Synthetically programming natural cell–cell communication pathways for tissue engineering

Tissue patterning, the process of localizing different cell types to the right place, is critical for tissue function and thus a central goal for tissue engineering. Developing embryos employ diverse cell interaction-based mechanisms to robustly pattern tissues, such as specifying different regions of the central nervous system and aligning all the hair cells in the inner ear. These events range in lengthscale and must all be specified with cell-level precision, imposing challenges for recreating such patterns in vitro using conventional engineering approaches. Synthetic developmental biology as an emerging field provides a complementary approach for patterning tissues, by harnessing the molecular mechanisms used by natural tissues to program self-organizing behavior of the cells. Here we review advances in adapting these modules to program cells in culture. These modules could potentially be used for biomedical tissue engineering, as a complement to existing methods for generating morphologically complex multi-cell-type tissues in vitro.