MMP9 and subarachnoid hemorrhage: In models of subarachnoid hemorrhage (SAH) (Pan et al., 2017), ischemic stroke (Deng et al., 2020), and traumatic brain injury (Main et al., 2018), CsA has been shown to have a protective effect on the BBB by inhibiting CypA/MMP9 pathway and improving neurocognitive function, which was also noted in our model.