Synthetic hydrogels for controlled stem cell differentiation

Stem cells offer great promise for regenerative medicine because of their pluripotency and their ability for self-renewal; however, their use in clinical treatments requires knowledge of the cues that control stem cell fate in vivo, and the ability to recapitulate those cues in tissue-engineered systems to direct differentiation into desired cell types and tissues. Hydrogels formed from poly(ethylene glycol) (PEG) are useful as scaffolds for promoting stem cell growth and differentiation towards the formation of tissues. The mechanical and biochemical microenvironment of these PEG hydrogels can be modified in a variety of ways to control cellular functions that are important in determining and maintaining stem cell phenotype. In this review, recent advances in the synthesis and modification of PEG hydrogels will be presented, along with important physicochemical considerations in the design of these hydrogels to better mimic the stem cell microenvironment and direct stem cell differentiation.