MICROFLOW · Molecular mechanisms of microvascular dysfunction following hemorrhagic stroke

Stroke kills over 300,000 European citizens each year. Among the various forms of stroke subarachnoid hemorrhage (SAH) has the highest mortality, the worst prognosis, and the least well understood pathophysiology. Recent studies from the applicant's laboratory suggest that disturbances of the cerebral microcirculation may play an important role for brain damage after SAH. So far, however, little to nothing is known about the cellular or molecular mechanisms leading to microvascular dysfunction (mvD) following SAH resulting in an absolute lack of diagnostic and therapeutic options for affected patients. Therefore the aim of the current program is to investigate morphology and function of the cerebral microcirculation after SAH, to determine the molecular mechanisms responsible for mvD, and to use this knowledge to develop novel biomarkers and therapeutic options for SAH patients. For this purpose we will subject mice expressing fluorescent proteins in specific cells of the cerebral microcirculation (endothelium, pericytes, smooth muscle cells) to SAH and assess the temporal profile of morphology and function of these cells in vivo by 2-photon microscopy. To investigate gene expression associated with mvD we will employ microdissection microscopy for the isolation of microvessels from tissue sections and a novel strategy designed to capture mRNAs from specific cell types from whole brain tissue by using the Cre-lox system together with a transgenic mouse expressing an affinity-tagged ribosomal protein (Ribotag technology). Cell specific mRNA will then be analyzed by microarray technology. Finally, a small inhibitory RNA/lentiviral approach will be used to assess the therapeutic potential of identified disease-associated genes.The proposed research program may therefore result in the identification of novel biomarkers for the diagnosis of mvD in patients and in the development of novel strategies for the treatment of patients suffering from SAH.