Oral Presentation Matrix Biology Society of Australia and New Zealand Annual Meeting 2012

Perlecan Domain V IS NEUROPROTECTIVE AND NeuroregeneratiVE In MULTIPLE Ischemic Stroke Models (#28)

Michael P Kahle 1 , Jill Roberts 2 , Emma Gowing 3 , Andrew N Clarkson 4 5 , Gregory J Bix 2 4
  1. Molecular and Cellular Medicine, Texas A&M College of Medicine, College Station, Texas, USA
  2. Anatomy and Neurobiology, University of Kentucky College of Medicine, Sanders-Brown Centre for Aging, Lexington, Kentucky, USA
  3. Anatomy, University of Otago, Dunedin, New Zealand
  4. Neurology, University of Kentucky College of Medicine, Sanders-Brown Center for Aging, Lexington, Kentucky, USA
  5. Psychology, University of Otago, Dunedine, New Zealand

The role of the extracellular matrix in ischemic brain stroke is poorly understood. Indeed, its role has largely been relegated to that of a degradation by-product after stroke, and a marker of blood-brain barrier dysfunction. However, we have recently demonstrated that perlecan domain V (DV), a proteolytic fragment of the vascular basement membrane that is persistently generated after stroke, is neuroprotective, enhances angiogenic brain repair (in contrast to its previously characterized anti-angiogenic effect outside of the central nervous system), and inhibits chronic glial scar formation (a potential physical barrier to brain repair) when administered via intraperitoneal injection 24 hours post-stroke. Protection was observed in two distinct models of transient focal ischemia in mice and rats, the stereotactic injection of vasospasm-inducing endothelin-1 next to the middle cerebral artery (MCA) and the tandem ipsilateral common carotid artery and MCA occlusion model. This resulted in rapid functional recovery to pre-stroke levels in two days. Objectives: We now investigated whether DV could also be therapeutic in a permanent focal ischemia model in both young and aged (an important clinical factor as the elderly population is both more likely to suffer a stroke and potentially less well equipped to recover than younger stroke suffers) mice and whether it might enhance neurorepair by enhancing post-stroke neurogenesis, neuronal migration, and the number of these new born neurons that reach the infarct and peri-infarct sites and regenerate brain tissue. Methods and Results: We now report that DV treatment 6 hours after permanent focal ischemia in a mouse motor cortex photothrombotic stroke model was equally as neuroprotective inasmuch as ischemic lesions were significantly smaller in DV-treated animals (n=7 animals per group). Importantly, this was also the case for aged mice treated with DV. Furthermore, these animals had significantly improved post-stroke motor function as measured by the cylinder and grid-walking tests. Additionally, DV unexpectedly enhanced several aspects of post-stroke neuronal regeneration including increasing neurogenesis in the subventricular zone, migration towards the peri-infarct region and ischemic core, and repopulation and synaptic connection of these new neurons in the ischemic core. In vitro analysis demonstrated that DV significantly increased neurosphere size (neurogenesis) and enhanced cortical neuron migration via the alpha2beta1 integrin, a receptor that has not previously been implicated in neurogenesis, neuronal migration or synaptogenesis. Indeed, alpha2beta1 function blocking antibody prevented DV effects on neurons, and neurons isolated from alpha2 integrin-knockout animals were not affected by DV. Conclusions: Collectively, these results suggest that DV is equally effective in transient and permanent ischemic stroke models, effective in aged animals, and in addition to having significant positive post-stroke effects on existing neurons, astrocytes and neovasculature, also enhances neuronal regeneration of dead brain tissue, further supporting DV as a promising novel stroke therapy.