Isolation of Mouse Interstitial Valve Cells to Study the Calcification of the Aortic Valve In Vitro
May 10th, 2021
This article describes the isolation of mouse aortic valve cells by a two-step collagenase procedure. Isolated mouse valve cells are important for performing different assays, such as this in vitro calcification assay, and for investigating the molecular pathways leading to aortic valve mineralization.
The use of isolated mouse valve cells is essential to investigate the signaling pathway leading to valve calcification in the use of genetically modified cells from transgenic mice. The two-step digestion is a quick and efficient method. The most challenging part of this protocol is the isolation of the aortic valve from eight weeks mice.
It is better to practice on older mice to visualize the aortic valve better. Before starting the experiment, clean and sterilize all the surgical instruments and workspace with 70%ethanol and autoclave the surgical instruments for 30 minutes. When the initial setup is ready, start with cleaning the chest and the abdomen region of an eight week old euthanized mouse using ethanol.
Using scissors, open the abdomen and the chest of the mouse, then cut between the left atrium and the left ventricle with small surgical scissors. Remove blood from the heart by perfusing 10 milliliters of cold PBS and cut the heart, keeping three millimeters of the ascending aorta. Under a stereomicroscope, dissect the aortic valve by cutting the heart horizontally in the middle of the ventricles and cutting the left ventricle towards the aorta, then carefully dissect the aortic valve.
Pool the valves together in a small 35 millimeter tissue culture dish. Wash the isolated valves in a 75 milliliter cell culture dish with five milliliters of freshly prepared 10 millimolar cold HEPES supplemented with antibiotics and incubate in five milliliters of collagenase type one for 30 minutes at 37 degrees Celsius with continuous shaking. After incubation, centrifuge the tube for five minutes, at 150 times G and wash the pellet once with two milliliters of 10 millimolar HEPES with vortexing at high speed for 30 seconds.
Collect the resultant suspension from the tube into a 35 millimeter culture dish and use thin tweezers to carefully transfer the tissue fragments into a fresh tube. Then incubate the pellet in a 15 milliliter tube with five milliliters of collagenase type one at 37 degrees Celsius under continuous agitation for 35 minutes. Separate the cells by resuspending with a one milliliter pipette and centrifuge at 150 times G for five minutes at four degrees Celsius.
Clean the cells twice by resuspending the separated pellet in two milliliters of complete DMEM and centrifuging at 150 times G for five minutes at four degrees Celsius. For plating, resuspend the pellet in one milliliter of complete medium and add it to one well of a six well cell culture dish in a minimum amount of medium. Keep the plates undisturbed at 37 degrees Celsius with 5%carbon dioxide.
After three days of incubation, confirm growth close to the tissue debris by observing the cells under the microscope. Once 1, 000 cells are visible, carefully remove the tissue debris with autoclaved tweezers and change the medium. Trypsinize the cells after reaching 70%confluency and transfer them to a 75 milliliter tissue culture dish.
Before beginning the assay, clean the biosafety hood with 70%ethanol and warm the DMEM medium to 37 degrees Celsius. Next, seed 100, 000 cells per condition into six well plates in complete DMEM and culture at 37 degrees Celsius. After 24 hours, replace the supernatant medium with the calcifying medium and incubate the cells for seven days at 37 degrees Celsius, replacing the medium on the third day.
After seven days, measure the calcium concentration in a 96 well plate by using the Arsenazo III reagent and recording the absorbance at 650 nanometers. In the representative analysis, various valve cell phenotypes were identified with immunofluorescent staining after three to five days of culture. Mouse VIC's expressed vimentin and alpha SMA, the significant markers of valve cells.
Additionally, CD31 immunofluorescent staining verified no contamination from endothelial cells in VIC culture. Culturing VIC's with phosphate rich calcifying medium stimulate a calcification in cells, further confirmed with the red positive staining for calcium nodes. The protocol is based on a pool of three to five valve from different mice.
