Robust Pore Size Analysis of Filamentous Networks from Three-Dimensional Confocal Microscopy
Robust Pore Size Analysis of Filamentous Networks from Three-Dimensional Confocal Microscopy
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DOI：
10.1529/biophysj.108.135939
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发表时间：
2008-12-15
影响因子：
3.4
通讯作者：
Schroeder-Turk, Gerd E.
中科院分区：
文献类型：
--
作者：
Mickel, Walter;Muenster, Stefan;Schroeder-Turk, Gerd E.
我们描述了一种鲁棒的方法来确定形态学性质。从共聚焦显微镜图像堆中得到的膜状生物聚合物网络，如胶原或其他结缔组织基质。包括孔径分布和渗透阈值在内的形态特性对转运过程很重要，例如，颗粒扩散或细胞通过细胞外基质迁移。该方法适用于由大鼠尾肌腱和小牛皮肤胶原蛋白制备的荧光标记纤维网络，浓度为1.2、1.6和2.4 mg/ml。胶原纤维形成一个缠绕的分支网络。通过阈值强度分割和距离有序同伦稀疏，从图像堆栈中提取代表胶原纤维的内轴线或骨架。流体孔隙的大小由胶原纤维之间空隙中最大球体的半径定义，该半径来自于欧几里得距离图和流体相的最大覆盖半径变换。在水平方向和垂直方向上，计算出在胶原纤维之间穿过整个探针的流体相的最大球体的大小，称为渗透阈值。我们证明，通过将纤维表示为中间轴，衍生的形态网络特性对分割阈值强度的变化具有鲁棒性，并且对与成像系统的点扩散函数相关的问题具有鲁棒性。我们还为最近的一项声明提供了经验支持，即光纤网络的渗透阈值接近于网络的欧拉指数为零的光纤直径。
We describe a robust method for determining morphological properties of. lamentous biopolymer networks, such as collagen or other connective tissue matrices, from confocal microscopy image stacks. Morphological properties including pore size distributions and percolation thresholds are important for transport processes, e. g., particle diffusion or cell migration through the extracellular matrix. The method is applied to fluorescently labeled fiber networks prepared from rat-tail tendon and calf-skin collagen, at concentrations of 1.2, 1.6, and 2.4 mg/ml. The collagen fibers form an entangled and branched network. The medial axes, or skeletons, representing the collagen fibers are extracted from the image stack by threshold intensity segmentation and distance-ordered homotopic thinning. The size of the fiuid pores as defined by the radii of largest spheres that fit into the cavities between the collagen fibers is derived from Euclidean distance maps and maximal covering radius transforms of the fluid phase. The size of the largest sphere that can traverse the fluid phase between the collagen fibers across the entire probe, called the percolation threshold, was computed for both horizontal and vertical directions. We demonstrate that by representing the fibers as the medial axis the derived morphological network properties are both robust against changes of the value of the segmentation threshold intensity and robust to problems associated with the point-spread function of the imaging system. We also provide empirical support for a recent claim that the percolation threshold of a fiber network is close to the fiber diameter for which the Euler index of the networks becomes zero.