Vascular smooth muscle cells (VSMC) are important for contraction, blood flow distribution and regulation of blood vessel diameter, but to what extent they contribute to the integrity of blood vessels and blood-brain barrier function is less well understood. In this report, we explored the impact of the progressive loss of VSMC in the Notch3-/- mouse on blood vessel integrity in the central nervous system
Notch3 is necessary for blood vessel integrity in the central nervous system.
Age, Specimen part
View SamplesThe blood-brain barrier (BBB) consists of specific physical barriers, enzymes and transporters, which together maintain the necessary extracellular environment of the central nervous system (CNS). The main physical barrier is found in the CNS endothelial cell, and depends on continuous complexes of tight junctions combined with reduced vesicular transport. Other possible constituents of the BBB include extracellular matrix, astrocytes and pericytes, but the relative contribution of these different components to the BBB remains largely unknown. Here we demonstrate a direct role of pericytes at the BBB in vivo. Using a set of adult viable pericyte-deficient mouse mutants we show that pericyte deficiency increases the permeability of the BBB to water and a range of low-molecular-mass and high-molecular-mass tracers. The increased permeability occurs by endothelial transcytosis, a process that is rapidly arrested by the drug imatinib. Furthermore, we show that pericytes function at the BBB in at least two ways: by regulating BBB-specific gene expression patterns in endothelial cells, and by inducing polarization of astrocyte end-feet surrounding CNS blood vessels. Our results indicate a novel and critical role for pericytes in the integration of endothelial and astrocyte functions at the neurovascular unit, and in the regulation of the BBB.
Pericytes regulate the blood-brain barrier.
Sex, Age, Specimen part
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