A Murine Tail Lymphedema Model
February 10th, 2021
Lymphedema is extremity swelling caused by lymphatic dysfunction. We describe a chronic murine tail model of lymphedema and the novel use of tissue nanotransfection technology (TNT) for genetic cargo delivery to the tail.
Lymphedema is a chronic condition with no cure. It affects one third of patients who have had an axillary lymph node surgery and radiation in the treatment of breast cancer. Having a valid animal model facilitates understanding the mechanism and development of novel treatment strategies.
The mouse tail model of lymphedema is reliable and reproducible with the rapid onset. It exhibits histological changes consistent with human lymphedema. Demonstrating the procedure will be Dr.Ganesh Mohan, a post-doctorate from my laboratory.
To begin, position the eight week old sedated mouse sternally and prep the tail with 70%isopropyl alcohol. Use a caliper to measure the tail diameter at five millimeter increments starting 20 millimeters from the base of the tail. Mark a three millimeter circumferential excision on the tail 20 millimeters from the base.
Under surgical microscopic magnification, perform a meticulous three millimeter full thickness skin excision leaving all the underlying vasculature intact. Incise the superior circumferential mark first through the dermis followed by a circumferential full thickness incision three millimeters distal to the first incision. Make a perpendicular full thickness vertical incision to connect the two incisions, then use a toothed fine pickup to grasp a leading edge and dissect deep within the avascular plane to the dermis and superficial to the vein adventitia with micro scissors.
Inject 0.1 milliliter of 1%isosulfan blue subcutaneously proximal to the tip of the tail. Identify the two lymphatic channels appearing blue due to the injection adjacent to the lateral tail veins. Transect the lymphatics carefully, dissecting a plane between the lateral vein and the lymphatic with straight microsurgical scissors.
Pass the tip of one scissor blade between the lymphatic vessel and the lateral vein and close the blades to transect the lymphatic vessel. When finished, dress the tail wound with a sterile adherent clear addressing. Administer indocyanine green 0.1 milliliter subcutaneously into the distal mouse tail near the tip.
Dim the room lights then place near infrared laser angiography in buffering setting and perform live imaging. After administration of isosulfan blue into the tail tip, the lymphatics exhibited blue color. The lymphatics were disrupted while adjacent lateral veins were preserved.
The progressive swelling and sustained persistent lymphedema in the mouse tail after lymphedema induction is shown here. The mouse tail volume as calculated by a truncated cone equation, peaked at week four and plateaued to week six followed by gradual improvement that was sustained until week 15. High-resolution laser speckle contrast imaging was done to confirm mouse tail perfusion in the lymphedema tail model showing injured lateral veins and intact lateral veins for assessment of tail vasculature patency.
Near infrared laser lymphangiography demonstrated preoperative intact lymphatics and no ICG transit beyond surgical site post-operatively, thereby confirming that swelling was caused by lymphatic disfunction. The efficiency of genetic cargo delivery using tissue nanotransfection technology was demonstrated by delivering fluorescein amidite labeled DNA to the murine tail. Using adaptations for the mouse tail lymphedema model and ICG near infrared laser angiography is a clinically translatable and exciting animal model with treatment implications.
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Overview
This study presents a chronic murine tail model of lymphedema, a condition characterized by extremity swelling due to lymphatic dysfunction. The research highlights the innovative use of tissue nanotransfection technology (TNT) for delivering genetic material to the affected tail.
Key Study Components
Area of Science
- Neuroscience
- Biology
- Regenerative Medicine
Background
- Lymphedema is a chronic condition with no cure, affecting many patients post-surgery for breast cancer.
- A reliable animal model is essential for understanding the mechanisms and developing treatment strategies.
- The mouse tail model shows histological changes similar to human lymphedema.
- This study aims to demonstrate the procedure and its implications for treatment.
Purpose of Study
- To establish a reproducible murine model of lymphedema.
- To utilize TNT for effective genetic cargo delivery.
- To assess the model's potential for future therapeutic applications.
Methods Used
- Preparation of the mouse tail and surgical excision techniques.
- Injection of isosulfan blue to visualize lymphatic channels.
- Use of near-infrared laser angiography for live imaging of lymphatics.
- Assessment of tail volume changes and vascular patency over time.
Main Results
- The model exhibited progressive swelling and sustained lymphedema.
