Peripheral blood levels of matrix metalloproteinase-9 predict lesion volume in acute stroke

Matrix metalloproteinases (MMPs) have been implicated to play an important role in the destruction of the extracellular matrix in diseases of the central nervous system. This study investigated whether the expression of one of these proteases, MMP-9 in blood, is related to the size of human brain infarcts assessed with magnetic resonance imaging. Consecutively, twenty-one acute stroke patients were included prospectively into our study. In blood samples drawn within 24 h after onset, MMP-9 RNA-expression and proteolytic-activity were analyzed by quantitative polymerase chain reaction and gelatin zymography, respectively. The ischemic lesion volumes in time to peak perfusion maps and diffusion weighted imaging were measured morphometrically. RNA-expression levels of MMP-9 in peripheral blood mononuclear cells (PBMCs) correlated with the brain infarct lesion (TTP-delay 4 s, r = -0.61, p = 0.007; TTP-delay 6 s: r = -0.58, p = 0.012; DWI r = -0.47; p = 0.047). Our preliminary results demonstrate that MMP-9 RNA is upregulated in PBMCs in proportion to ischemia. These findings suggest that MMP-9 might contribute to the manifestation of ischemic brain damage. Since MMP-9 is upregulated in acute ischemia inhibition of MMP-9 may represent a complementary treatment target in acute stroke therapy.