Fig. 2.

Micromanipulation of cellular function. a: Regulation of molecular signals (I) biochemical gradients generated from microfluidic devices influence cell polarization and migration; (II) the concentration level of growth factors secreted by cells depends on colony size and mediates the commitment of embryonic stem cells; (III) micropatterning controls cell–cell contact and distance; (IV) microfabricated devices regulate the distance and timing of cell–cell interaction. b: Regulation of Biomechanical signals (I) the control of cell shape regulates stem cell differentiation. Large substrate size leads to osteogenesis and small size adipogenesis; (II) substrate stiffness directs stem cell differentiation. High stiffness directs stem cells into osteoblasts, medium stiffness promotes myogenic differentiation, and low stiffness promotes neurogenesis. Only cancer cells can survive on an extreme soft substrate; (III) shape control of multicellular system affects local cell proliferation. High cell proliferation rates are in the regions with high mechanical stresses, such as edge of circles and corns of squares.