MMP9 and edema: As the main gelatinases, MMP-2 and MMP-9 can degrade the collagen IV and fibronectin in the basal lamina around capillaries, therefore, overexpression of MMP-2 and MMP-9 will lead to development of vasogenic brain edema (Asahi et al., 2001a,b; Ramos-Fernandez et al., 2011).