Inflammation-triggered dual release of nitroxide radical and growth factor from heparin mimicking hydrogel-tissue composite as cardiovascular implants for anti-coagulation, endothelialization, anti-inflammation, and anti-calcification

Cardiovascular implants made from heterogeneous tissues (HT) often clinically face premature failures such as thrombosis, inflammation, and calcification. Herein, we report a hydrogel-tissue composite exhibiting inflammation instructive release of multiple components towards preventing coagulation, promoting endothelial growth, and modulating reactive oxygen species (ROS) homeostasis. The hydrogel composed of MMP-responsive segment-crosslinked heparin mimicking polymer was loaded with a nitroxide radical via ROS cleavable boronic ester bonds and vascular endothelial growth factor (VEGF) via electrostatic attraction. Matrix metalloproteinase (MMP), which reportedly showed elevated expression in inflammation response to foreign implant degraded the hydrogel and led to the release of heparin mimicking polymer and VEGF, enhancing its anti-coagulation capacity and accelerating the growth of endothelial cells on it. In addition, the composite could sense oxidation biosignal present in the inflammation environment and subsequently release a ROS scavenger for auto-regulation of ROS balance. Subcutaneous implantation in mice suggested that the composite could steer the immune response toward an anti-inflammation state and subcutaneous implantation in rats suggested an anti-calcification effect of it. The enhanced hemocompatibility and endothelialization effects in vivo were further confirmed by the endovascular implantation of tissues via membrane-covered stent delivery. The current findings demonstrate that the incorporation of functional hydrogel into the tissue sophistically exploiting host response for controlled release of multiple active cargos is a feasible approach to boost the anticoagulant, endothelialization, anti-inflammatory, and anti-calcification functions of HT-based cardiovascular implants.