To date, only one study, conducted using a myocardial infarction mouse model, has investigated circFndc3b (mmu_circ_0 001113), demonstrating its cardioprotective effects.[22] Its human analog, hsa_circ_0 001361, has been shown to alleviate oxidative stress and regulate the NF‐κB pathway in osteoarthritis through the miR‐525‐5p/HO‐1 axis, thus safeguarding chondrocyte extracellular matrix integrity.[45] In our study, to elucidate the biological function of circFndc3b, a Cre‐LoxP‐based AAV‐shRNA system was utilized to selectively knock down microglia/macrophage's circFndc3b in the murine brain. This evidence concerns the gene HMOX1 and myocardial infarction.