Wang Juan, Koelbl Joseph, Boddupalli Anuraag, Yao Zhiqi, Bratlie Kaitlin M, Schneider Ian C
Department of Chemical and Biological Engineering, Iowa State University, USA.
Integr Biol (Camb). 2018 Nov 12;10(11):705-718. doi: 10.1039/c8ib00127h.
Contact guidance or bidirectional migration along aligned fibers modulates many physiological and pathological processes such as wound healing and cancer invasion. Aligned 2D collagen fibrils epitaxially grown on mica substrates replicate many features of contact guidance seen in aligned 3D collagen fiber networks. However, these 2D collagen self-assembled substrates are difficult to image through, do not have known or tunable mechanical properties and cells degrade and mechanically detach collagen fibrils from the surface, leading to an inability to assess contact guidance over long times. Here, we describe the transfer of aligned collagen fibrils from mica substrates to three different functionalized target substrates: glass, polydimethylsiloxane (PDMS) and polyacrylamide (PA). Aligned collagen fibrils can be efficiently transferred to all three substrates. This transfer resulted in substrates that were to varying degrees resistant to cell-mediated collagen fibril deformation that resulted in detachment of the collagen fibril field, allowing for contact guidance to be observed over longer time periods. On these transferred substrates, cell speed is lowest on softer contact guidance cues for both MDA-MB-231 and MTLn3 cells. Intermediate stiffness resulted in the fastest migration. MTLn3 cell directionality was low on soft contact guidance cues, whereas MDA-MB-231 cell directionality marginally increased. It appears that the stiffness of the contact guidance cue regulates contact guidance differently between cell types. The development of this collagen fibril transfer method allows for the attachment of aligned collagen fibrils on substrates, particularly flexible substrates, that do not normally promote aligned collagen fibril growth, increasing the utility of this collagen self-assembly system for the fundamental examination of mechanical regulation of contact guidance.
沿着排列的纤维进行接触导向或双向迁移调节着许多生理和病理过程，如伤口愈合和癌症侵袭。在云母基底上外延生长的二维排列胶原纤维复制了三维排列胶原纤维网络中接触导向的许多特征。然而，这些二维胶原自组装基底难以进行穿透成像，没有已知的或可调节的力学性能，并且细胞会降解并使胶原纤维从表面机械性脱离，导致无法长时间评估接触导向。在此，我们描述了将排列的胶原纤维从云母基底转移到三种不同功能化的目标基底：玻璃、聚二甲基硅氧烷（PDMS）和聚丙烯酰胺（PA）。排列的胶原纤维能够有效地转移到所有这三种基底上。这种转移产生了在不同程度上抵抗细胞介导的胶原纤维变形的基底，这种变形会导致胶原纤维场的脱离，从而能够在更长的时间段内观察到接触导向。在这些转移的基底上，对于MDA - MB - 231和MTLn3细胞而言，在较软的接触导向线索上细胞速度最低。中等硬度导致迁移速度最快。在软接触导向线索上MTLn3细胞的方向性较低，而MDA - MB - 231细胞的方向性略有增加。看来接触导向线索的硬度对不同细胞类型的接触导向调节方式不同。这种胶原纤维转移方法的开发使得排列的胶原纤维能够附着在通常不促进排列胶原纤维生长的基底上，特别是柔性基底上，增加了这种胶原自组装系统在接触导向机械调节基础研究中的实用性。
