Davidson Matthew D, Song Kwang Hoon, Lee Mu-Huan, Llewellyn Jessica, Du Yu, Baker Brendon M, Wells Rebecca G, Burdick Jason A
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
NSF Science and Technology Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
ACS Biomater Sci Eng. 2019 Aug 12;5(8):3899-3908. doi: 10.1021/acsbiomaterials.8b01276. Epub 2019 Mar 25.
Tissue fibrosis is a leading cause of mortality and is characterized by excessive protein deposition and altered tissue mechanical properties. In pathological fibrosis, as well as cancer related fibrosis, tissue pericytes and fibroblasts transition from a quiescent to a myofibroblastic phenotype. In vitro models are needed to better understand how these cells are influenced by their local microenvironment. Here, we developed a fibrous network platform to mimic the structure of the extracellular matrix, where fibers consist of cross-linked hyaluronic acid hydrogels with controlled cross-link density and mechanical properties. As a model myofibroblast precursor, primary hepatic stellate cells were seeded onto fibers with either low (soft) or high (stiff) cross-link density, either directly after isolation (quiescent) or following preculture on tissue culture plates (activated). In general, both quiescent and activated cells showed an increase in spreading, alpha smooth muscle actin expression, and the formation of multicellular clusters on soft fibers when compared to stiff fibers. Further, inhibition of alpha smooth muscle actin decreased activation of cells on soft fibers. This is likely due to fiber recruitment in soft fibers that increased local fiber density, whereas stiff fibers resisted recruitment. This work emphasizes the importance of substrate topography on cell-material interactions and shows that tunable fibrous hydrogels are a relevant culture platform for studying fibrosis and mechanotransduction in disease.
组织纤维化是导致死亡的主要原因，其特征是蛋白质过度沉积和组织力学性能改变。在病理性纤维化以及癌症相关纤维化中，组织周细胞和成纤维细胞会从静止状态转变为肌成纤维细胞表型。需要体外模型来更好地了解这些细胞如何受到其局部微环境的影响。在此，我们开发了一种纤维网络平台来模拟细胞外基质的结构，其中纤维由具有可控交联密度和力学性能的交联透明质酸水凝胶组成。作为模型肌成纤维细胞前体，原代肝星状细胞被接种到交联密度低（软）或高（硬）的纤维上，接种时间要么是在分离后直接接种（静止状态），要么是在组织培养板上预培养后接种（活化状态）。总体而言，与硬纤维相比，静止和活化细胞在软纤维上的铺展、α平滑肌肌动蛋白表达以及多细胞簇的形成均有所增加。此外，抑制α平滑肌肌动蛋白可降低细胞在软纤维上的活化。这可能是由于软纤维中的纤维募集增加了局部纤维密度，而硬纤维则抵抗募集。这项工作强调了底物拓扑结构对细胞 - 材料相互作用的重要性，并表明可调节的纤维水凝胶是研究疾病中纤维化和机械转导的相关培养平台。
