期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：37
页码：E5117-E5122
DOI：10.1073/pnas.1509663112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceMechanical interactions between cells, mediated by the elastic response of the extracellular matrix to active applied forces, play a critical role in developmental biology, wound healing, and cancer progression. This work applies sophisticated technical means, both in experiment and computational modeling, to investigate the micron-scale mechanics of a popular model of this medium, a collagen gel. The results obtained show clearly that on the cellular scale, there are significant spatial variations in the micromechanics due to network heterogeneities. Collagen gels are widely used in experiments on cell mechanics because they mimic the extracellular matrix in physiological conditions. Collagen gels are often characterized by their bulk rheology; however, variations in the collagen fiber microstructure and cell adhesion forces cause the mechanical properties to be inhomogeneous at the cellular scale. We study the mechanics of type I collagen on the scale of tens to hundreds of microns by using holographic optical tweezers to apply pN forces to microparticles embedded in the collagen fiber network. We find that in response to optical forces, particle displacements are inhomogeneous, anisotropic, and asymmetric. Gels prepared at 21 {degrees}C and 37 {degrees}C show qualitative difference in their micromechanical characteristics. We also demonstrate that contracting cells remodel the micromechanics of their surrounding extracellular matrix in a strain- and distance-dependent manner. To further understand the micromechanics of cellularized extracellular matrix, we have constructed a computational model which reproduces the main experiment findings.