The use of litter mate and three different biological replicates is important to validate the findings. The use of mouse valve cells is vital to understand the molecular pathway leading to aortic stenosis by isolating cells from transgenic mice. This protocol has been used previously to investigate the implication of pathway to receptor in mineral regression of calcified aortic valve.
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Overview
This article details a two-step collagenase procedure for isolating mouse aortic valve cells, essential for studying molecular pathways involved in aortic valve calcification. The isolation method enables subsequent assays to evaluate valve mineralization.
Key Study Components
Research Area
- Cell biology
- Signaling pathways
- Aortic valve calcification
Background
- The significance of isolated valve cells in understanding calcification mechanisms.
- The challenges associated with isolating aortic valves from eight-week-old mice.
- The importance of transgenic mouse models in revealing molecular pathways.
Methods Used
- Two-step collagenase digestion for cell isolation.
- Mouse model, specifically aortic valves from transgenic mice.
- In vitro assays, including calcium concentration measurement with Arsenazo III reagent.
Main Results
- Successful isolation and culture of valve cells.
- Identification of valve cell phenotypes via immunofluorescent staining.
- Validation of findings through multiple biological replicates.
Conclusions
- This study presents an efficient method for isolating aortic valve cells, enhancing the understanding of molecular mechanisms in aortic stenosis.
- The findings contribute to broader biological research on heart valve calcification.
Frequently Asked Questions
Executive Industry Relevance
Reliable isolation and characterization of mouse valve interstitial cells (VICs) enables mechanistic interrogation of aortic valve calcification, a key driver of aortic stenosis. This workflow supports early discovery and target validation by providing a disease-relevant in vitro system for pathway analysis and pharmacological testing. The method enhances predictive confidence for translational research and portfolio triage in cardiovascular drug discovery.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables mechanistic de-risking by isolating VICs for pathway interrogation in calcification.
- Supports functional target validation using genetically modified mouse models.
- Facilitates hypothesis-driven testing of molecular drivers and inhibitors of mineralization.
- Provides a platform for evaluating new pharmacological targets in a controlled system.
Screening & Assay Development
- Delivers validated primary cell cultures for reproducible in vitro calcification assays.
- Standardizes cell phenotype confirmation via immunofluorescence for assay reliability.
- Enables quantitative measurement of calcification using calcium reagent and alizarin red staining.
- Prepares scalable systems for compound screening and comparative analysis.
Translational & Preclinical Research
- Aligns in vitro findings with disease-relevant mechanisms observed in aortic stenosis.
- Supports continuity from genetic models to preclinical validation of therapeutic hypotheses.
- Provides a platform for biomarker discovery and mechanistic studies in valve pathology.
- Reduces translational risk by modeling human disease processes in primary mouse cells.
Pipeline & Workflow Integration
This method integrates into the discovery continuum from early mechanistic studies to preclinical target validation in cardiovascular research.
- Discovery Biology: Enables hypothesis testing and pathway clarification in valve calcification.
- Screening: Provides reproducible, quantitative outputs for compound evaluation.
- Analytics: Supports statistical comparison of calcification across experimental conditions.
- Translational Research: Bridges in vitro mechanistic insights to in vivo disease models.
- Enterprise Reuse: Establishes a reusable workflow for diverse genetic backgrounds and pharmacological studies.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in target validation.
- Operational Value: Standardizes cell isolation and assay protocols for reproducibility and scalability.
- Strategic Value: Informs go/no-go decisions and optimizes resource allocation in early-stage cardiovascular programs.
- Portfolio Impact: Enables risk-adjusted prioritization of targets and compounds for advancement.
Implementation Considerations
- Requires expertise in mouse dissection and primary cell culture techniques.
- Needs access to sterile surgical instruments, biosafety hoods, and analytical reagents.
- Demands rigorous cross-team standardization for cell isolation and phenotype validation.
- Adaptable to various transgenic mouse models for pathway-specific studies.
- Dependent on careful dissection and pooling of valves to ensure sufficient cell yield and reproducibility.
