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A model mimicking the clinical scenario of burn injury and infection is necessary for furthering burn research. The present protocol demonstrates a simple and reproducible rat burn infection model comparable to that in humans. This facilitates the study of burn and infections following burn for developing new topical antibiotic treatments.
Burn induction methodologies are inconsistently described in rat models. A uniform burn wound model, which represents the clinical scenario, is necessary to perform reproducible burn research. The present protocol describes a simple and reproducible method to create ~20% total body surface area (TBSA) full-thickness burns in rats. Here, a 22.89 cm2 (5.4 cm diameter) copper rod heated at 97 °C in a water bath was applied to the rat skin surface to induce the burn injury. A copper rod with a high thermal conductivity was able to dissipate the heat deeper in the skin tissue to create a full-thickness burn. Histology analysis shows attenuated epidermis with coagulative damage to the full-thickness extent of the dermis and the subcutaneous tissue. Additionally, this model is representative of the clinical situations observed in hospitalized burn patients following burn injury such as immune dysregulation and bacterial infections. The model can recapitulate the systemic bacterial infection by both Gram-positive and Gram-negative bacteria. In conclusion, this paper presents an easy-to-learn and robust rat burn model that mimics the clinical situations, including immune dysregulation and bacterial infections, which is of considerable utility for the development of new topical antibiotic drugs for burn wound and infections.
Burn injuries are among the most devastating forms of trauma, with mortality rates reaching 12% even in specialized burn centers1,2,3. According to recently published reports, ~486,000 burn patients require medical care annually in the United States, with nearly 3,500 deaths1,2,3,4,5,6. Burn injury imposes a major challenge for patients' immune system and creates a signif....
All procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of The University of North Carolina and were conducted in accordance with its established guidelines. Male and female Sprague Dawley rats (250-300 g) aged 7-9 weeks old were used for the experiments. All animals were housed in a 12 h:12 h light-dark cycle with free access to food and water ad libitum. Always work with your institutional veterinarian about an analgesic plan prior to study initiation.
The protocol presented here is highly reproducible and resulted in a third-degree, full-thickness burn injury in rats. The burn wound appears waxy white after burn induction (Figure 2B). The color of the burn injury changed from white to brown over the course of 72 h post burn (Figure 2B-E).
Histological analysis confirmed a full-thickness burn (depth >2.61 mm at 24 h post burn;
Several burn models have been presented to study the pathophysiology of burn injury8,12,16,17. In the present study, we employed a rat model to develop a simple and reproducible protocol to induce a full-thickness burn followed by bacterial infection to simulate an infected burn trauma in patients. The choice of the rat as the animal model to mimic human conditions is based on a balance of cost.......
The authors thank the Division of Comparative Medicine at the University of North Carolina for the provision and care of animals. We thank Lauren Ralph and Mia Evangelista in the Pathology Services Core for expert technical assistance with Histopathology/Digital Pathology, including tissue sectioning and imaging. This research was supported by a research grant from the Department of Defense (Award number W81XWH-20-1-0500, GR and TV).
....Name | Company | Catalog Number | Comments |
1 mL syringe | BD, USA | 309597 | Used to inject the analgesic |
1.7 mL Microtube | Olympus, USA | 24-282 | Used to carry morphine |
10% NBF | VWR, USA | 16004-115 | Used to fix the skin piece for staining |
30 mL syringe | BD, USA | 302832 | Used to inject the lactate ringer solution |
70% ethyl alcohol | Fischer Scientific, USA | BP28184 | |
Aperio AT2 Digital Pathology Slide Scanner with ImageScope software | Aperio, Technologies Inc., Vista, CA, USA | n/a | Scanning of H & E slides and analysis |
Cetrimide agar plates | BD, USA | 285420 | Selective media plates for Pseudomonas aeruginosa growth |
Copper rods | n/a | n/a | Used to induce the burn injury |
Cotton tipped applicators | OMEGA Surgical supply, USA | 4225-IMC | Used to apply eye ointment |
Electric shaver | Oster, USA | Golden A5 | Used to remove the dorsal side hairs |
Eye lube | Dechra, UK | n/a | The eye wetting agent to provide long lasting comfort and avoid eye dryness |
Fluff filled underpads | Medline, USA | MSC281225 | Used in the burn procedure |
Forcep | F.S.T. | 11027-12 | Used to hold the skin piece |
Gauze sponges | Oasis, USA | PK412 | Used to clean the applied nair cream from the dorsal side |
Heat-resistant gloves | n/a | n/a | Used to hold the heated copper rods |
Hematology Analyzer | IDEXX laboratories, USA | ProCyte Dx | |
Induction chamber | Kent Scientific, USA | vetFlo-0730 | Used to anesthesize the animals |
Insulin syringe | BD, USA | 329461 | |
Isoflurane | Pivetal, USA | NDC46066-755-04 | Used to anesthesized rats to induce a loss of consciousness |
Isoflurane vaporiser | n/a | n/a | |
Lactated ringer's solution | icumedical, USA | NDC0990-7953-09 | Used to resuscitate the rats |
L-shaped spreader | Fischer Scientific, USA | 14-665-230 | |
Mannitol Agar | BD, USA | 211407 | Selective media plates for Staphylococcus aureus growth |
Minicollect tubes (K2EDTA) | greiner bio-one, USA | 450480 | Used to collect the blood |
Morphine | Mallinckrodt, UK | NDC0406-8003-30 | This analgesia was used to induce the inability to feel burn injury pain |
Muller Hinton Broth | BD, USA | 275730 | |
Muller Hinton II Agar | BD, USA | 211438 | |
Nair hair removal lotion | Nair, USA | n/a | Used to remove the residual hairs on dorsal side |
Needle 23 G | BD, USA | 305193 | Used to inject the lactate ringer solution |
Normal saline | n/a | n/a | |
Spectrophotometer | ThermoScientific, USA | Genesys 30 | |
Sprague-Dawley rats, male and female | Charles River Labs | n/a | 7-9 weeks old for burn induction |
Surgical Scissor | F.S.T. | 14501-14 | Used to cut the desired skin piece |
Tissue collection tubes | Globe Scientific | 220101236 | |
Tissue Homogenizer | Kinematica, Inc, USA | POLYTRON PT2100 | Used to homogenize the tissue samples |
Water bath | Fischer Scientific, USA | n/a | Used to induce the burn injury |
Weighted heating pad | Comfytemp, USA | n/a | Used during the procedure to keep rat's body warm |
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