MiR-19-loaded oxidative stress-relief microgels with immunomodulatory and regeneration functions to reduce cardiac remodeling after myocardial infarction

Regeneration therapeutic strategy by microRNAs for boosting cardiomyocyte proliferation in treating myocardial infarction (MI) has the challenges of efficient delivery, and toxicity and risk of sudden death. Herein, oxidative stress-relief microgels were developed for miR-19a/b delivery, modulation of inflammatory tissue microenvironment, promotion of cardiomyocyte proliferation, and maintenance of heart function post MI. The cholesterol-modified miR-19a/b was encapsulated into the cavity of β-cyclodextrin in selenoketal-containing microgels. The microgels could effectively scavenge typical reactive oxygen species (ROS), and down-regulate the intracellular ROS level and the levels of typical inflammatory factors. The microgels could improve the acute inflammatory microenvironment for better cardiomyocyte survival and cellular uptake of miR-19a/b, leading to significant promotion of cardiomyocyte proliferation <i>in vivo</i>. In the rat and minipig models of MI, the microgels most effectively inhibited the acute inflammatory response and reduced the cardiomyocytes apoptosis, resulting in a significant improvement of cardiac function and restriction of pathological remodeling post MI, and thereby best heart function revealed by echocardiography and histological analysis.