Use of a Hanging-weight System for Liver Ischemia in Mice
August 7th, 2012
We established a novel murine model of a hanging weight system for portal triad occlusion. This technique may be useful for future investigations of ischemia in murine hepatic models.
The aim of this procedure is to induce liver ischemia for the study of reperfusion injury. This is accomplished by first exposing the lobes of the liver. The next step is to expose the left liver triad, which includes the poral vein, hepatic artery, and bile duct.
Once isolated, a suture is stitched around the left triad, and a hanging weight system is applied to induce liver ischemia At a certain time point after ischemia, the weights are lifted to begin reperfusion. Ultimately, the extent of liver injury following ischemia and reperfusion can be obtained by measuring a LT and a ST in the blood and performing liver histology. The main advantage of this technique over existing methods like utilizing clamps for liver ischemia is that the suture does not cause injury to the liver tissue and that the timing of ischemia can be more precise.
Visual demonstration of this method is critical as the exact placement of the suture is key to obtaining reproducible liver ischemia without harming the tissue. Begin by setting up the surgical area with sterilized instruments and all other materials required for surgery. To start place an anesthetized mouse in a supine position on a temperature controlled heated table.
Secure the upper and lower extremities to the table with removable tape to make Locating the triad and placing the suture easier. Position the mouse and heating table such that the tail is directed to the surgeon. Next, insert a rectal probe attached to a thermal feedback controller to maintain the body temperature.
Cover the incision area with mineral oil to prevent inhalation of mouse hair and reduce allergen exposure. Once the animal has been properly prepared, confirm the depth of anesthesia before performing a midline laparotomy. Continue cutting the linear alba until the liver can be easily exposed.
Next, use a wet cotton swab to displace the intestines and expose the portal triad. To gain a better view, shift the median and left lobe towards the diaphragm and the right lobe towards the intestine. Use bland forceps to hold down the right lobe and obtain a clear view of the left portal.
Triad and vena caver inferior. Carefully thread a suture around the left portal triad. This includes the hepatic artery, hepatic vein, and bile duct.
Use forceps to grab the tip of the needle from the right side and pull the suture gently through without damaging the liver. The stitch should be placed just under the triad any deeper, and it may injure the vena caver inferior. Once the suture is in place, attach a weighted eend orph tube to each end.
When ready, these weights will be placed over suture holders that are located distally of the stitch. As seen here to initiate ischemia, tra both weights over the suture holders. The triad will be occluded immediately causing an interruption of the blood supply to the left and median loaves of the liver.
Successful occlusion is confirmed by the pale blanching of the median and left liver lobes. This partial hepatic ischemia model avoids mesenteric congestion by preserving blood flow to the right liver lobes. When the predetermined ischemic period is over, lift the weights to relieve the tension on the suture.
A changing color should be apparent as the liver is reperfused. Place the intestine back into the abdominal cavity and keep the liver and intestine warm with a wet swab soaked with warm water. After the reperfusion period, blood and liver tissue can be collected to assess the extent of liver damage after hepatic ischemia.
The extent of liver injury can be determined by staining the tissue with hematin and eoin. The healthy tissue seen here contains less hepatocyte, ization and swelling as compared to the ischemic liver. The liver enzymes, alanine, and minor transferase a LT and to minor transferase A ST are common markers of liver damage here.
Levels of both a LT and A ST increased when the ischemic time period was increased. One master. This technique can be done within 10 minutes if it is performed properly.
Other methods like ischemic preconditioning can be performed in order to answer additional questions in regard to liver injury due to ischemia.
Overview
This study presents a novel murine model utilizing a hanging weight system for portal triad occlusion, aimed at investigating liver ischemia. The technique allows for precise control over ischemia timing without causing injury to liver tissue.
Key Study Components
Area of Science
- Neuroscience
- Hepatic Ischemia
- Reperfusion Injury
Background
- Ischemia and reperfusion injury are critical areas of study in liver research.
- Existing methods often cause additional tissue damage.
- A need for improved techniques that minimize harm while allowing for precise ischemia timing exists.
- This study introduces a method that addresses these challenges.
Purpose of Study
- To develop a murine model for studying liver ischemia.
