Abstract 163: Delayed Administration of Perlecan Doman V Significantly Increases Neurogenesis and Improves Functional Outcome after Experimental Ischemic Stroke

Abstract

Stroke, a major cause of significant morbidity and death, has limited therapeutic options. To that end, our goal is to develop novel stroke therapies by exploiting the brain’s own neuroreparative potential. We have discovered that perlecan, a prominent brain extracellular matrix proteoglycan, is proteolyzed into the bioactive protein fragment domain V (DV) after experimental and human ischemic stroke. DV is both neuroprotective and pro-angiogenic. Furthermore, functional outcome can be significantly improved in rodents by administering DV 6-24 hours after experimental transient (distal MCA occlusion) or permanent (photothrombosis) stroke. Here we studied in mechanistic detail whether delayed DV administration (initiated 7 days post-stroke) could increase neurogenesis and improve functional outcome after mouse transient MCA occlusion. Delayed DV administration also served to minimize confounding neuroprotective and angiogenic effects which occur with acute DV therapy. After two doses of DV (post-stroke day 7 and 9), stroked 3-month old male C57BL6 mice had significant functional improvement (rotor rod) compared to vehicle treated stroke controls. Brain immunohistochemistry 21 days after stroke demonstrated that DV treated mice had significantly more cells that were positive for BrdU (a marker of cell division), doublecortin (DCX, a marker for immature neurons), and NeuN (another neuronal marker) in the infarct area. Furthermore, stereotactic brain injection (AP + 0.00, ML - 1.2, DV – 2.5) with alpha 2 integrin (a known neuronal DV receptor) function blocking antibody on post-stroke day 3 inhibited DV’s post-stroke neurogenic effects. These results suggest that delayed DV treatment after experimental stroke increases neurogenesis, increases the number of new neurons that reach stroked brain regions and survive there, and improves functional outcome through an alpha 2 integrin dependent mechanism. Importantly, as we are unaware of any other delayed treatment other than FLAME clinical trial (fluoxetine treatment initiated 5-10 days after stroke) that significantly improves functional outcome after stroke, our data further suggest the promise of DV as an effective stroke therapy.