Name: Author Spotlight: Imaging Pericytes Post-Subarachnoid Hemorrhaging in Rodents
Uploaded: 2023-08-18T15:00:00
Description: Watch this Scientific Journal Video about Imaging Pericytes Post-Subarachnoid Hemorrhaging in Rodents at JoVE.com

The study was supported by grants from the National Natural Science Foundation of China (81960226,81760223); the Natural Science Foundation of Yunnan Province (202001AS070045,202301AY070001-011)

The experimental protocol was approved by the Animal Ethics and Use Committee of Kunming Medical University (kmmu20220945). Sprague-Dawley (SD) rats of both sexes, 300-350 g, were used for the present study.
1. Inducing the SAH model
<ol>
	<li>Anesthetize the rats using 2% isoflurane and 100% oxygen. Maintain anesthesia by supplying continuous inhalation anesthesia with isoflurane (1%-3%). Secure the rat&#39;s head using a stereotaxic apparatus (see Table of Material...

Visualization of Brain Pericyte Contractility Post-Subarachnoid Hemorrhage

<ol>
	<li>Dalkara, T., Gursoy-Ozdemir, Y., Yemisci, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain+microvascular+pericytes+in+health+and+disease.">Brain microvascular pericytes in health and disease.</a> Acta Neuropathologica. 122 (1), 1-9 (2011).</li><li>Dore-Duffy, P., Cleary, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology+and+properties+of+pericytes.">Morphology and properties of pericytes.</a> Methods in Molecular Biology (Clifton, N.J). 686, 49-68 (2011).</li><li>Peppiatt, C. M., Howarth, C., Mobbs, P., Attwell, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bidirectional+control+of+CNS+capillary+diameter+by+pericytes.">Bidirectional control of CNS capillary diameter by pericytes.</a> Nature. 443 (7112), 700-704 (2006).</li><li>Attwell, D., Mishra, A., Hall, C. N., O'Farrell, F. 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A., Couch, Y., Sutherland, B. A., Buchan, A. 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Developed are high-resolution confocal imaging techniques for visualizing vital brain pericytes, non-vital brain pericytes, and the microvasculature in brain slices. In acute rat brain slices, the process entails initial labeling of pericytes with TO-PRO-311, followed by microvascular endothelial cells with IB412; subsequently, identification of deceased pericytes is conducted using PI. This protocol is straightforward, reproducible, and highly applicable for functional res...

Brain pericytes, distinguished by their slender protuberances and protruding cell bodies, encircle the microcirculation1,2. While cerebral blood flow augmentation is predominantly driven by capillary dilation, smaller arteries exhibit slower rates of dilation3. Pericyte contractility exerts influence over capillary diameter and pericyte morphology, impacting vascular dynamics4. Contraction of brain pericytes leads to capillary constriction, and in pathological scenarios, excessive contraction may impede erythrocyte flow5. Various factors, including norepinephrine released from the locus coeruleus, can induce brain pericyte contraction within capillaries6. With a regulatory role in cerebral blood flow, pericytes exhibit 20-HETE synthesis, serving as an oxygen sensor during hyperoxia7. Oxidative-nitrative stress-triggered contraction of brain pericytes detrimentally affects capillaries5. Despite both in vivo and ex vivo investigations into brain pericyte contraction8, limited knowledge persists regarding the imaging of viable and non-viable brain pericytes within brain slices.
Crucially, post-tissue fixation imaging of brain pericytes compromises their vitality and subsequent contractility assessment. Moreover, in scenarios such as neurological disorders (e.g., subarachnoid hemorrhage - SAH), transgenic labeling of brain pericytes fails to differentiate between viable and non-viable pericytes, as confirmed by our preliminary SAH-induced brain pericyte death study9. 
To surmount these challenges, we employed TO-PRO-3 to label live pericytes, while deceased ones were stained with propidium iodide (PI). We used high-resolution confocal imaging technologies to visualize viable and non-viable brain pericytes in brain slices while preserving slice activity during imaging. This article aims to present a reproducible method for imaging viable and non-viable brain pericytes in brain slices, serving as a valuable tool to probe the impact of brain pericytes on cerebral microcirculation post SAH.

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imaging vital and non-vital brain pericytes in brain slices following subarachnoid hemorrhage

Pericytes are crucial mural cells situated within cerebral microcirculation, pivotal in actively modulating cerebral blood flow via contractility adjustments. Conventionally, their contractility is gauged by observing morphological shifts and nearby capillary diameter changes under specific circumstances. Yet, post-tissue fixation, evaluating vitality and ensuing pericyte contractility of imaged brain pericytes becomes compromised. Similarly, genetically labeling brain pericytes falls short in distinguishing between viable and non-viable pericytes, particularly in neurologic conditions like subarachnoid hemorrhage (SAH), where our preliminary investigation validates brain pericyte demise. A reliable protocol has been devised to surmount these constraints, enabling simultaneous fluorescent tagging of both functional and non-functional brain pericytes in brain sections. This labeling method allows high-resolution confocal microscope visualization, concurrently marking the brain slice microvasculature. This innovative protocol offers a means to appraise brain pericyte contractility, its impact on capillary diameter, and pericyte structure. Investigating brain pericyte contractility within the SAH context yields insightful comprehension of its effects on cerebral microcirculation.

Author Spotlight: Imaging Pericytes Post-Subarachnoid Hemorrhaging in Rodents 

Imaging Vital and Non-vital Brain Pericytes in Brain Slices following Subarachnoid Hemorrhage

Our study showed a significant increase in pericytes deaths. So starting at a sick horse after SAH, it demonstrated a positive correlation between the number of low vital parasites and the time elapsed after SAH. Imaging vital and the non-vital brain parasites in brain slices following SAH and the parasite isolation techniques, have advanced the research in my field.Currently, it's quite difficult to fully distinguish between dead parasites and dead endothelial cells. Our study find contraction-dependent apoptosis in parasites after SAH. We have developed a very reliable protocol, which enables the fluorescent labeling, both functional and a non-functional brain parasite in brain sections, and the same time.

Under normal physiological conditions, brain pericytes generally do not undergo cell death. Figure 6 illustrates this phenomenon, with yellow indicating the presence of vital brain pericytes; brain pericytes show no staining with PI, indicating their viability. To further investigate whether pericytes remain attached to the microvasculature following cell death, methods were employed in a SAH rat model, and subsequent imaging was conducted.
Methods for imaging bot...

Watch this Scientific Journal Video about Imaging Pericytes Post-Subarachnoid Hemorrhaging in Rodents at JoVE.com

The preliminary inquiry confirms that subarachnoid hemorrhage (SAH) causes brain pericyte demise. Evaluating pericyte contractility post-SAH requires differentiation between viable and non-viable brain pericytes. Hence, a procedure has been developed to label viable and non-viable brain pericytes concurrently in brain sections, facilitating observation using a high-resolution confocal microscope.