Brain Death Induction in Mice Using Intra-Arterial Blood Pressure Monitoring and Ventilation via Tracheostomy
April 17th, 2020
We present a murine model of brain death induction in order to evaluate the influence of its pathophysiological effects on organs as well as on consecutive grafts in the context of solid organ transplantation.
Although donation after donor brain death is the main source for solid-organ transplantation, the irreversible loss of brain function induces pathophysiological changes that lead to a systemic inflammatory response. This murine model of brain-death induction allows the use of a large variety of analytical tools and knockout models to study the pathways of brain-death regulation. For arterial catheterization after confirming a lack of response to pedal reflex and removing the upper abdominal hair, disinfect the exposed skin with 70%ethanol and use dissecting scissors to make a midline incision in the skin.
Using forceps, blunt dissect the submandibular glands and neck muscle tissue and separate the tissues to expose the common carotid artery. Place three 8-0 silk ligatures beneath the right common carotid artery and place a clamp on the proximal ligature. Bring tension in the artery so that the flow is suspended and close the most distal ligature.
Insert a 26-gauge arterial catheter through a small preformed skin hole on the cranial aspect of the incision. Squeeze the catheter with the forceps if the lumen is too large to reduce the backflow and secure the catheter with all three sutures, then use a single 5-0 monofilament nonabsorbable to fix the catheter to the skin near the preformed skin hole. To perform a tracheostomy, use forceps to blunt dissect the pretracheal musculature and place two 8-0 silk ligatures beneath the trachea.
Insert the ventilation tube between two tracheal cartilages to avoid unilateral ventilation and secure the tube with both prepared ligatures, then close the skin with a 6-0 monofilament nonabsorbable running suture and ventilate the mouse with a frequency of 150 per minute and a tidal volume of 200 microliters. To induce brain death in the experimental animal, arrange the mouse to the prone position and, holding the skin with forceps, use surgical scissors to remove the skin from the skull. Drill a one-millimeter caliper borehole perimedially above the left parietal cortex and use blunt forceps to penetrate the final tissue bridge of the skull.
After removing any sharp edges, insert a balloon catheter prefilled with saline with all of the air evacuated. When the catheter is entirely within the cranial cavity, use a syringe pump to begin inflating the catheter at approximately 0.1 millimeters per minute over a period of 10 to 15 minutes. When brain death occurs, stop the inflation of the balloon catheter and place a heating blanket over the mouse to avoid hypothermia.
After brain death has been confirmed, monitor and document the blood pressure regularly, infusing 100 microliters of saline every 30 minutes to stabilize the blood pressure of the animal. After four hours of brain death, exclude any animals without beating hearts and harvest the mouse organs and tissues of interest according to standard protocols. After brain-death induction, the blood pressure exhibits an initial hypertensive peak followed by a prolonged hypotensive phase.
Another well-established observation is that brain-death induction leads to activation of the immune system. Indeed, after four hours of brain death in this model, an organ-specific upregulation of immune markers is observed at the mRNA level. After a predefined period of brain death, the organs may be harvested for their direct analysis or for subsequent organ transplantation.
This model will enable in-depth studies into the influence of brain-death induced injury and has already revealed new insights into complement activation and leukocyte migration.
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Overview
This study presents a murine model for the induction of brain death to investigate the resulting pathophysiological effects on organs, particularly within the context of solid organ transplantation. The model allows for an analysis of the systemic inflammatory response and the subsequent impact on potential grafts.
Key Study Components
Area of Science
- Neuroscience
- Transplantation Biology
- Pathophysiology
Background
- Brain death is a critical factor influencing organ viability for transplantation.
- Loss of brain function triggers a systemic inflammatory response that can affect organ function.
- Understanding these changes is essential to improve transplant outcomes.
- The murine model serves as a platform for exploring specific pathways of brain-death regulation.
Purpose of Study
- To evaluate the organ-specific pathophysiological changes following brain death induction.
- To assess the consequences of these changes on organ transplantation potential.
- To gain insights into immune responses associated with brain death.
Methods Used
- The primary platform involves a murine model of brain death induction.
- Arterial catheterization and tracheostomy procedures are conducted to monitor and stabilize the animals.
