Smart materials to regulate the fate of stem cells

Due to stem cells' capacity of self-renewal and differentiation into target cells under controlled conditions, stem cell therapy is becoming one of the most promising treatments for degenerative diseases. However, precise control of stem cell differentiation is the major obstacle for stem cell therapy. Smart materials, which are able to change their properties by dynamically and reversely responding to external stimulations, have been explored for guiding stem cell differentiation. We have reviewed applications of thermosensitive, electroactive, photo-responsive, thixotropic and pH-sensitive materials in regards to stem cell fate. For each type of smart material, we address the regulation functions through the altered properties, such as inherent stiffness, swelling and contraction, controlled release of biomolecules or specific cell-binding RGD peptides, and other factors. It is expected that these smart materials will be widely used in regenerative medicines and stem cell therapy but technical challenges remain to be addressed through collaboration between material scientists, bioengineers and stem cell biologists.