Hydrogels as stents

Hydrogels have been considered one of the most promising materials for stents, that is, supportive devices that restore the normal physiological functioning of an obstructed passageway. Based on natural or synthetic polymers, those materials present distinctive swelling behavior, biocompatibility and great mechanical properties, which can be tuned to allow the stent to behave in a manner mechanically similar to the natural tissue. Besides that, the tunable biodegradation of hydrogels makes them a great option for bioresorbable stents, avoiding the need for surgical removal. When using hydrogel-based materials, the key challenge is to design a material that simultaneously combines all stents' requisites with the advantageous characteristics of a hydrogel, without compromising its mechanical properties. Hydrogel-based stents have been exploited mainly for urological, gastric, and cardiovascular pathologies and, in this chapter, the recent advances made in the field will be reviewed, highlighting the main advantages, drawbacks as well as the main challenges.