- To evaluate the effects of ischemia and subsequent reperfusion on liver injury.
- To provide a visual demonstration of the technique for reproducibility.
Methods Used
- Isolation of the left liver triad (portal vein, hepatic artery, bile duct).
- Application of a hanging weight system to induce ischemia.
- Measurement of liver injury through blood enzyme levels and histological analysis.
- Visual confirmation of ischemia through liver color changes.
Main Results
- The hanging weight system effectively occluded blood flow to the liver lobes.
- Successful ischemia was confirmed by observable blanching of liver lobes.
- Reperfusion led to color changes in the liver, indicating restored blood flow.
- Increased liver enzyme levels correlated with longer ischemic periods.
Conclusions
- This novel technique offers a reliable method for inducing liver ischemia.
- It minimizes tissue damage compared to traditional methods.
- The model can facilitate further research into liver ischemia and reperfusion injury.
Frequently Asked Questions
Executive Industry Relevance
This hanging-weight system enables precise, reproducible induction of hepatic ischemia in mice without tissue damage from clamping, supporting mechanistic studies of ischemia-reperfusion injury. The model facilitates target validation and biomarker discovery in preclinical liver disease research by providing quantifiable injury readouts via ALT/AST serum levels. Its utility in preconditioning studies allows evaluation of cytoprotective interventions prior to lead compound screening.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses in ischemia-reperfusion pathways through controlled temporal occlusion of hepatic blood flow.
- Operational Value: Provides a standardized surgical approach that reduces variability in ischemia induction across experimental groups.
- Predictive Value: Correlates ischemia duration with serum ALT/AST elevation, offering a quantitative metric for pathway de-risking.
Screening & Assay Development
- Assay Readiness: Generates consistent liver injury phenotypes suitable for validating biomarker assays or pharmacological interventions.
- Reproducibility: The suture-based occlusion method ensures uniform ischemic insult, supporting high-throughput screening reproducibility.
- Scalability: Short procedure time (<10 minutes) and minimal equipment needs facilitate adaptation to multi-group study designs.
Translational & Preclinical Research
- Disease Relevance: Models clinical scenarios like hepatic resection or transplantation where ischemia-reperfusion injury contributes to graft failure.
- Translational Continuity: Serum ALT/AST measurements align with clinical liver injury biomarkers, enabling cross-species extrapolation.
- Mechanistic De-risking: Allows evaluation of cytoprotective agents or genetic modifiers before advancing to larger mammalian models.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target hypothesis testing to preclinical efficacy evaluation, particularly for liver-targeted therapeutics where ischemia-reperfusion is a liability concern.
- Discovery Biology: Supports functional validation of genes or proteins implicated in hypoxic stress responses via inducible, lobe-specific ischemia.
- Screening: Enables preparation of standardized ischemic liver samples for ex vivo drug sensitivity or metabolite profiling assays.
- Analytics: Provides quantitative serum enzyme (ALT/AST) and histological readouts to compare injury severity across conditions.
- Translational Research: Biomarker alignment with clinical liver injury markers supports go/no-go decisions in preclinical development.
- Enterprise Reuse: Establishes a reusable surgical platform for iterative testing of ischemia-modulating compounds or genetic interventions.
Operational & Enterprise Impact
- Scientific Value: Reduces confounding tissue damage from clamps, improving specificity of ischemia-reperfusion mechanistic studies.
- Operational Value: Eliminates need for specialized vascular clamps, lowering procedural complexity and equipment costs.
- Strategic Value: Enables precise ischemia timing for preconditioning studies, improving efficiency in cytoprotective compound evaluation.
- Portfolio Impact: Generates reliable injury data to inform risk-adjusted prioritization of liver-targeted candidates.
Implementation Considerations
- Requires microsurgical expertise in vessel isolation and suture placement without damaging adjacent structures.
- Necessitates sterile surgical setup, temperature regulation, and hemorrhage control materials.
- Demands standardized ischemia/reperfusion timing protocols across operators for data comparability.
- Limited to left lobe ischemia; right lobe perfusion must be confirmed to avoid confounding systemic effects.
- Relies on serum ALT/AST as primary injury endpoints; complementary histology recommended for mechanistic depth.
