Dura Mater Of Mice Research Articles

Postmortem Human Dura Mater Cells Exhibit Phenotypic, Transcriptomic and Genetic Abnormalities that Impact their Use for Disease Modeling

Patient-derived cells hold great promise for precision medicine approaches in human health. Human dermal fibroblasts have been a major source of cells for reprogramming and differentiating into specific cell types for disease modeling. Postmortem human dura mater has been suggested as a primary source of fibroblasts for in vitro modeling of neurodegenerative diseases. Although fibroblast-like cells from human and mouse dura mater have been previously described, their utility for reprogramming and direct differentiation protocols has not been fully established. In this study, cells derived from postmortem dura mater are directly compared to those from dermal biopsies of living subjects. In two instances, we have isolated and compared dermal and dural cell lines from the same subject. Notably, striking differences were observed between cells of dermal and dural origin. Compared to dermal fibroblasts, postmortem dura mater-derived cells demonstrated different morphology, slower growth rates, and a higher rate of karyotype abnormality. Dura mater-derived cells also failed to express fibroblast protein markers. When dermal fibroblasts and dura mater-derived cells from the same subject were compared, they exhibited highly divergent gene expression profiles that suggest dura mater cells originated from a mixed mural lineage. Given their postmortem origin, somatic mutation signatures of dura mater-derived cells were assessed and suggest defective DNA damage repair. This study argues for rigorous karyotyping of postmortem derived cell lines and highlights limitations of postmortem human dura mater-derived cells for modeling normal biology or disease-associated pathobiology.Graphical abstract

Vascular Network Imaging on Whole‐Mount Mouse Dura Mater with Cranial Bone

Intracranial vascular networks including both blood and lymphatic vessels are essential for the brain homeostasis and may change in structure or density under pathological conditions. Investigations on intracranial vascular networks require vasculature integrity in prepared samples. In the present study, we have established a method for acquiring vascular network images on a whole-mount mouse dura mater with cranial bone. Intracardial perfusion on sacrificed six-week-old mice was carried out with fluorescently tagged soybean agglutinin (SBA) and anti-LYVE-1 antibody labeling blood and lymphatic vessel respectively. Following dissection and fixation, the dura mater with the skull was mounted on a cover glass. A series of individual images at 512 x 512 pixels were taken under a confocal microscope for subsequent generation of the whole-mount mosaic image. For images at 20x magnification, 224 individual images were needed to cover the whole sample, including frontal and parietal areas, coronal suture, transverse and sagittal sinuses. For the 4x magnification, 12 images were required to cover the same sample area. Images at higher magnification revealed more clear and precise vascular network structural details. This method is useful in studying the relationship between the structural status of intracranial vascular networks and neurological disorders.

Histological investigations on the dura mater vascular system of mice

The human dura mater encephali is a well innervated and vascularized membrane. Its vascular system plays a crucial role in disorders and pathological cases like dural hematoma, meningitis, and different headache types. To investigate these diseases mouse models are increasingly being used. However, the literature on the vascular system of the mouse dura mater is sparse and explicit studies concerned exclusively with its vasculature are lacking. Here we present a detailed light and scanning electron microscopic investigation of the supratentorial dura mater of the mouse species, with a focus on the largest part of it, the parietal dura mater. By utilizing different immunohistochemical and classical staining methods, a “cartography” of the vascular system was achieved. Additionally, the different blood vessel types with their mural cells were characterized. In contrast to humans, no arteries were found in the mouse parietal dura mater. Its supply is assured through frontolateral and occipital localized arteriolar branches. These arteriolar vessels exhibit in some specimens arteriolar anastomoses with one another. The venous blood is drained to the superior sagittal and transverse sinus through satellite venules accompanying the arterioles or through solitary venules. In all samples, large ruptured venules were identified in the frontolateral dural area. Scanning electron microscopy revealed that these vessels were ruptured on the dorsal side (skull bones-oriented side) of the dura. Our results contribute to the anatomical data on the mouse species and may set up a basis for fundamental investigation of disorders, for which the role of dural blood vessels is not yet clarified.

