Matrix metalloproteinase-9 as a marker for acute ischemic stroke: a systematic review

Matrix metalloproteinase-9 (MMP-9) is a possible marker for acute ischemic stroke (AIS). In animal models of cerebral ischemia, MMP expression was significantly increased and was related to blood-brain barrier disruption, vasogenic edema formation, and hemorrhagic transformation. The definition of the exact role of MMPs after ischemic stroke will have important diagnostic implications for stroke and for the development of therapeutic strategies aimed at modulating MMPs. The objectives of the present study were to determine (1) whether MMP-9 is a possible marker for AIS; (2) whether MMP-9 levels correlate with infarct volume, stroke severity, or functional outcome; and (3) whether MMP-9 levels correlate with the development of hemorrhagic transformation after tissue plasminogen activator (t-PA) administration. The literature was searched using MEDLINE and EMBASE with no year restriction. All relevant reports were included. A total of 22 studies (3,289 patients) satisfied the inclusion criteria. Our review revealed that higher MMP-9 values were significantly correlated with larger infarct volume, severity of stroke, and worse functional outcome. There were significant differences in MMP-9 levels between patients with AIS and healthy control subjects. Moreover, MMP-9 was a predictor of the development of intracerebral hemorrhage in patients treated with thrombolytic therapy. MMP-9 level was significantly increased after stroke onset, with the level correlating with infarct volume, stroke severity, and functional outcome. MMP-9 is a possible marker for ongoing brain ischemia, as well as a predictor of hemorrhage in patients treated with t-PA.