# Role of Microglial Calcium Waves in Ischemic Stroke

> **NIH NIH R21** · UNIVERSITY OF VIRGINIA · 2022 · $161,500

## Abstract

Abstract
Ischemic stroke is a leading cause of death and severe disability in US and worldwide. Stroke-induced hypoxia
promotes a cascade of pathophysiological responses that lead to necrosis in the ischemic core, and apoptosis
in the hypo-perfused tissue known as penumbra. Cell death triggers an inflammatory response that contributes
to secondary injury and potentially harms the neurons surviving the initial insult. Microglia are the principal
immune cells in the brain parenchyma but their specific roles in secondary injury and the underlying mechanisms
of induction remain unclear. We hypothesize that increased calcium signaling is a key mechanism in the acute
stroke-induced microglial activation, possibly leading to increased release of proinflammatory cytokines. We
have developed a mouse reporter that indicates intracellular calcium in microglial cells. In this system, we use
2- photon imaging and middle cerebral artery occlusion (MCAo) to study microglial responses to ischemic injury
in vivo. We have demonstrated periodical waves of calcium activity in cortical microglia following intraarterial
occlusion, consistent with patterns of cortical spreading depolarizations (CSD). We propose to test the role of
these calcium transients by pharmacological inhibition of calcium influx, mediated by the calcium release-
activated calcium (CRAC) channels, and by genetic ablation of CRAC channel subunits. In Aim 1, we will directly
test whether the novel CRAC channel inhibitors developed by CalciMedica can reduce microglial activation,
neuro-inflammation and ultimately infarct size in the mouse model of MCAo. Pharmacological effects of these
blockers will be characterized with 2-photon imaging and their immune-protective effects in vivo will be evaluated
by cytokine profiling. In Aim2, the CRAC channel subunits Stim1 and Stim2 will be genetically ablated in brain
microglia and behavioral outcomes and infarct size after MCAo stroke will be evaluated. Stroke kills almost
130,000 Americans each year. If successful, clinical translation of this approach could help to reduce the burden
of this disease. Our overreaching objective is to apply the tools and techniques assembled under this pilot study
to a broader R01 project investigating CRAC-mediated calcium overload in all other brain cells during ischemic
injury.

## Key facts

- **NIH application ID:** 10418797
- **Project number:** 5R21NS116431-02
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **Principal Investigator:** Petr Tvrdik
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $161,500
- **Award type:** 5
- **Project period:** 2021-07-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10418797

## Citation

> US National Institutes of Health, RePORTER application 10418797, Role of Microglial Calcium Waves in Ischemic Stroke (5R21NS116431-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10418797. Licensed CC0.

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