gms | German Medical Science

Objective: Recently, the glymphatic system (GS) was discovered as a supposed perivascular pathway clearing the brain from solutes by convective transportation (Iliff JJ et al., 2012). Degradation products are transported along the cerebral arteries and veins to the cervical lymph nodes in a healthy organism. The impact of acute subarachnoid hemorrhage (SAH) on this important perivascular transport system is incompletely understood. Therefore we established a model for assessment of the glymphatic system in SAH and generated first data.

Methods: The cisterna magna injection model for SAH in a rat was used to assess glymphatic drainage properties. Application of the fluorescence marker Alexa 594 was followed by autologous blood injection. Brains were then harvested at three different time points (15 minutes, 1 hours, 4 hours), followed by cryofixation and separation into 10 µm brainslices. Visualization was achieved via anti-GFAP (astrocytes) and anti-von Willebrand factor (anti-vWF, endothel) stainings.

Results: As confirmed by our preliminary analysis, subarachnoidal injection of Alexa 594 resulted in fluorescent signals in the perivascular space in our model. Further analysis will define the exact location of Alexa 594 fluorescence in between the anti-GFAP- (astrocytic endfeet) and anti-vWF- (endothelial layer) positive signals. In addition, differences in the total area of Alexa 594 fluorescence in coronal brain sections in SAH animals compared with sham operated animals will be quantified.

Conclusion: Glmyphatic drainage may play an imminent role in SAH. Our animal model offers the possibility to analyze the impact of increased intracranial pressure and blood components on the glymphatic drainage. The glymphatic drainage during the acute phase after subarachnoid hemorrhage may be impaired independent of a mechanical blockage.