Defining One-Way Streets for Mammalian Cells

Tissues engineered in vitro can be used to restore and repair human tissues, potentially saving the lives of some patients waiting for organ donation. One major challenge in engineering complex tissues is directional control of cell movement. For example, different cell types assemble in specific patterns to form functional organs, capillaries sprout in the direction of new tissues or wounds, and neural cells migrate in specific directions during formation or regeneration of nervous systems. To date, the primary techniques for inducing cells to migrate into scaffolds rely on chemical cues released from bioactive materials. Coaxing cells to assemble into tissue patterns with dimensions ranging from micron to centimeter length scales remains a challenge. The groups of Prof. Ho and Prof. Co have reported recently a breakthrough in controlling cell migration that shatters all distance records over which cells can be guided directionally. Relying on their discovery of how mammalian cells sense and respond to the geometry of their environment, they demonstrated in Advanced Materials (2007) p1084, how cells can be coaxed like car drivers to follow arbitrary paths strictly in one direction. This discovery will have profound impact on the design of tissue scaffolds and change fundamentally studies of cell migration relevant in the progression of many diseases including arthritis and cancer.