FGF2 and ischemia reperfusion injury: Cheng et al. further exploited these ROS-responsive PVA polymers to afford an epicardial patch, which sustainably and controllably released fibroblast growth factor-2 (FGF-2) in vitro in response to the H2O2 as well as improved its retention in the pericardial cavity in vivo via overproduced ROS following ischemia-reperfusion injury in mice.