School of Biomedical Engineering and Sciences, Virginia Tech-Wake Forest University, Blacksburg, VA 24061, USA.
Biomaterials. 2011 Nov;32(31):7905-12. doi: 10.1016/j.biomaterials.2011.07.001. Epub 2011 Jul 22.
Cells cultured within a three-dimensional (3D) in vitro environment have the ability to acquire phenotypes and respond to stimuli analogous to in vivo biological systems. This approach has been utilized in tissue engineering and can also be applied to the development of a physiologically relevant in vitro tumor model. In this study, collagen I hydrogels cultured with MDA-MB-231 human breast cancer cells were bioengineered as a platform for in vitro solid tumor development. The cell-cell and cell-matrix interactions present during in vivo tissue progression were encouraged within the 3D hydrogel architecture, and the biocompatibility of collagen I supported unconfined cellular proliferation. The development of necrosis beyond a depth of ~150-200 μm and the expression of hypoxia-inducible factor (HIF)-1α were demonstrated in the in vitro bioengineered tumors. Oxygen and nutrient diffusion limitations through the collagen I matrix as well as competition for available nutrients resulted in growing levels of intra-cellular hypoxia, quantified by a statistically significant (p < 0.01) upregulation of HIF-1α gene expression. The bioengineered tumors also demonstrated promising angiogenic potential with a statistically significant (p < 0.001) upregulation of vascular endothelial growth factor (VEGF)-A gene expression. In addition, comparable gene expression analysis demonstrated a statistically significant increase of HIF-1α (p < 0.05) and VEGF-A (p < 0.001) by MDA-MB-231 cells cultured in the 3D collagen I hydrogels compared to cells cultured in a monolayer on two-dimensional tissue culture polystyrene. The results presented in this study demonstrate the capacity of collagen I hydrogels to facilitate the development of 3D in vitro bioengineered tumors that are representative of the pre-vascularized stages of in vivo solid tumor progression.
细胞在三维（3D）体外环境中培养时，能够获得类似于体内生物系统的表型并对刺激做出反应。这种方法已被用于组织工程，也可应用于开发具有生理相关性的体外肿瘤模型。在本研究中，使用 MDA-MB-231 人乳腺癌细胞培养的 I 型胶原水凝胶被生物工程化为体外实体瘤发展的平台。在 3D 水凝胶结构中鼓励了体内组织进展过程中存在的细胞-细胞和细胞-基质相互作用，并且 I 型胶原的生物相容性支持无限制的细胞增殖。在体外生物工程化肿瘤中，已经证明了超过 150-200μm 深度的坏死以及缺氧诱导因子（HIF）-1α的表达。通过 I 型胶原基质的氧气和营养扩散限制以及对可用营养物质的竞争，导致细胞内缺氧程度不断增加，通过 HIF-1α 基因表达的统计学显著（p < 0.01）上调来定量。生物工程化肿瘤还表现出有希望的血管生成潜力，血管内皮生长因子（VEGF）-A 基因表达的统计学显著（p < 0.001）上调。此外，可比的基因表达分析表明，与在二维组织培养聚苯乙烯上培养的细胞相比，在 3D I 型胶原水凝胶中培养的 MDA-MB-231 细胞中 HIF-1α（p < 0.05）和 VEGF-A（p < 0.001）的统计学显著增加。本研究中的结果表明，I 型胶原水凝胶具有促进 3D 体外生物工程化肿瘤发展的能力，这些肿瘤代表了体内实体瘤进展的预血管化阶段。
