Myocardial protection by nanomaterials formulated with CHIR99021 and FGF1

The mortality of patients suffering from acute myocardial infarction (AMI) is linearly related to the infarct size. As regeneration of cardiomyocytes from cardiac progenitor cells is minimal in the mammalian adult heart, we have explored a new therapeutic approach which leverages the capacity of nanomaterials to release chemicals over time to promote myocardial protection and infarct size reduction. Initial screening identified two chemicals, FGF1 and CHIR99021 (a Wnt1 agonist/GSK-3s antagonist) which synergistically enhance cardiomyocyte cell cycle in vitro. Poly-lactic-co-glycolic acid (PLGA) nanoparticles (NP) formulated with CHIR99021 and FGF1 (CHIR+FGF1-NPs) provided an effective slow release system for up to 4 weeks. Intramyocardial injection of CHIR+FGF1-NPs enabled myocardial protection via reducing infarct size by 20% to 30% in mouse or pig models of postinfarction LV remodeling. This LV structural improvement was accompanied by a significant preservation of cardiac contractile function. Further investigation revealed that CHIR+FGF1-NPs resulted in a significant reduction of cardiomyocyte apoptosis and increase of angiogenesis. Thus, using a combination of chemicals and a NP-based prolonged release system that work synergistically, this study demonstrates a novel therapy for LV infarct size reduction in hearts with acute myocardial infarction.