- Brain death is induced using a balloon catheter inserted into the cranial cavity.
- The model facilitates studying immune marker upregulation at the mRNA level after brain death.
- The timeline involves monitoring blood pressure and organ harvesting after a defined period post-brain death induction.
Main Results
- The study found that brain death induction led to an initial hypertensive peak followed by prolonged hypotension.
- There was a significant upregulation of immune markers in a disease-specific manner following brain death.
- The model revealed insights into inflammation and immune activation, crucial for the understanding of organ viability post-transplant.
- After brain death, organs may be analyzed directly or used for transplantation, providing key insights into graft outcomes.
Conclusions
- This study demonstrates a practical model to explore the implications of brain death on organ function and transplantation.
- The findings contribute to understanding the immunological alterations associated with brain death.
- The research has significant implications for improving outcomes in organ transplantation by elucidating the pathophysiological effects of brain death.
Frequently Asked Questions
Executive Industry Relevance
This murine brain death model enables systematic investigation of pathophysiological changes that impact organ viability in transplantation, addressing a critical gap in preclinical models for studying donor-derived injury. By capturing hemodynamic instability and immune activation following brain death, the model supports mechanistic de-risking of graft failure pathways and informs strategies for organ preconditioning. Its compatibility with genetic and analytical tools enhances target validation and translational biomarker discovery in transplant immunology.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses related to brain death-induced inflammatory pathways and immune activation in donor organs.
- Operational Value: Supports functional target validation through measurable hemodynamic and mRNA-based immune marker changes post-induction.
- Predictive Value: Facilitates preclinical assessment of interventions aimed at mitigating brain death-related graft injury.
Screening & Assay Development
- Scientific Value: Provides a reproducible system for quantifying organ-specific immune marker upregulation at the mRNA level as a biomarker of brain death injury.
- Operational Value: Standardizes blood pressure monitoring and ventilation parameters to ensure consistent model induction across experiments.
- Assay Readiness: Enables preparation of donor organs for downstream functional analysis or transplantation testing under controlled brain death conditions.
Translational & Preclinical Research
- Scientific Value: Models disease-relevant systemic inflammatory response and complement activation observed in human brain death, supporting translational continuity.
- Operational Value: Allows longitudinal monitoring of graft viability parameters over a defined four-hour post-induction window.
- Risk Mitigation: Supports predictive confidence in evaluating organ preconditioning strategies before transplantation.
Pipeline & Workflow Integration
The model fits within the discovery-to-translational continuum by enabling early-stage mechanistic insight into donor-derived organ injury, informing lead identification for protective interventions, and supporting preclinical validation of graft preservation strategies.
- Discovery Biology: Facilitates hypothesis testing of brain death-regulated pathways using knockout models and pharmacological tools.
- Screening: Delivers standardized, quantifiable outputs including blood pressure trajectories and immune gene expression profiles.
- Analytics: Generates mRNA-level immune marker data and hemodynamic readouts that allow comparative analysis across experimental conditions.
- Translational Research: Connects mechanistic findings in mice to human transplant relevance through conserved inflammatory responses.
- Enterprise Reuse: Establishes a reusable platform for evaluating multiple therapeutic targets or preservation solutions in a controlled brain death setting.
Operational & Enterprise Impact
- Scientific Value: Reduces mechanistic ambiguity in brain death-induced organ injury by enabling causal pathway analysis.
- Operational Value: Ensures reproducibility through standardized surgical, ventilation, and monitoring protocols.
- Strategic Value: Improves go/no-go decisions in transplant research by quantifying biological risk associated with donor brain death.
- Portfolio Impact: Informs risk-adjusted prioritization of organ preservation or immunomodulatory candidates based on mechanistic de-risking data.
Implementation Considerations
- Requires expertise in microsurgical techniques including arterial catheterization, tracheostomy, and cranial burr hole placement.
- Dependent on precision instrumentation such as syringe pumps for controlled balloon inflation and hemodynamic monitoring systems.
- Necessitates cross-team standardization of brain death confirmation criteria and organ harvesting timelines.
- Must account for inter-animal variability in hemodynamic response and immune activation kinetics.
- Limited to murine physiology; findings require validation in larger preclinical models before translational extrapolation.
