Buchanan Cara F, Voigt Elizabeth E, Szot Christopher S, Freeman Joseph W, Vlachos Pavlos P, Rylander Marissa Nichole
1 School of Biomedical Engineering and Sciences, Virginia Tech-Wake Forest University , Blacksburg, Virginia.
Tissue Eng Part C Methods. 2014 Jan;20(1):64-75. doi: 10.1089/ten.TEC.2012.0731. Epub 2013 Jul 12.
Hyperpermeable tumor vessels are responsible for elevated interstitial fluid pressure and altered flow patterns within the tumor microenvironment. These aberrant hydrodynamic stresses may enhance tumor development by stimulating the angiogenic activity of endothelial cells lining the tumor vasculature. However, it is currently not known to what extent shear forces affect endothelial organization or paracrine signaling during tumor angiogenesis. The objective of this study was to develop a three-dimensional (3D), in vitro microfluidic tumor vascular model for coculture of tumor and endothelial cells under varying flow shear stress conditions. A central microchannel embedded within a collagen hydrogel functions as a single neovessel through which tumor-relevant hydrodynamic stresses are introduced and quantified using microparticle image velocimetry (μ-PIV). This is the first use of μ-PIV in a tumor representative, 3D collagen matrix comprised of cylindrical microchannels, rather than planar geometries, to experimentally measure flow velocity and shear stress. Results demonstrate that endothelial cells develop a confluent endothelium on the microchannel lumen that maintains integrity under physiological flow shear stresses. Furthermore, this system provides downstream molecular analysis capability, as demonstrated by quantitative RT-PCR, in which, tumor cells significantly increase expression of proangiogenic genes in response to coculture with endothelial cells under low flow conditions. This work demonstrates that the microfluidic in vitro cell culture model can withstand a range of physiological flow rates and permit quantitative measurement of wall shear stress at the fluid-collagen interface using μ-PIV optical flow diagnostics, ultimately serving as a versatile platform for elucidating the role of fluid forces on tumor-endothelial cross talk.
高通透性的肿瘤血管导致肿瘤微环境中间质流体压力升高和血流模式改变。这些异常的流体动力应力可能通过刺激肿瘤血管内衬内皮细胞的血管生成活性来促进肿瘤发展。然而，目前尚不清楚剪切力在肿瘤血管生成过程中对内皮组织或旁分泌信号传导的影响程度。本研究的目的是开发一种三维（3D）体外微流控肿瘤血管模型，用于在不同的流动剪切应力条件下共培养肿瘤细胞和内皮细胞。嵌入胶原水凝胶中的中央微通道作为单个新血管，通过该通道引入与肿瘤相关的流体动力应力，并使用微粒图像测速技术（μ-PIV）进行量化。这是首次在由圆柱形微通道而非平面几何结构组成的具有肿瘤代表性的3D胶原基质中使用μ-PIV来实验测量流速和剪切应力。结果表明，内皮细胞在微通道内腔形成融合的内皮，在生理流动剪切应力下保持完整性。此外，该系统提供下游分子分析能力，定量RT-PCR证明，在低流量条件下，肿瘤细胞与内皮细胞共培养时，促血管生成基因的表达显著增加。这项工作表明，微流控体外细胞培养模型可以承受一系列生理流速，并允许使用μ-PIV光流诊断技术在流体-胶原界面定量测量壁面剪切应力，最终作为一个通用平台来阐明流体力在肿瘤-内皮细胞相互作用中的作用。
