PDCD4 and retinal ischemia: In a model of retinal ischemia/reperfusion injury, TNF-α stimulated extracellular vesicles miR-21-5p secreted by gingival mesenchymal stem cells (GMSCs) was found to convert microglia from the Iba-1+/CD86+ state to the Iba-1+/Arg-1+ state by combining with programmed cell death 4 (PDCD4) (Yu et al., 2022).