A High Output Method to Isolate Cerebral Pericytes from Mouse

In recent years, cerebral pericytes have become the focus of extensive research in vascular biology and pathology. The importance of pericytes in blood ...

Heidelberg University

To estimate changes in the (23)Na density and in the (23)Na relaxation time T(2) * in the anatomically small murine brain after stroke.

Chemical shift sodium imaging in a mouse model of thromboembolic stroke at 9.4 T.

A triple-resonant coil setup with an (1)H linear resonator and a double-tuned (23)Na/(35)Cl surface coil was used to study the evolution of T 2 (*) and M 0 for (35)Cl and (23)Na in a rat stroke model during the acute phase at 9.4 Tesla.

Chlorine and sodium chemical shift imaging during acute stroke in a rat model at 9.4 Tesla.

This study characterizes a new model of thromboembolic stroke of the middle cerebral artery in C57 black/6J mice, thus offering an opportunity to use the model for studying ischemic stroke in transgenic mice. Thromboembolic stroke was induced by local injection of either 1.5 or 3.0 UI of thrombin directly into the right MCA of C57 black/6J mice. Cerebral blood flow (CBF) velocity was measured continuously by laser Doppler flowmetry, which allowed documentation of both MCA occlusion and of spontaneous recanalization. After 24 h, all animals were euthanized. Cryosections were cut at 400-μm intervals and silver stained with the high-contrast method for volumetric assessment of infarct size. Interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), caspase-3 and hsp 70 protein levels were investigated by immunofluorescence. Thrombin injection resulted in clot formation in all animals. Cortical infarction occurred in 63% of the mice while 37% had a spontaneous MCA recanalization during the first 20 min following thrombin injection. In cases of successful MCA occlusion with consequent infarction, the clot was stable up to 2 h after formation. Subsequently, 20% recanalized spontaneously. Infarctions were restricted to the cortex with a mean lesion volume of 36 ± 5 for 1.5 UI and 56 ± 8 for 3.0 UI thrombin. Protein levels of IL-6, TNF-α, caspase-3, and hsp 70 were significantly increased after MCAO. The results demonstrate that the mouse thromboembolic stroke model produces cortical infarctions of consistent size in C57 black/6J mice, which is dependent upon the amount of thrombin used for clot formation. Spontaneous MCA recanalization occurs after 2 h of ischemia in 20% of mice. Thus, the thromboembolic model is an applicable stroke model for C57 black/6J mice, which mimics many of the features of human stroke, including spontaneous recanalization. However, strain differences between Swiss and C57 black/6J mice must be taken into account when using the model.

Characterization of a new model of thromboembolic stroke in C57 black/6J mice.

A recent study suggests that patients with persistent occlusion of the middle cerebral artery (MCA) following treatment with recombinant tissue plasminogen activator (rt-PA) have better outcomes than patients with MCA occlusion not receiving rt-PA. We performed a study to elucidate possible mechanisms of this finding in a new model of thromboembolic stroke closely mimicking human pathophysiology.

Pro-inflammatory mediators and apoptosis correlate to rt-PA response in a novel mouse model of thromboembolic stroke.

To evaluate potential scan time reduction in (23)Na-Magnetic Resonance Imaging with the chemical shift imaging sequence (CSI) using undersampled data of high-quality datasets, reconstructed with an iterative constrained reconstruction, compared to reduced resolution or reduced signal-to-noise ratio.

Scan time reduction in ²³Na-Magnetic Resonance Imaging using the chemical shift imaging sequence: Evaluation of an iterative reconstruction method.

Due to the lack of specific diagnostic markers, the diagnosis of cancer-related stroke strongly depends on its phenotype. Distinct DWI lesion patterns with involvement of multiple vascular territories have been reported repeatedly in cancer-related stroke but have not been addressed in detail in a selected cohort of prospectively recruited cancer patients with emphasis on hypercoagulable conditions.

DWI Lesion Patterns in Cancer-Related Stroke--Specifying the Phenotype.

Cerebral amyloid angiopathy (CAA) is characterized by vascular deposition of amyloid β (Aβ) with a higher incidence of cerebral microbleeds (cMBs) and spontaneous hemorrhage. Since statins are known for their benefit in vascular disease we tested for the effect on CAA.

Statin Therapy and the Development of Cerebral Amyloid Angiopathy--A Rodent in Vivo Approach.

Cerebral amyloid angiopathy (CAA) is characterized by extracellular deposition of amyloid β (Aβ) around cerebral arteries and capillaries and leads to an increased risk for vascular dementia, spontaneous lobar hemorrhage, convexal subarachnoid hemorrhage, and transient focal neurological episodes, which might be an indicator of imminent spontaneous intracerebral hemorrhage. In CAA cerebral microbleeds (cMBs) with a cortical/juxtacortical distribution are frequently observed in standard magnetic resonance imaging (MRI). In vivo MRI of transgenic mouse models of CAA may serve as a useful tool to investigate translational aspects of the disease.

Development of Cerebral Microbleeds in the APP23-Transgenic Mouse Model of Cerebral Amyloid Angiopathy-A 9.4 Tesla MRI Study.

