W16 - Optimizing Xenon Microbubble Therapy for Neuroprotection in a Rat Model of Traumatic Brain Injury

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Ishaakannan Rajeshkannan

Undergraduate Researcher
New Jersey Institute of Technology Department of Biomedical Engineering
Edison, New Jersey, United States

Primary Investigator(s)

Rajarshi Chattaraj

Assistant Professor, Bio-Medical Engineering
New Jersey Institute of Technology
Springfield, New Jersey, United States

Co-Author(s)

YA

Yasmin Azem

PhD student
Njit, United States
WJ

Wafiza Julkipli

Research Assistant
New Jersey Institute of Technology, United States

Introduction: : Each year, approximately 69 million people suffer from traumatic brain injury (TBI), which is especially common among athletes, military personnel, and victims of falls or vehicle accidents. Despite its prevalence, effective pharmacological treatments remain inaccessible, and patients often suffer long-term cognitive, emotional, and physical impairments. Current treatment options for TBI are limited due to challenges in delivering therapeutics across the blood-brain barrier (BBB), a highly selective semipermeable border that regulates the movement of substances between the bloodstream and the central nervous system, serving as a protective barrier for the brain. Xenon gas has shown promise as a neuroprotective agent, protecting brain cells by calming overactive receptors and reducing harmful oxidative stress. By acting as a non-competitive antagonist at the glycine site on N-methyl-D-aspartate or NMDA receptors, xenon can reduce excitotoxicity, a process where excessive stimulation of neurons by neurotransmitters like glutamate leads to cell death. Inhalation-based delivery of xenon gas is impractical, limited by high costs and a lack of dosage control. This project aims to evaluate the effectiveness of xenon-loaded microbubbles, lipid-shelled microscopic bubbles filled with xenon, administered intravenously and directed to brain tissue using clinical ultrasound to rupture the bubbles near the carotid artery. This research not only contributes to the development of a non-invasive, targeted delivery system for mitigating TBI-induced neuropathology but also lays the groundwork for translational applications, given xenon’s FDA-approved status. The results will directly affect future long-term studies on xenon’s therapeutic mechanisms, with implications for broader neuroprotective strategies.

Materials and

Methods: : This study aims to evaluate the neuroprotective efficacy of xenon-loaded microbubbles (XeMBs) following TBI in a rat model. All animal protocols are approved by the Institutional Animal Care and Use Committee, and animals are anesthetized using isoflurane prior to all surgical procedures. First, moderate TBI will be induced using a fluid percussion injury system, which delivers a calibrated pressure pulse to the intact dura mater through a craniotomy, simulating a diffuse injury that has been shown to reliably produce blood-brain barrier disruption and glial activation. Following injury, animals are randomly assigned to different treatment groups. An optimal concentration of XeMBs will be used to treat the experimental group (n=5) via tail vein injection, while a control group (n=5) will receive a bolus injection of phosphate-buffered saline. This setup will help distinguish xenon’s specific contribution to neuroprotection. Behavioral outcomes will be assessed using three validated assays: the Open Field Test, Novel Object Recognition Test, and Elevated Plus Maze. These tests evaluate locomotor activity, memory, and anxiety-like behavior, which are affected by TBI. Seventy-two hours post-injury, animals will be sacrificed and undergo transcardial perfusion followed by brain extraction. Extracted brains will be fixed in 4% paraformaldehyde and cryosectioned using a cryostat. These sections will be subjected to immunohistochemistry targeting key markers of TBI-induced pathology: GFAP for reactive astrocytes and Iba1 for activated microglia. Wide-field fluorescence microscopy will be used for imaging, and quantitative analysis will be conducted using ImageJ software.

Results, Conclusions, and Discussions:: To evaluate the therapeutic potential of xenon microbubbles in treating traumatic brain injury, we conducted a series of histological and behavioral assessments across injury, sham, and treatment groups. Xenon microbubbles were clearly visible under ultrasound, confirming their presence in circulation and enabling targeted therapeutic delivery through focused ultrasound.

To evaluate behavioral outcomes following TBI, behavioral assays were conducted. The Open Field Test assesses general locomotor activity and anxiety-like behavior by tracking time spent in the center versus the outer zone of an open arena. Injured rats displayed higher movement levels than both sham and XeMB-treated rats, potentially indicating hyperactivity or stress-induced agitation. The Novel Object Recognition test evaluates recognition memory by measuring the time animals spend exploring a novel object versus a familiar one. Injured rats showed a marked preference for the old object zone, with significantly higher average speeds in that region, suggesting impaired memory and novelty recognition. In contrast, XeMB-treated rats exhibited more balanced speeds between zones, more closely resembling sham animals, indicating partial restoration of cognitive function. These results highlight XeMBs’ potential in mitigating behavioral and memory deficits associated with TBI.

Astrocytes and microglia, the brain’s resident glial cells, are key responders to traumatic brain injury. Astrocytes help maintain neuronal homeostasis and contribute to the blood-brain barrier. After TBI, they become reactive, showing increased branching and increased expression of GFAP, a hallmark of astrogliosis. Microglia, the CNS’s innate immune cells, also activate post-injury and are marked by elevated Iba1 expression and fewer branches, linked to membrane remodeling and phagocytosis. These markers provide critical insights into TBI pathology. This project addresses two critical unmet needs in TBI research: effective neuroprotection and practical therapeutic delivery. By transitioning from gaseous to injectable xenon, XeMBs represent a novel and non-invasive method for delivering neuroprotective treatment directly to injured brain regions. This research will not only advance our understanding of xenon’s therapeutic window but also contribute to the broader field of drug delivery across the blood-brain barrier, a fundamental obstacle in neurology, making this work relevant to scientists, pharmaceutical developers, and clinicians seeking efficient interventions for acute brain injuries.

Acknowledgements and/or References (Optional): : Acknowledgements: Dr. Rajarshi Chattaraj, Yasmin Azem, Wafiza Julkipli, Dr. Byan Pfister's Lab Team, Honors Summer Research Institute, 2025 Provost Undergraduate Research and Innovation Summer Fellowship

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