Are micropatterned substrates for directed cell organization an effective method to create ordered 3D tissue...

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.