Abstract

Regenerative medicine is a process of replacing or regenerating human cells，tissues or organs to restore or establish their normal functions.One important approach is inductive tissue regeneration，which is defined as a technology to repair the tissues or organs using a bioactive matrix in situ.In this way，regeneration of tissues or organs can be achieved by recruitment of environmental matured cells and guided differentiation of stem cells.Therefore，one of the most important issues is to build up an in vivo microenvironment which can provide spatiotemporal signals to guide the adhesion，migration，proliferation，differentiation and apoptosis of cells at right locations and timing.Cells in a living body migrate in response to gradients of stimuli such as soluble chemoattractants（chemotaxis），surface-attached molecules （haptotaxis）and biophysical contact cues （durotaxis or mechanotaxis）.Gradients of attractive molecules could guide growing axons to their targets.In vivo gradients of chemical signals have been proved to exist and their roles in guiding the translocation of cells have been widely recognized.The introduction of so-called ‘gradient materials’，i.e.spatio-temporal gradients，offers a means to serve as an in vitro model，enabling the studies of cell behaviors in a complex but precisely defined microenvironment.The gradient materials have been used to study the cellular responses in terms of cell adhesion，distribution and alignment.Recently，cell migration on gradient materials and their potential applications in tissue regeneration have attracted more and more attention.In this chapter，we focus on the role of the gradient materials in guiding cell migration.Specific biological examples of gradients existing in vivo and the mechanism of induced cell migration will be summarized.Technologies for preparing the gradient materials will be introduced，followed by the migration behaviors of cells on the gradient materials.Finally，current challenges and future prospective are suggested.