的影响是由Yes相关蛋白（雅普）介导的，其中雅普抑制增强GFAP的上调并有助于星形胶质细胞增生。为了研究基质刚度依赖性GFAP表达的潜在机制，我们还开发了一个数学模型来描述星形胶质细胞基质刚度机械转导过程中生物分子的时间依赖性动力学。建模结果进一步表明，基质硬度对细胞命运和行为的影响可能与细胞骨架的变化和随后的雅普活性有关。这项研究的结果将指导研究人员重新研究基质硬度在体内反应性星形胶质细胞增生中的作用，并激发开发一种新的治疗方法，用于控制损伤后的胶质瘢痕形成，使轴突再生和改善功能恢复通过利用机械生物学研究的益处。
Injury to the central nervous system (CNS) usually leads to the activation of astrocytes, followed by glial scar formation. The formation of glial scars from active astrocytes in vivo has been found to be dependent on the cell microenvironment. However, how astrocytes respond to different microenvironmental cues during scar formation, such as changes in matrix stiffness, remains elusive. In this work, we established an in vitro model to assess the responses of astrocytes to matrix stiffness changes that may be related to pathophysiology. The investigated hydrogel backbones are composed of collagen type I and alginate. The stiffness of these hybrid hydrogels can be dynamically changed by association or dissociation of alginate chains through adding crosslinkers of calcium chloride or a decrosslinker of sodium citrate, respectively. We found that astrocytes obtain different phenotypes when cultured in hydrogels of different stiffnesses. The obtained phenotypes can be switched in situ when changing matrix stiffness in the presence of cells. Specifically, matrix stiffening reverts astrogliosis, whereas matrix softening initiates astrocytic activation in 3D. Moreover, the effect of matrix stiffness on astrocytic activation is mediated by Yes-associated protein (YAP), where YAP inhibition enhances the upregulation of GFAP and contributes to astrogliosis. To investigate the underlying mechanism of matrix stiffness-dependent GFAP expression, we also developed a mathematical model to describe the time-dependent dynamics of biomolecules involved in the matrix stiffness mechanotransduction process of astrocytes. The modeling results further indicate that the effect of matrix stiffness on cell fate and behavior may be related to changes in the cytoskeleton and subsequent activity of YAP. The results from this study will guide researchers to re-examine the role of matrix stiffness in reactive astrogliosis in vivo and inspire the development of a novel therapeutic approach for controlling glial scar formation following injury, enabling axonal regrowth and improving functional recovery by exploiting the benefits of mechanobiology studies.