Jones Christopher A R, Cibula Matthew, Feng Jingchen, Krnacik Emma A, McIntyre David H, Levine Herbert, Sun Bo
Department of Physics, Oregon State University, Corvallis, OR 97331;
Center of Theoretical Biophysics, Rice University, Houston, TX 77005; Department of Bioengineering, Rice University, Houston, TX 77005;
Proc Natl Acad Sci U S A. 2015 Sep 15;112(37):E5117-22. doi: 10.1073/pnas.1509663112. Epub 2015 Aug 31.
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 °C and 37 °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.
胶原凝胶在细胞力学实验中被广泛应用，因为它们在生理条件下模拟细胞外基质。胶原凝胶通常通过其整体流变学特性来表征；然而，胶原纤维微观结构和细胞粘附力的变化会导致其在细胞尺度上的力学性能不均匀。我们使用全息光镊对嵌入胶原纤维网络中的微粒施加皮牛级别的力，研究了几十到几百微米尺度上I型胶原的力学特性。我们发现，在光力作用下，微粒的位移是不均匀、各向异性和不对称的。在21℃和37℃制备的凝胶在其微观力学特性上表现出质的差异。我们还证明，收缩细胞以应变和距离依赖的方式重塑其周围细胞外基质的微观力学。为了进一步了解细胞化细胞外基质的微观力学，我们构建了一个计算模型，该模型再现了主要实验结果。
