Selective MMP-inhibition with Ro 28-2653 in acute experimental stroke – a magnetic resonance imaging efficacy study

Blood–brain-barrier (BBB) breakdown due to matrix metalloproteinase (MMP) activity following stroke is often associated with cerebral edema, larger infarct volumes and bad outcome. In the present study we examined a novel MMP-inhibitor (Ro 28-2653) with high selectivity for MMP2, MMP9 and membrane type 1-MMP in an acute stroke model comparing two different treatment regimens. We subjected rats to 90 min of focal cerebral ischemia followed by 3 days or 7 days of reperfusion, respectively, using the middle cerebral artery (MCA) filament occlusion technique. Ro 28-2653 was administered daily in a vehicle solution for 2 days or 6 days after ischemia, respectively. We assessed the behavior with a functional neuroscore and infarct volumes as well as blood–brain-barrier (BBB) breakdown with magnetic resonance imaging (MRI) after 3 and 7 days. Infarct edema volumes, BBB breakdown and behavior at 3 days were significantly attenuated in rats treated for 2 days with Ro 28-2653 as compared to vehicle and untreated controls. After 6 days of treatment however, infarct and BBB breakdown volumes as well as behavior did not differ significantly between the groups at 7 days. The new high selective MMP-inhibitor Ro 28-2653 significantly reduced brain injury only when administered in the first 2 days after focal cerebral ischemia. Prolonged treatment for 6 days did not show any beneficial effects possibly due to interference with protective restorative processes.

Research Highlights
► Oral application of Ro 28-2653 given for 2 days after focal cerebral ischemia and reperfusion exerts neuroprotective effects up to day 3 after ischemia as measured by MRI and a functional neuroscore.
► This effect could not be reproduced by prolonged treatment over 6 days at 7 days after ischemia. Although Ro 28-2653 did not increase mortality, it cannot be ruled out that side-effects, like impairment of mitochondrial function and increased apoptosis, are responsible for this loss of effect.
► In conclusion, prolonged inhibition of MMPs might interfere with protective restorative processes in the ischemic brain.