TIMP4 and atrial fibrillation: Furthermore, the ADSC-exosomes alleviated cardiac fibrosis (Figure 6D), repressed left atrial diameter (Figure 6E), and alleviated apoptosis (Figure 6F) in the AF model, which were reversed by circFryl depletion, whereas TIMP4 overexpression and miR-338-3p inhibition abolished the effects of sicircFryl (Figure 6D–F).