The pivotal role of astrocytes in an in vitro stroke model of the blood-brain barrier.
Stabilization of the blood-brain barrier during and after stroke can lead to less adverse outcome. For elucidation of underlying mechanisms and development of novel therapeutic strategies validated in vitro disease models of the blood-brain barrier could be very helpful. To mimic in vitro stroke conditions we have established a blood-brain barrier in vitro model based on mouse cell line cerebEND and applied oxygen/glucose deprivation (OGD). The role of astrocytes in this disease model was investigated by using cell line C6. Transwell studies pointed out that addition of astrocytes during OGD increased the barrier damage significantly in comparison to the endothelial monoculture shown by changes of transendothelial electrical resistance as well as fluorescein permeability data. Analysis on mRNA and protein levels by qPCR, western blotting and immunofluorescence microscopy of tight junction molecules claudin-3,-5,-12, occludin and ZO-1 revealed that their regulation and localisation is associated with the functional barrier breakdown. Furthermore, soluble factors of astrocytes, OGD and their combination were able to induce changes of functionality and expression of ABC-transporters Abcb1a (P-gp), Abcg2 (bcrp), and Abcc4 (mrp4). Moreover, the expression of proteases (matrixmetalloproteinases MMP-2, MMP-3, MMP-9, and t-PA) as well as of their endogenous inhibitors (TIMP-1, TIMP-3, PAI-1) was altered by astrocyte factors and OGD which resulted in significant changes of total MMP and t-PA activity. Morphological rearrangements induced by OGD and treatment with astrocyte factors were confirmed at a nanometer scale using atomic force microscopy. In conclusion, astrocytes play a major role in blood-brain barrier breakdown during OGD in vitro.
Department of Pharmaceutical Chemistry, University of Vienna Vienna, Austria ; Department of Anesthesia and Critical Care, University Hospital Würzburg Würzburg, Germany.
Winfried
W
Neuhaus
Department of Anesthesia and Critical Care, University Hospital Würzburg Würzburg, Germany.
Fabian
F
Gaiser
Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg Heidelberg, Germany.
Anne
A
Mahringer
Serend-ip GmbH, Centre for Nanotechnology Münster, Germany.
Jonas
J
Franz
Serend-ip GmbH, Centre for Nanotechnology Münster, Germany.
Christoph
C
Riethmüller
Department of Anesthesia and Critical Care, University Hospital Würzburg Würzburg, Germany.
Carola
C
Förster
C6; blood-brain barrier; cerebEND; in vitro; ischemia; oxygen/glucose deprivation; stroke; traumatic brain injury