Hyaluronan expression following middle cerebral artery occlusion in the rat.

Hyaluronic acid, a major component of the brain extracellular matrix, is a regulator of angiogenesis, cell differentiation and migration. We used the rat middle cerebral artery occlusion model to show hyaluronan accumulation in stroke-affected areas. Using reverse transcription-polymerase chain reaction and Western blotting we showed up-regulation of hyaluronidase-1 and 2 between 1 h and 21 days after stroke. Hyaluronidase-1 was up-regulated earlier than hyaluronidase-2. The hyaladherins, receptor for hyaluronan-mediated motility and CD44 were also increased after stroke. Using immunohistochemistry, we showed association of hyaluronidases 1/2 and hyaladherins with neurons in the infarcted and peri-infarcted regions and hyaluronidase-1 with microvessels. Hyaluronan synthesis and degradation in the stroke hemisphere might have an impact on neuronal survival, angiogenesis and general tissue remodelling after stroke.