- High-resolution imaging confirmed the integrity of adjacent veins.
- TNT successfully delivered genetic material to the tail.
- The model shows potential for clinical translation in lymphedema treatment.
Conclusions
- The murine tail model is a valid tool for studying lymphedema.
- TNT offers a novel approach for genetic interventions.
- This research paves the way for future therapeutic strategies in lymphedema management.
Frequently Asked Questions
Executive Industry Relevance
Establishing reliable preclinical models of lymphatic dysfunction is critical for de-risking therapeutic target validation in lymphedema, a condition with significant unmet medical need. This chronic murine tail lymphedema model supports sustained phenotype assessment over 15 weeks, enabling longitudinal evaluation of intervention efficacy. The integration of functional imaging and tissue nanotransfection technology enhances translational relevance by facilitating mechanistic studies and targeted genetic payload delivery in a vascularly intact system.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of lymphatic-specific therapeutic hypotheses through sustained induction of lymphedema without vascular compromise.
- Operational Value: Provides a reproducible platform for validating targets involved in lymphangiogenesis, fluid homeostasis, and fibrosis pathways.
- Predictive Value: Supports mechanistic de-risking by modeling human-like histological progression including adipose accumulation and fibrosis.
Screening & Assay Development
- Scientific Value: Facilitates development of quantitative lymphatic function assays using indocyanine green near-infrared lymphangiography for real-time readouts.
- Operational Value: Enables standardization of perfusion assessment via high-resolution laser speckle contrast imaging to confirm arterial and venous integrity.
- Scalability Value: Supports adaptation for high-content screening of compounds or genetic modifiers affecting lymphatic repair.
Translational & Preclinical Research
- Translational Value: Maintains tail perfusion and sustained swelling over 15 weeks, improving clinical translatability over acute models.
- Biomarker Alignment: Allows correlation of imaging-based lymphatic dysfunction with volumetric and histological endpoints relevant to human disease.
- Therapeutic Continuity: Supports evaluation of tissue nanotransfection-mediated delivery as a strategy for localized genetic intervention in vascularized tissue.
Pipeline & Workflow Integration
The model fits within the discovery-to-preclinical continuum by providing a validated system for target engagement studies prior to lead optimization and efficacy testing in disease-relevant contexts.
- Discovery Biology: Supports hypothesis-driven validation of lymphatic-specific targets through functional disruption and phenotypic readouts.
- Assay Readiness: Generates quantifiable outputs including tail volume measurements, lymphatic flux imaging, and vascular patency confirmation.
- Analytics Enablement: Provides longitudinal datasets for statistical comparison of intervention effects across timepoints up to week 15.
- Translational Bridge: Connects mechanistic findings to preclinical validation via clinically relevant imaging modalities and sustained phenotype.
- Platform Reuse: Establishes a standardized surgical and imaging workflow adaptable across laboratories for consistent model generation.
Operational & Enterprise Impact
- Scientific Value: Reduces biological ambiguity in lymphatic target validation through a clinically relevant, surgically precise model.
- Operational Value: Enhances reproducibility via standardized excision, lymphatic clipping, and perfusion confirmation protocols.
- Strategic Value: Improves go/no-go decision confidence by enabling sustained phenotype assessment beyond transient swelling models.
- Portfolio Impact: Supports risk-adjusted prioritization of lymphatic-targeted candidates using a model with demonstrated 15-week stability.
Implementation Considerations
- Requires microsurgical expertise and access to surgical microscopy for precise tissue excision and lymphatic identification.
- Dependent on imaging infrastructure including laser speckle contrast and near-infrared angiography systems for functional validation.
- Necessitates standardization of postoperative care and monitoring protocols to ensure tail viability and model consistency.
- Involves adaptation considerations when translating the model to different genetic backgrounds or comorbidity models.
- Limited by the need for specialized training in tissue nanotransfection delivery techniques for genetic cargo applications.
Biopharma FAQs
Chapters in this video
0:04
Introduction
0:53
Surgical Disruption of Mouse Tail Lymphatics
2:33
Functional Lymphatic Evaluation with Near Infrared Laser Angiography
2:54
Result: Assessment of Progressive Swelling, Lymphatic Function, and Focal Delivery of Genetic Cargo in the Mouse Tail Lymphedema Model
4:09
Conclusion
