Model Introduction
The Full-Thickness Skin Defect Model is the gold standard for evaluating the efficacy of biomedical materials, regenerative medicine agents, and wound healing drugs. This model simulates clinical deep trauma, ulcers, or surgical incisions by establishing standardized circular full-thickness skin defects (extending to the fascial layer) on the backs of experimental rats.
By employing standardized surgical procedures, this model can be used to observe the promotional effects of regenerative silica, hydrogels, dressings, and various topical drugs on skin tissue regeneration, wound contraction, and re-epithelialization, providing high-quality experimental data support for the translation of scientific research.
Research Applications
This model is widely applied in the following research fields:
- Biomaterial Evaluation: Testing the biocompatibility and healing promotion effects of regenerative silica, artificial skin, biological scaffolds, and hydrogel dressings.
- Drug Screening: Evaluating the impact of topical growth factors, anti-inflammatory drugs, and antimicrobial agents on the wound repair cycle.
- Regenerative Medicine Research: Exploring the role of stem cell therapy and exosomes in the regeneration of skin appendages (hair follicles, sweat glands).
- Pathological Mechanism Exploration: Studying the molecular mechanisms of inflammatory response, granulation tissue formation, and collagen deposition during the wound healing process.
Experimental Design Key Points
To ensure the scientific validity and reproducibility of experimental results, MDL strictly controls the following key points in the design:
- Animal Selection: Adult SD rats (typically 8-12 weeks old) are selected to exclude the interference of age and hormone levels on regenerative capacity.
- Standardized Modeling:
- Precise Localization: Shave the dorsal fur and create symmetrical defects on both sides of the spine to eliminate individual differences.
- Uniform Specifications: Use a standardized punch or surgical instruments to create circular defects with a diameter of 1.6 cm (or customized as needed).
- Depth Control: The full thickness of the skin must be incised down to the fascial layer to ensure the model meets the definition of a “full-thickness defect.”
- Standardized Administration:
- Quantitative Application: Control the application thickness of experimental samples to 1-2 mm, ensuring even coverage that slightly exceeds the wound edges.
- Sterile Protection: Use sterile gauze dressings post-surgery to prevent animal scratching and environmental infection.
- Cycle Management: The observation period is typically 14 days (2 weeks). Debridement, photography, and re-administration are performed every 2 days to ensure continuous observation of efficacy.
Key Monitoring Indicators
1. Gross Observation and Image Analysis
- Wound Healing Rate: Periodically take high-resolution photographs and use image analysis software to calculate the percentage reduction in wound area and plot healing curves.
- Clinical Manifestations: Observe for signs of infection such as redness, exudation, or suppuration, as well as the timing of scab formation and detachment.
2. Histopathological Evaluation (Core Indicators)
- HE Staining and Panoramic Scanning: Collect full-thickness tissue from the healing site (down to the fascia) and observe the thickness of the neo-epidermis and the growth of granulation tissue through panoramic scanning.
- Degree of Re-epithelialization: Evaluate the migration distance of the epithelial tongue and the quality of wound closure.
- Appendage Regeneration: Observe the number of regenerated skin appendages such as hair follicles and sebaceous glands in the new tissue.
3. Collagen and Extracellular Matrix Analysis (Optional)
- Masson’s Trichrome Staining: Evaluate the arrangement density and maturity of collagen fibers.
- Immunohistochemistry (IHC): Detect the expression levels of CD31 (angiogenesis), Ki-67 (cell proliferation), and inflammatory cytokines (TNF-α, IL-6).
