A Controlled Mouse Model for Neonatal Polymicrobial Sepsis
January 27th, 2019
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This protocol provides the necessary steps to establish and evaluate neonatal sepsis in 7-day-old mice.
Overview
This protocol provides the necessary steps to establish and evaluate neonatal sepsis in 7-day-old mice. It details the preparation of a cecal slurry model for studying polymicrobial sepsis.
Key Study Components
Area of Science
- Neonatal sepsis
- Polymicrobial infection models
- Mouse models in biomedical research
Background
- The cecal slurry model is used to investigate neonatal pathophysiology.
- Humane endpoints in sepsis research are not well defined.
- Standardized procedures are crucial for reproducibility.
- Data-driven approaches help identify moribund pups early.
Purpose of Study
- To establish a reliable method for inducing sepsis in neonatal mice.
- To evaluate the effects of cecal slurry on neonatal health.
- To provide a protocol that minimizes variability in experimental outcomes.
Methods Used
- Preparation of cecal slurry from adult mice.
- Standardized injection protocols for neonatal mice.
- Use of sterile techniques to prevent contamination.
- Data analysis for determining lethal doses and outcomes.
Main Results
- Successful preparation of cecal slurry with consistent aerobic colony forming units.
- Establishment of a dose-dependent lethality in neonatal mice.
- Identification of moribund pups using a data-driven approach.
- Protocol allows for reproducible results across experiments.
Conclusions
- The cecal slurry model is effective for studying neonatal sepsis.
- Standardized methods enhance the reliability of research findings.
- Future studies can build on this protocol to explore neonatal health.
Frequently Asked Questions
What is the cecal slurry model?
The cecal slurry model is a method used to induce polymicrobial sepsis in experimental animals, particularly neonatal mice.
How is the cecal slurry prepared?
Cecal contents are pooled from adult mice, suspended in sterile dextrose water, and stored for later use.
What are the humane endpoints in this study?
Humane endpoints involve identifying moribund pups early to minimize suffering during experiments.
How do you determine the lethal dose for the slurry?
The lethal dose is determined through dose titration experiments for each new stock of cecal slurry.
What tools are necessary for the procedure?
Sterile dissection tools, centrifuge tubes, and a biological safety cabinet are essential for the procedure.
Can the cecal slurry be stored?
Yes, aliquots of cecal slurry can be stored at minus 80 degrees Celsius without losing aerobic colony forming units for up to six months.
Executive Industry Relevance
This standardized neonatal polymicrobial sepsis model enables reproducible preclinical evaluation of prophylactic or therapeutic interventions in a clinically relevant disease-relevant system. By defining objective, data-driven humane endpoints based on righting reflex and mobility, the model supports mechanistic de-risking and translational biomarker alignment in early discovery. The approach reduces variability between donors and improves predictive confidence for go/no-go decisions in sepsis-targeted drug development programs.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables therapeutic hypothesis interrogation in a neonatal sepsis context where pathophysiology differs from adult models.
- Operational Value: Provides a standardized, reproducible system for evaluating target engagement and pathway modulation.
- Strategic Value: Supports predictive confidence by linking functional readouts (righting, mobility) to survival outcomes.
Screening & Assay Development
- Scientific Value: Generates quantitative, time-resolved health scores that enable dose-response and intervention efficacy profiling.
- Operational Value: Uses weight- and litter-adjusted dosing with automated calculation tools to ensure consistency across experiments.
- Strategic Value: Facilitates high-fidelity compound screening by identifying moribund pups at earliest possible timepoint.
Translational & Preclinical Research
- Scientific Value: Models disease-relevant sepsis pathophysiology in neonatal mice, enabling continuity from discovery through preclinical validation.
- Operational Value: Defines humane endpoints using observable behaviors (righting within 4 seconds, mobility) that reduce subjectivity and improve inter-rater reliability (97% accuracy).
- Strategic Value: Supports risk-adjusted advancement decisions by separating survivor and non-survivor groups based on bilateral failure to right after 21 hours post-challenge.
Pipeline & Workflow Integration
The model fits within the discovery continuum from target validation to lead identification, providing a disease-relevant system for evaluating sepsis interventions before preclinical efficacy studies.
- Discovery Biology: Supports hypothesis testing of neonatal-specific immune and inflammatory pathways via polymicrobial challenge.
- Screening: Enables assay readiness through standardized cecal slurry preparation, filtration, and aliquoting for consistent pathogen load.
- Analytics: Delivers quantitative dependent variable measurements (health scores, survival, weight change) that allow teams to compare intervention effects across conditions.
- Translational Research: Connects to preclinical continuity through defined humane endpoints that mirror clinical deterioration and support biomarker-aligned monitoring.
- Enterprise Reuse: Cryopreserved cecal slurry stocks allow reuse across multiple litters and experiments over six months, reducing preparation variability.
Operational & Enterprise Impact
- Scientific Value: Reduction of mechanistic ambiguity through objective, behavior-based humane endpoint criteria.
- Operational Value: Standardization of slurry preparation, dosing, and monitoring minimizes experimental error and increases reproducibility.
- Strategic Value: Improved go/no-go decisions by identifying non-recovering animals earlier via failure to right on both sides after 21 hours.
- Portfolio Impact: Enables risk-adjusted prioritization of sepsis interventions based on survival separation in model.
Implementation Considerations
- Requires expertise in aseptic technique, neonatal mouse handling, and behavioral monitoring.
- Necessitates centrifugation, filtration, and cold storage infrastructure for slurry preparation and aliquoting.
- Demands cross-team standardization of health scoring criteria and monitoring intervals (e.g., 12–21 hr, 21–48 hr post-challenge).
- Requires adaptation of dose calculations based on litter weight and stock concentration, supported by provided spreadsheet tool.
- Practical limitation: Model variability necessitates dose titration for each new slurry stock to determine lethality in facility.
Biopharma FAQs
Why does failure to right within four seconds matter for target validation?
Failure to right within four seconds is a key behavioral metric used to assess neuromotor function and disease progression in neonatal sepsis. It enables objective stratification of pups into health categories that correlate with survival outcomes. This metric supports target validation by linking functional readouts to mechanistic disease modification.
How does isolating the independent variable (cecal slurry dose) fit the discovery pipeline?
The model uses weight- and litter-adjusted dosing to isolate cecal slurry concentration as the independent variable, enabling reproducible dose-response relationships. This standardization allows researchers to attribute changes in health scores or survival directly to the intervention being tested. Isolating the independent variable is essential for target validation and lead identification in early discovery.
What quantitative dependent variable measurements enable mechanistic de-risking?
Quantitative measurements include righting reflex latency, mobility scoring, survival time, and percent weight change over time. These outputs allow teams to compare intervention groups and assess biological activity with statistical rigor. The separation of survivor and non-survivor groups based on bilateral failure to right after 21 hours provides a robust, translatable endpoint for de-risking.
Why do replication requirements matter for cross-functional collaboration?
Replication ensures that health scoring (e.g., fail to right-nonmobile, rights-lethargic) is consistent across experimenters and sites, which is critical for multi-site preclinical programs. The protocol demonstrated 97% inter-rater reliability in behavioral classification when using trained observers. This consistency supports reliable data sharing between discovery, toxicology, and translational teams.
What statistical analysis capabilities are required before implementation?
Implementation requires the ability to perform dose titration to determine lethal dose (LD50 or equivalent) for each new cecal slurry stock. Teams must be capable of generating Kaplan-Meier survival curves and comparing health score distributions between groups. These analyses are necessary to establish model validity and support go/no-go decisions based on survival separation.