Activation of 5-HT2B-receptors leads to increased vasodilation in mouse dura mater blood vessels

Neurogenic inflammation occurring in migraine may be associated with plasma protein extravasation (PPE) and vasodilation of dural blood vessels. 5-HT2B receptors may be involved in the onset of migraine attacks, in which receptor activation may induce increased synthesis of nitric oxide and, subsequently, the release of vasoactive CGRP from trigeminal nerve fibres. We found that the activation of 5-HT2B receptors in mice that were kept under hypoxic conditions for several weeks triggered an increased PPE in the dura mater. In addition to the PPE we now asked whether the activation of the 5-HT2B receptors also results in the vasodilation of dural blood vessels. For this purpose we combined intravital microscopy with the hypoxic mouse model. We removed a part of the skull in anesthetized mice and exposed the dura mater. Changes in blood vessel diameter have been observed via intravital microscopy after a topical application of substances directly onto the dura mater. Application of a 5-HT2B receptor agonist led to increased vasodilation of dural blood vessels. The effect could be completely blocked by specific receptor antagonists. The results confirm the involvement of 5-HT2B receptors in the onset of migraine attacks. While the topical application of CGRP alone was not sufficient to induce similar vasodilation in the mouse dura mater, the effect occurred when CGRP was applied after a preconstriction of the blood vessels by endothelin 1 (ET-1). Thus, we showed that the activation of 5-HT2B receptors not only induces PPE, but also dilates blood vessels in the dura mater. Whether and to which extent the vasodilation induced by 5-HT2B receptor activation is associated with the subsequent release of CGRP is subject to further studies.

Activation of 5-HT2B-receptors leads to increased vasodilation in mouse dura mater blood vessels

Activation of 5-HT2B-receptors leads to increased vasodilation in mouse dura mater blood vessels

Novel Characterization of Monocyte-Derived Cell Populations in the Meninges and Choroid Plexus and Their Rates of Replenishment in Bone Marrow Chimeric Mice

The mouse dura mater, pia mater, and choroid plexus contain resident macrophages and dendritic cells (DCs). These cells participate in immune surveillance, phagocytosis of cellular debris, uptake of antigens from the surrounding cerebrospinal fluid and immune regulation in many pathologic processes. We used Cx3cr1 knock-in, CD11c-eYFP transgenic and bone marrow chimeric mice to characterize the phenotype, density and replenishment rate of monocyte-derived cells in the meninges and choroid plexus and to assess the role of the chemokine receptor CX3CR1 on their number and tissue distribution. Iba-1 major histocompatibility complex (MHC) Class II CD169 CD68 macrophages and CD11c putative DCs were identified in meningeal and choroid plexus whole mounts. Comparison of homozygous and heterozygous Cx3cr1 mice did not reveal CX3CR1-dependancy on density, distribution or phenotype of monocyte-derived cells. In turnover studies, wild type lethally irradiated mice were reconstituted with Cx3cr1/-positive bone marrow and were analyzed at 3 days, 1, 2, 4 and 8 weeks after transplantation. There was a rapid replenishment of CX3CR1-positive cells in the dura mater (at 4 weeks) and the choroid plexus was fully reconstituted by 8 weeks. These data provide the foundation for future studies on the role of resident macrophages and DCs in conditions such as meningitis, autoimmune inflammatory disease and in therapies involving irradiation and hematopoietic or stem cell transplantation.

Stress-induced dura vascular permeability does not develop in mast cell-deficient and neurokinin-1 receptor knockout mice

Migraine headaches are often precipitated by stress and seem to involve neurogenic inflammation (NI) of the dura mater associated with the sensation of throbbing pain. Trigeminal nerve stimulation had been reported to activate rat dura mast cells and increase vascular permeability, effects inhibited by neonatal pretreatment with capsaicin implicating sensory neuropeptides, such as substance P (SP). The aim of the present study was to investigate NI, assessed by extravasation of 99-Technetium-gluceptate ( 99Tc-G), as well as the role of mast cells, SP and its receptor (NK-1R) in dura mater of mice in response to acute stress. Restraint stress for thirty min significantly increased 99Tc-G extravasation in the dura mater of C57BL mice. This effect was absent in W/W v mast cell-deficient mice and NK-1 receptor knockout mice (NK-1R−/−), but was unaltered in SP knockout mice (SP−/−). Acute restraint stress also resulted in increased dura mast cell activation in C57BL mice, but not in NK-1R−/− mice. These data demonstrate for the first time that acute stress triggers NI and mast cell activation in mouse dura mater through the activation of NK-1 receptors. The fact that SP−/− mice had intact vascular permeability response to stress indicates that some other NK-1 receptor agonist may substitute for SP. These results may help explain initial events in pathogenesis of stress-induced migraines.