MMP 9-instructed assembly of bFGF nanofibers in ischemic myocardium to promote heart repair.

: The only effective treatment for myocardial infarction (MI) is the timely restoration of coronary blood flow in the infarcted area, but further reperfusion exacerbates myocardial injury and leads to distal coronary no-reflow, which affects patient prognosis. Angiogenesis could be an important therapeutic strategy for re-establishing the blood supply to save the ischemic myocardium after MI. Basic fibroblast growth factor () has been shown to promote angiogenesis. However, direct intravenous administration of is not a viable option given its poor half-life . : Herein, we developed a peptide Lys-Lys-Pro-Leu-Gly-Leu-Ala-Gly-Phe-Phe () to encapsulate to form and proposed an enzyme-instructed self-assembly (EISA) strategy to deliver and slowly release in the ischemic myocardium. : The exerted a stronger cardioprotective effect than free in a rat model of myocardial ischemia-reperfusion (MI/R). results revealed that the could be cleaved by matrix metallopeptidase 9 (MMP-9) to yield through amphipathic changes. experiments indicated that intravenous administration of could lead to their restructuring into and long term retention of in the ischemic myocardium of rat due to high expression of MMP-9 and assembly-induced retention (AIR) effect, respectively. Twenty-eight days after MI/R model establishment, treatment significantly reduced fibrosis and improved cardiac function of the rats. We predict that our strategy could be applied in clinic for MI treatment in the future.