Recent advances in the design of injectable hydrogels for stem cell-based therapy

Stem cell therapy holds promise for the treatment of many diseases but the efficacy is limited by the unfavorable environments in the impaired tissues. The use of hydrogel scaffolds has been proposed as a strategy to overcome this by improving the survival and engraftment of injected stem cells. In particular, injectable hydrogels are deemed highly attractive owing to their ease of use, shape adaptability and ability to access parts of the body that are difficult to reach. In this review, we provide an overview of the recent efforts in the design of various injectable hydrogels for stem cell-based tissue engineering. Herein, we first discuss the different aspects of hydrogels’ physical properties that can regulate stem cell behavior. In addition, we examine in detail the biomaterial (natural, synthetic or hybrid) composition and characteristics of hydrogel matrices used in regenerative medical applications involving stem cells. Lastly, we outline some representative next-generation hydrogel systems with additional features to potentially enhance the therapeutic efficacy and finally we provide a summary and outlook on developments in the field.