Novel angiogenesis therapeutics by redox injectable hydrogel - Regulation of local nitric oxide generation for effective cardiovascular therapy.

Nitric oxide (NO) possesses various functions in cardiovascular diseases; however, due to an extremely short half-life and low bioavailability, its therapeutic application is limited. In inflamed tissues, overproduced reactive oxygen species (ROS) rapidly react with the endogenous NO, reducing its bioavailability. Here, we developed a controllable NO-releasing redox injectable hydrogel (NO-RIG) formed by the electrostatic crosslinking between the polyion complex flower-type micelles composing of functional polymers to scavenge overproduced ROS and regulate the local NO expression level simultaneously. After the intracardiac injection to mice, NO-RIG converted to gel via physiological temperature-responsive character, distributed homogeneously, and retained in the myocardial tissue for more than 10 d. Treatment with NO-RIG remarkably decreased the infarction size and improved the heart function after myocardial infarction when compared to control injectable hydrogels, such as a simple NO-releasing or ROS-scavenging injectable gels. We found that NO-RIG treatment significantly enhanced the angiogenesis and new blood vessels formation in mice through the regulation of the NO sustained release and redox equilibrium. NO-RIG presents high potential in preventing and treating cardiovascular diseases.