Zhou et al. (2021) found increased MMP-9 protein expression in cardiomyocytes of rats with pulmonary embolism, similar to our results. Additionally, a recent study revealed increased VCAM-1-mediated vascular inflammation in a mouse model of acute lung diseases (Kim et al., 2023). Hirudin inhibited up-regulation of VCAM, thereby inhibiting thrombus formation (Chen et al., 2001). This evidence concerns the gene MMP9 and pulmonary embolism.