Increase in plasma matrix metalloproteinase-9 in acute stroke patients with thrombolysis failure.

BACKGROUND AND PURPOSE: Platelet-rich thrombi are resistant to thrombolytics. Matrix metalloproteinases (MMPs) may be involved in platelet aggregation and contribute to thrombolysis failure in stroke patients. METHODS: Plasma samples from 23 stroke patients who had received thrombolytics and from 47 healthy volunteers were examined for MMP-2 and MMP-9 by both enzyme-linked immunosorbent assays and zymography. RESULTS: The arteries were recanalized in 15 patients but not in the other 8. The MMP-9 plasma level was significantly higher in patients whose arteries were not recanalized. CONCLUSIONS: MMP-9 may be associated with the formation of a thrombolytics-resistant thrombus.