Foty Ramsey
Department of Surgery, UMDNJ-Robert Wood Johnson Medical School, USA.
J Vis Exp. 2011 May 6(51):2720. doi: 10.3791/2720.
Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells within a tissue, however, are typically encased within a closely packed tissue mass in which cells establish intimate connections with many near-neighbors and with extracellular matrix components. Accordingly, the chemical milieu and physical forces experienced by cells within a 3D tissue are fundamentally different than those experienced by cells grown in monolayer culture. This has been shown to markedly impact cellular morphology and signaling. Several methods have been devised to generate 3D cell cultures including encapsulation of cells in collagen gels or in biomaterial scaffolds. Such methods, while useful, do not recapitulate the intimate direct cell-cell adhesion architecture found in normal tissues. Rather, they more closely approximate culture systems in which single cells are loosely dispersed within a 3D meshwork of ECM products. Here, we describe a simple method in which cells are placed in hanging drop culture and incubated under physiological conditions until they form true 3D spheroids in which cells are in direct contact with each other and with extracellular matrix components. The method requires no specialized equipment and can be adapted to include addition of any biological agent in very small quantities that may be of interest in elucidating effects on cell-cell or cell-ECM interaction. The method can also be used to co-culture two (or more) different cell populations so as to elucidate the role of cell-cell or cell-ECM interactions in specifying spatial relationships between cells. Cell-cell cohesion and cell-ECM adhesion are the cornerstones of studies of embryonic development, tumor-stromal cell interaction in malignant invasion, wound healing, and for applications to tissue engineering. This simple method will provide a means of generating tissue-like cellular aggregates for measurement of biomechanical properties or for molecular and biochemical analysis in a physiologically relevant model.
细胞间黏附与细胞-基质黏附的研究历来都是在附着于刚性基质的单层培养物上进行的。然而,组织中的细胞通常被包裹在紧密堆积的组织块中,在这个组织块中,细胞与许多相邻细胞以及细胞外基质成分建立了紧密的联系。因此,三维组织中的细胞所经历的化学环境和物理力与单层培养中的细胞所经历的化学环境和物理力有着根本的不同。这已被证明会显著影响细胞形态和信号传导。已经设计出了几种方法来生成三维细胞培养物,包括将细胞封装在胶原蛋白凝胶或生物材料支架中。这些方法虽然有用,但并不能重现正常组织中存在的紧密直接的细胞-细胞黏附结构。相反,它们更接近这样一种培养系统,即单个细胞松散地分散在细胞外基质产物的三维网络中。在这里,我们描述了一种简单的方法,将细胞置于悬滴培养中,并在生理条件下孵育,直到它们形成真正的三维球体,其中细胞彼此直接接触并与细胞外基质成分接触。该方法不需要专门的设备,并且可以进行调整,以包括添加任何可能对阐明对细胞-细胞或细胞-细胞外基质相互作用的影响感兴趣的极少量生物制剂。该方法还可用于共培养两种(或更多)不同的细胞群体,以阐明细胞-细胞或细胞-细胞外基质相互作用在确定细胞间空间关系中的作用。细胞间黏附与细胞-细胞外基质黏附是胚胎发育、恶性侵袭中肿瘤-基质细胞相互作用、伤口愈合以及组织工程应用等研究的基石。这种简单的方法将提供一种生成组织样细胞聚集体的手段,用于在生理相关模型中测量生物力学特性或进行分子和生化分析。