MMP9 and Cerebral ischemia: If so, MMP‐9 raises the permeability of BBB by degrading ECM so as to promote vasogenic cerebral edema, increase inflammatory cell infiltration, and promote inflammatory reaction and apoptosis, which aggravates cerebral ischemia/reperfusion (Fujimura et al., 1999; Kamada et al 2007; Reeves et al., 2003; Rosenberg et al., 1998).