Pietak A, McGregor A, Gauthier S, Oleschuk R, Waldman S D
Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada.
J Tissue Eng Regen Med. 2008 Oct;2(7):450-3. doi: 10.1002/term.114.
Tissue-engineered constructs grown in vitro tend to have random arrangements of cells and extracellular matrix (ECM) and much research effort is aimed at developing long-range organization in tissue-engineered constructs. Contact guidance, which utilizes substrates with topographical patterns of the scale of single cells (0.1-100 microm) to limit cell adhesion to specific locations and to influence cell shape and orientation, is one popular method which has been used to generate order in cell cultures. The use of contact guidance to generate three-dimensional (3D) order relies on the assumption that a newly forming cell or tissue layer will be guided by the organization of the previous layer, which has been organized by the patterned substrate. However, the ability for cellular patterns to be coupled through organized cell layers from a patterned substrate has not been effectively demonstrated. The results of this study demonstrate that, although the patterned substrate induces initial organization and polarization, this organization is not sustained in the successive cell/tissue layers that form above the initial cell layer. This finding suggests that cells must be in direct contact with the patterned substrate to maintain their polarization, orientation and positional organization. Therefore, contact guidance does not appear to be a promising technique to create ordered 3D tissue-engineered constructs. Alternative techniques, in particular those involving the application of mechanical, electrical or flow fields, may be more useful in sustaining organization in multilayered constructs as the organizational influence extends as a field into 3D space.
体外培养的组织工程构建体往往具有随机排列的细胞和细胞外基质（ECM），许多研究致力于在组织工程构建体中实现长程有序排列。接触导向是一种常用的方法，它利用具有单细胞尺度（0.1 - 100微米）地形图案的底物来限制细胞黏附于特定位置，并影响细胞形状和取向，从而在细胞培养中产生有序排列。利用接触导向来生成三维（3D）有序排列依赖于这样一种假设，即新形成的细胞或组织层将由前一层的组织引导，而前一层是由图案化底物组织而成的。然而，细胞图案通过来自图案化底物的有组织细胞层进行耦合的能力尚未得到有效证明。本研究结果表明，尽管图案化底物诱导了初始的组织和极化，但这种组织在初始细胞层上方形成的连续细胞/组织层中并未持续。这一发现表明，细胞必须与图案化底物直接接触才能维持其极化、取向和位置组织。因此，接触导向似乎不是创建有序3D组织工程构建体的一种有前景的技术。替代技术，特别是那些涉及施加机械、电场或流场的技术，可能在维持多层构建体的有序排列方面更有用，因为组织影响作为一个场扩展到3D空间中。
