MMP9 and Stroke: Matrix metalloproteinase-9 activity elevates in the plasma and brains of stroke patients and is identified as a mediator of tight junction disruption associating with brain edema and hemorrhagic transformation (del Zoppo et al., 2007; Sandoval and Witt, 2008; Chen H.S. et al., 2015; Maestrini et al., 2020).