Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY 12180, United States; Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY 12180, United States.
Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY 12180, United States; Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY 12180, United States.
Acta Biomater. 2020 May;108:128-141. doi: 10.1016/j.actbio.2020.03.019. Epub 2020 Mar 17.
Stromal collagen is upregulated surrounding a solid tumor and presents as dense, thick, linearized, and aligned bundles. The collagen bundles are continually remodeled during tumor progression, and their orientation with respect to the tumor boundary has been correlated with invasive state. Currently, reconstituted-collagen gels are the standard in vitro tumor cell-extracellular matrix interaction model. The reticular, dense, and isotropic nanofiber (~900 nm-diameter, on average) gels do not, however, recapitulate the in vivo structural features of collagen bundling and alignment. Here, we present a rapid and simple method to fabricate bundles of collagen type I, whose average thickness may be varied between about 4 μm and 9 μm dependent upon diluent temperature and ionic strength. The durability and versatility of the collagen bundles was demonstrated with their incorporation into two in vitro models where the thickness and alignment of the collagen bundles resembled various in vivo arrangements. First, collagen bundles aligned by a microfluidic device elicited cancer cell contact guidance and enhanced their directional migration. Second, the presence of the collagen bundles in a bio-inert agarose hydrogel was shown to provide a route for cancer cell outgrowth. The unique structural features of the collagen bundles advance the physiological relevance of in vitro collagen-based tumor models for accurately capturing tumor cell-extracellular matrix interactions. STATEMENT OF SIGNIFICANCE: Collagen in the tumor microenvironment is upregulated and remodeled into dense, thick, and aligned bundles that are associated with invasive state. Current collagen-based in vitro models are based on reticular, isotropic nanofiber gels that do not fully recapitulate in vivo tumor stromal collagen. We present a simple and robust method of rapidly fabricating cell-scale collagen bundles that better mimic the remodeled collagen surrounding a tumor. Interacting with the bundles, cancer cells exhibited drastically different phenotypic behaviors, compared to nanofiber scaffolds. This work reveals the importance of microscale architecture of in vitro tumor models. The collagen bundles provide physiologically relevant collagen morphologies that may be easily incorporated into existing models of tumor cell-extracellular matrix interactions.
基质胶原在实体瘤周围上调，并呈现密集、厚实、线性化和对齐的束状。在肿瘤进展过程中，胶原束不断重塑，其相对于肿瘤边界的方向与浸润状态相关。目前，重组胶原凝胶是体外肿瘤细胞-细胞外基质相互作用模型的标准。然而，网状、密集和各向同性的纳米纤维凝胶（~900nm 直径，平均）并不能再现胶原束和排列的体内结构特征。在这里，我们提出了一种快速而简单的方法来制备 I 型胶原束，其平均厚度可以根据稀释剂温度和离子强度在约 4μm 和 9μm 之间变化。通过将胶原束纳入两种体外模型中，证明了胶原束的耐用性和多功能性，其中胶原束的厚度和排列类似于各种体内排列。首先，通过微流控装置排列的胶原束引发了癌细胞的接触引导，并增强了它们的定向迁移。其次，在惰性琼脂糖水凝胶中存在胶原束被证明为癌细胞外生提供了途径。胶原束的独特结构特征提高了体外基于胶原的肿瘤模型在准确捕获肿瘤细胞-细胞外基质相互作用方面的生理相关性。意义声明：肿瘤微环境中的胶原上调并重塑为密集、厚实和对齐的束状，与浸润状态相关。目前基于胶原的体外模型基于网状、各向同性纳米纤维凝胶，不能完全再现体内肿瘤基质胶原。我们提出了一种简单而强大的快速制备细胞尺度胶原束的方法，这种方法更好地模拟了肿瘤周围重塑的胶原。与束状结构相互作用时，与纳米纤维支架相比，癌细胞表现出截然不同的表型行为。这项工作揭示了体外肿瘤模型微结构的重要性。胶原束提供了更具生理相关性的胶原形态，可轻松纳入现有的肿瘤细胞-细胞外基质相互作用模型。