Diffusion magnetic resonance imaging (MRI) is the current-state-of-the-art technique to clinically investigate acute (0-24 h) ischemic stroke tissue. However, reduced apparent diffusion coefficient (ADC)-considered a marker of tissue damage-was observed to reverse spontaneously during the subacute stroke phase (24-72 h) which means that low ADC cannot be used to reflect the damaged tissue after 24 h in experimental and clinical studies. One reason for the change in ADC is that ADC values drop with cytotoxic edema (acute phase) and rise when vasogenic edema begins (subacute phase). Recently, combined H- and Na-MRI was proposed as a more accurate approach to improve delineation between reversible (penumbra) and irreversible ischemic injury (core). The aim of this study was to investigate the effects of reperfusion on the ADC and the sodium MRI signal after experimental ischemic stroke in rats in well-defined areas of different viability levels of the cerebral lesion, i.e. core and penumbra as defined via perfusion and histology. Transient middle cerebral artery occlusion was induced in male rats by using the intraluminal filament technique. MRI sodium, perfusion and diffusion measurement was recorded before reperfusion, shortly after reperfusion and 24 h after reperfusion. The animals were reperfused after 90 min of ischemia.

Investigating potentially salvageable penumbra tissue in an in vivo model of transient ischemic stroke using sodium, diffusion, and perfusion magnetic resonance imaging.

The heart and brain are constantly interacting under normal physiological conditions. This interaction is under the control of the autonomic nervous system with parasympathetic and sympathetic nerve fibers including the participating brain structures. Pathological conditions, such as epilepsy and ischemic cerebral stroke influence heart function, especially the frequency and may result in severe arrhythmia. An asymmetric influence of the left and right brain hemispheres on the heart rate is still under debate. Conversely, the influence of the heart in cases of acute cardiac arrest on brain function is equally relevant and a common clinical problem after resuscitation. We review the damaging cascade of global cerebral hypoxia and the value of different diagnostic procedures as well as the ethical problem of the point in time of termination of consciousness and the instruments for estimating the prognosis.

[Interaction between heart and brain in sudden cardiac death].

In the field of experimental stem cell therapy, intra-arterial (IA) delivery yields the best results concerning, for example, migrated cell number at the targeted site. However, IA application also appears to be associated with increased mortality rates and infarction. Since many rodent studies systemically apply 1 × 10 cells, this could also be a consequence of engrafted cell number. The aim of this study was therefore to investigate the effect of different doses of adipose tissue-derived stem cells (ASCs) on engraftment rates and stroke outcome measured in vivo using 9.4-T high-field magnetic resonance imaging (MRI).

The effect of adipose tissue-derived stem cells in a middle cerebral artery occlusion stroke model depends on their engraftment rate.

Beyond the crucial role of apolipoprotein A-I (ApoA-I) on peripheral cholesterol metabolism, this apolipoprotein has also been implicated in beta amyloid (Aβ)-related neuropathologies. ApoA-I-Milano (M) is a mutated variant, which showed increased vasoprotective properties compared to ApoA-I-wild type in models of atherosclerosis and cardiovascular damage. We speculated that ApoA-I-M may also protect Aβ-affected vasculature and reverse some of the pathological features associated with Alzheimer's disease (AD). For this purpose, we produced and characterized human recombinant ApoA-I-wild type and ApoA-I-M proteins. Both of them were able to avoid the aggregation of Aβ in vitro, even though recombinant ApoA-I-M was significantly more effective in protecting endothelial cells from Aβ(1-42)-toxicity. Next, we determined the effect of chronic intravenous administration of rApoA-I-M in the APP23-transgenic mouse model of AD. We found reduced cerebral Aβ levels in mice that received rApoA-I-M, which were accompanied by a lower expression of astrocyte and microglia neuroinflammatory markers. Our results suggest an applicability of this molecule as a therapeutic candidate for protecting the brain in AD.

Intravenous treatment with human recombinant ApoA-I Milano reduces beta amyloid cerebral deposition in the APP23-transgenic mouse model of Alzheimer's disease.

The brain vasculature can be investigated in different ways ranging from in vivo to biochemical analysis. Immunohistochemistry is a simple and powerful technique that can also be applied to archival tissues. However, staining of brain vessels on paraffin sections has been challenging. In this study, we developed an optimized method that can be used in paraffin-embedded mouse and human brain tissues derived from healthy controls and neurological disorders such as Alzheimer's disease. We subsequently showed that this method is fully compatible with the detection of glial cells and key markers of Alzheimer's disease including amyloid beta and phosphorylated Tau protein. Furthermore, we observed that the length of microvasculature in hippocampus of TgCRND8 Alzheimer's disease mouse model is reduced, which is correlated with the decreased blood flow in hippocampus as determined by arterial spin labeling perfusion magnetic resonance imaging. Finally, we determined that the microvasculature length in two other Alzheimer's disease mouse models, APP and PS1 double-transgenic mice and P301S Tau-transgenic mice, is also shortened in the dentate gyrus. Thus, we have established a new, simple and robust method to characterize the brain vasculature in the mouse and human brain.

Analysis of the vasculature by immunohistochemistry in paraffin-embedded brains.

Sodium magnetic resonance (MR) imaging provides noninvasive insights to cellular processes by measuring tissue sodium concentration (TSC). Many clinical studies combine sodium MR imaging with clinical standard MR procedures, in which contrast media is frequently administered. This work investigates the influence of gadolinium-based contrast agents on quantification of TSC. Thus, either scan pauses between early and late contrast-enhanced acquisitions can be used efficiently or sodium imaging can be performed as the final scan after dynamic contrast-enhanced acquisition.

Marc Fatar

Department of Neurology,
Universitätsmedizin Mannheim,
Department of Neurology, Universitätsmedizin Mannheim

Heidelberg University

A High Output Method to Isolate Cerebral Pericytes from Mouse

Marc Fatar

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Neurology,Universitätsmedizin Mannheim,Department of Neurology, Universitätsmedizin Mannheim

Heidelberg University

A High Output Method to Isolate Cerebral Pericytes from Mouse

Department of Neurology,
Universitätsmedizin Mannheim,
Department of Neurology, Universitätsmedizin Mannheim