miR-21 in cardiovascular disease: new insights and emerging therapeutic potential

Cardiovascular diseases (CVDs) remain a leading cause of morbidity and mortality worldwide. Among various molecular regulators, microRNAs (miRNAs), small noncoding RNAs averaging 18–24 nucleotides have emerged as key players in CVD pathophysiology. miR-21, particularly, has been widely studied due to its involvement in inflammation, fibrosis, and cardiomyocyte survival. While some studies highlight its cardioprotective functions, others suggest it may contribute to adverse remodeling and disease progression. This review critically examines the dual role of miR-21 in CVDs, exploring both supportive and conflicting evidence. Additionally, miR-21’s potential as a diagnostic biomarker and therapeutic target is discussed while outlining key challenges and future research directions for clinical translation.