Control of Adult Stem Cell Function in Bioengineered Artificial Niches

Stem cells are characterized by their dual ability to self-renew and differentiate, yielding essentially unlimited numbers of progeny that can replenish tissues with either high turnover such as blood and skin or contribute to the regeneration of organs with less frequent remodeling such as muscle. In contrast to their embryonic counterparts, adult stem cells can only preserve their unique functions if they are in intimate contact with an instructive microenvironment, termed niche. Stem cells integrate a complex array of niche signals that regulate their fate, keeping them in a relatively quiescent state during homeostasis, or controlling their numbers via symmetric or asymmetric divisions in response to the regenerative demands of a tissue. This chapter provides an overview of the current state of knowledge of structural and functional hallmarks of mammalian stem cell niches and offers a perspective on how bioengineering principles could be used to deconstruct the niche and providing novel insights into the role of its specific components in the regulation of stem cell fate. Such "artificial niches" constitute powerful tools for elucidating stem cell regulatory mechanisms that should fuel the development of novel therapeutic strategies for tissue regeneration.