Non-Invasive Visualization of Nailbed Microvascular Morphology in Mice Using Capillaroscopy
February 28th, 2025
Capillaroscopy is an accessible tool for direct, inexpensive, and non-invasive visualization of microvasculature. The goal of this protocol is to enable researchers to use capillaroscopy for the visualization of peripheral microvascular morphology in the nailbeds of mice.
One of our lab's interests is vascular dysfunction in neurodegenerative diseases. We aim to detect and monitor peripheral microvascular pathology via capillaroscopy to gain insight into its potential role in central nervous system diseases. Detecting microvascular dysfunction in animals is often invasive, carried out ex vivo, or expensive. With this protocol, researchers can easily and inexpensively assess the nailbed microvasculature and translate clinical nailfold capillaroscopy findings to animal models. We introduce a novel location for visualizing mirroring peripheral microvasculature, the nailbed. In comparison to nail fold capillaroscopy, nailbed capillaroscopy provides a larger area for better observation of microvascular morphology and structure.
[Instructor] To begin position the anesthetized mouse on the operating table for the procedure. Then apply lubricant eye gel or sterile non-medicated ophthalmic ointment to both eyes to prevent the cornea from drying. Then, maintaining the animal under anesthesia using a nose cone, apply a generous amount of hair-removal cream to the entire paw using an applicator. Ensure complete coverage of the paw and nailbed areas. After leaving the cream for two minutes, carefully clean away the hair-removal cream with a clean tissue, and wash the paw in lukewarm sterile water. 24 hours post fur removal, set up the capillaroscopy equipment in a temperature-controlled room maintained between 21.5 and 22.5 degrees Celsius. Connect the capillaroscope to a laptop computer via USB connection. Open the Debut video software application on the laptop. After the mouse is properly anesthetized, apply lubricant eye gel or sterile non-medicated ophthalmic ointment to both eyes. Place white laboratory tape or a similar background material under the paw to enhance contrast and improve vessel visualization. Now position the hind paw volar-side up on the lab tape platform, below the objective. Gently spread the toes to separate the nails under the microscope objective using an applicator. Ensure the nailbeds are clearly separated for optimal vessel imaging. Visualize what is being magnified by the capillaroscope and focus on the nailbed by adjusting the X-and Y-stage adjusters and the magnification wheel to obtain a clear image. To reduce glare and improve focus, generously Apply immersion oil to the paw, ensuring complete nail coverage. Focus on the nail of the second digit of the hind paw, as this is the largest nail, and easiest to image in mice. Adjust the X- and Y-stage adjusters and magnification wheel to bring the vessel network into focus. Adjust the objective to minimize glare and bring the nail vessel network into view. To record a video, hit the red Record button in Debut. Save each video to the appropriate project folder, and label each video accordingly. Next, open the ImageJ software, and drag the file into the software interface to load the image. To adjust the brightness and contrast, select image, followed by Adjust and Brightness/Contrast. This tool helps alter the contrast of the images to better visualize vessel morphology. Once the image has been adjusted, click Set in the Brightness/Contrast tool. Finally, go to File, Save As, and select Tiff to save the image. Nailbed vascular morphology was successfully imaged using the capillaroscopy method. Typical mouse nailbed vasculature consisted of an afferent vessel, an efferent vessel, and a network of capillaries connecting both. The nailbed capillary network was consistent across different mouse strains, as demonstrated in wild-type mice on an SV129/S6 background and a C57/B6J background.
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Overview
This study introduces a novel protocol for capillaroscopy, enabling researchers to visualize peripheral microvascular morphology in mouse nailbeds. This non-invasive method allows for the assessment of microvascular dysfunction, particularly in the context of neurodegenerative diseases.
Key Study Components
Research Area
- Microvascular pathology
- Neurodegenerative diseases
- Capillaroscopy techniques
Background
- Importance of studying vascular dysfunction in animal models
- Challenges of existing invasive or costly techniques
- Introduction of nailbed capillaroscopy as a better observation method
Methods Used
- Capillaroscopy procedure for imaging nailbed vessels
- Mouse models, specifically using wild-type strains
- Advanced imaging software for image capture and analysis
Main Results
- Effective imaging of nailbed vascularity
- Consistent nailbed capillary network across different mouse strains
- Successful application of the capabilities of capillaroscopy in assessing microvascular morphology
Conclusions
- Demonstrates a reliable and innovative approach to studying microvascular morphology
- Significant implications for research in vascular dysfunction related to neurological conditions
Frequently Asked Questions
Executive Industry Relevance
Non-invasive nailbed capillaroscopy in mice enables rapid, cost-effective visualization of peripheral microvascular morphology, addressing a critical translational gap between clinical and preclinical vascular research. This approach supports early detection and monitoring of microvascular dysfunction in disease models, enhancing predictive confidence for vascular-targeted drug discovery. Its scalability and reproducibility position it as a valuable asset for portfolio-wide mechanistic de-risking and target validation in systemic and neurovascular disorders.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct visualization of microvascular architecture for functional target validation in disease models.
- Supports mechanistic de-risking by providing morphological evidence of vascular involvement in systemic and neurodegenerative conditions.
- Facilitates hypothesis-driven interrogation of microcirculatory changes linked to therapeutic intervention.
Screening & Assay Development
- Provides a standardized, reproducible imaging platform for quantifying microvascular changes across mouse strains.
- Delivers high-contrast, quantitative outputs suitable for downstream image analysis and assay development.
- Enables scalable screening of compounds affecting peripheral microvasculature with minimal animal distress.
Translational & Preclinical Research
- Aligns preclinical microvascular readouts with clinical capillaroscopy endpoints, improving translational continuity.
- Supports risk-adjusted advancement decisions by enabling non-invasive, longitudinal monitoring of vascular pathology.
- Facilitates biomarker discovery for systemic and neurovascular disease models where microcirculation is implicated.
Pipeline & Workflow Integration
This capillaroscopy protocol integrates into the discovery-to-preclinical continuum, bridging early mechanistic studies and translational research in vascular biology.
- Discovery Biology: Provides direct, in vivo evidence for microvascular involvement in disease mechanisms.
- Screening: Offers reproducible, quantitative imaging outputs for compound evaluation and assay standardization.
- Analytics: Enables objective measurement of vessel morphology and network integrity using digital image analysis.
- Translational Research: Connects animal model findings to clinical microvascular endpoints, supporting biomarker alignment.
- Enterprise Reuse: Establishes a broadly applicable, non-invasive imaging capability for diverse disease models and therapeutic areas.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in vascular-targeted research.
- Operational Value: Delivers standardized, scalable, and cost-effective imaging workflows for cross-study comparability.
- Strategic Value: Improves go/no-go decision-making and capital efficiency by enabling early, non-invasive assessment of vascular endpoints.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of programs targeting microvascular dysfunction.
Implementation Considerations
- Requires expertise in small animal handling and digital image analysis.
- Needs standard capillaroscopy instrumentation and compatible imaging software (e.g., ImageJ).
- Demands cross-team alignment on imaging protocols and data interpretation standards.
- Adaptable to multiple mouse strains and disease models with peripheral vascular involvement.
- Limited to morphological assessment; functional or molecular endpoints require complementary assays.
