A Mouse Model of Scald Wounds

Research Article

Austin J Emergency & Crit Care Med. 2016; 3(2): 1047.

A Mouse Model of Scald Wounds

Xiao Yongqiang, Zhang Fang and Xia Zhaofan*

Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China

*Corresponding author: Xia Zhaofan, Department of Burn Surgery, Changhai Hospital, Second Military Medical University, 168 Changhai Road, Shanghai, China Xiao Yongqiang and Zhang Fang Contributed equally to this work

Received: September 07, 2016; Accepted: November 01, 2016; Published: November 03, 2016

Abstract

Background: There were many mouse models of scald wounds have been created in the previous study. However, expensive materials, complicated and dangerous operation and poor repeatability were all disadvantages of most of these models. The purpose of this study was to establish a mouse model of scald wounds with controllable depth and area using some common consumables in the laboratory.

Materials and Methods: A homemade scald-producing device was produced in our laboratory by using some common consumables, including 50ml centrifuge tube, water bath kettle, thermometer etc. Twelve male C57BL/6 mice were randomly divided into two groups (n=6 in each group). Mice in control group were not burned. Mice in experiment group were scalded with hot water. More specifically, the mice in experiment group were fixed into the home-made fixture device, allowing the shaved dorsum expose to 90°C water for 9s. 24h later, skin samples of all mice in two groups were harvested for histopathological examination (H&E), masson staining and CD31 Immunohistochemistry assay. Terminal-Deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) assay was performed to detect the apoptosis of scald wound.

Results: This mouse model of full-thickness scald injury could be produced successfully by scalding with 90°C hot water for 9s. At 24h after scald, the skin tissues of mice in the experiment group exhibited the fractured and necrotic epidermal layer away from dermal layer, with almost unviable dermal hair follicles. Amounts of collagen degeneration, blood vessels necrosis and lots of increased apoptotic cells were demonstrated in scald skin. In addition, compared with the control group, coagulation necrosis and homogenization change of partial subcutaneous adipose tissue were observed in the scald skin. And even the superficial portion of some intradermal muscle layer was injured. The above experiments were repeated three times. The mouse model of scald wounds was successfully produced every time. The depth and area of burn were controllable. The model possessed a great repeatability.

Conclusions: These results indicated that the homemade scald-producing device could be successfully and conveniently used for producing the mouse model of scald wounds. Simple structures, low cost, transparent fixture device for easy observation and safe operation are all its advantages. Much more important, the depth and area are controllable through precise temperature control and standardized animal positioning.

Keywords: Mouse; Model; Scald wounds; CD31; Apoptosis

Introduction

Burns are one of the most general and fatal forms of trauma. Globally, the incidence of burn is still very high in modern life, especially in the developing countries. Immediate and specialized treatment was usually needed for patients with severe burn injury [1]. Over the past several decades, major advances have been made in the treatment of burns, and the survival rates for burn patients have improved dramatically. However, burn wounds still lead to serious mortality and morbidity, especially in children and adolescents [2]. Burn wounds often result in immune dysfunction, the delayed systemic inflammatory reaction, shock, sepsis, and some other severe complications [3-5]. Burns can also cause disability, disfigurement, lasting psychological and large economical burden to patients [6]. It is still necessary and urgent to keep going on studying on the treatment and pathogenesis of burn wounds.

Animal models of burn wound have been crucial to the advancement of the therapeutic methods of scald wound, which have made great contributions to the scientific research of cutaneous wound healing and the associated systemic effects. Because of the anatomical similarity to human’s skin, large animals were used firstly for burn models [7]. However, on account of ease of handling and using of a large number of animals for getting statistical significance, mouse models of thermal injury have been payed more and more attention.

Nowadays, the most frequently-used models are the contact burn and the scalding burn. The scalding model usually employs a template with an aperture, through which part of the body is immersed into a water bath with a controlled temperature for a specific period of time [8]. Most of these methods of making such a model are costly and complex. Expensive materials, dangerous operation and poor repeatability are all defects in the process of producing such burn models. So a feasible and convenient mouse model of scald burns is needed in the process of medical related animal experiments. Based on these requirements, we focused on creating a mouse model of scald injury with the following characteristics: (1) transparent fixture for easy observation, (2) low cost, (3) safe operation, (4) great repeatability, (5) simple structure, and (6) ease of handling.

Materials and Methods

Animals and materials

Twelve 20±3g male C57BL/6 mice, aged from 6 to 8 weeks, were provided by the Experimental Animal Center, Second Military Medical University, Shanghai. The mice were housed in cages under constant temperature (23-27°C), relative humidity (50%-70%) and 12h light/dark cycles. A certified diet and free access to water were provided to the mice. All animal experiment procedures were approved by the Ethics Committee of Animal Experiments of the Second Military Medical University (Shanghai, China), which was consistent with the Guide for Care and Use of Laboratory Animals published by the US NIH. Anti-CD31 was purchased from Abcam, Cambridge, Massachusetts. The TUNEL Apoptosis Detection Kit was purchased from Roche. And Masson’s Trichrome Stain Kit was provided by Sigma-Aldrich (St. Louis, MO, USA).

The structure of the scald apparatus

50ml centrifuge tube (Corning Incorporated, New York, USA), thermometer, water bath kettle, heat sources, and some other laboratory consumables were used for making scald apparatus. The apparatus mainly consisted of the fixture and heating device (Figure 2). Fixing device, made from 50ml centrifuge tube, included the handle (1), ventilation (2), skin contact window (3) and the cap (4). The ventilation could guarantee that the mouse in the tube could breathe smoothly, and through which the mouse tail was fixed out of the tube to avoid the scald of tail vein in the study. The handle was set in the upper of the tube, with which the operator could control the location and the time dipping in the hot water. The size of the skin contact window was designed according to the need of the scald area. The cap can prevent the hot water from entrying into the tube. The heating device mainly contains water bath kettle (5), thermometer (6), heat source (7) and some other common lab consumables.