Background: Even though advanced technologies for interventional coronary reperfusion after myocardial infarction have been developed, reperfusion leads to various forms of cell death and thus worsens cardiac functions. Ferroptosis, a novel regulated cell death characterized by iron overload and reactive oxygen species(ROS) accumulation, involved in myocardial ischemia/reperfusion(I/R) injury. However, the role of ferroptosis in ischemia phase and reperfusion phase remains unclear, and key regulatory mechanisms of ferroptosis still need further exploration in the context of myocardial I/R injury. Methods: Myocardial I/R injury database GSE160516 downloaded from the Gene Expression Omnibus (GEO) database and ferroptosis-related genes (FRGs) obtained from the FerrDb database ([https://www.zhounan.org/ferrdb](https://www.zhounan.org/ferrdb)) were used to screen differentially expressed ferroptosis-related genes(DEFRGs). To identify crucial hub gene involved in cardiomyocyte ferroptosis, LASSO regression and SVM-RFE Algorithms were used. Venous blood samples were collected from acute myocardial infarction (AMI) patients on the first day after admission and within 48 h after percutaneous coronary intervention (PCI) to explore CD44 expression and its correlation with prognostic indicators. Moreover, a AC16 cardiomyocyte oxygen-glucose deprivation/reoxygenation (OGD/R) model was performed to verify the expression of CD44 and the role of ferroptosis in ischemia phase and reperfusion phase. Loss -of-function approaches was conducted to understand the role of CD44 in ferroptosis and explore the mechanisms in myocardial I/R injury. Result: Trough integrated bioinformatics analysis, CD44 was identified as the hub gene of ferroptosis, and significantly upregulated in myocardial I/R injury. In AC16 OGD/R model, the mRNA and protein levels of CD44 were significantly upregulated during the reoxygenation phase, but not the hypoxia phase. AMI patients of post-PCI had higher serum CD44 expression compared to those who did not undergo percutaneous coronary intervention(PCI) and healthy individuals. Serum CD44 levels of post-PCI was closely correlated with adverse prognostic indicators of MI. In additional, we found that reoxygenation further induce the development of ferroptosis. Knockdown of CD44 markedly aggravate cardiomyocyte injury and induced ferroptosis by CD44/SLC7A11 axis. Conclusion: Our results uncover the cardioprotective role of CD44 by attenuating hypoxia/reoxygenation-induced ferroptosis and injury. Targeting CD44-intiated signaling may serve as a promising therapeutic target for myocardial I/R injury.
