[Animal modeling] - Comparative study on rat model of chronic skin ulcer

  Objective To establish a rat model of chronic skin ulcer by different methods, and evaluate the differences and characteristics of different models by comparing various indicators.

  Methods The rats were randomly divided into four groups. Different factors were applied on the basis of establishing the open wound of full thickness skin defect: skin defect group (skin defect group), skin defect+hormone interference group (skin defect+hormone group), skin defect+hormone interference+bacterial infection group (skin defect+actin+bacteria group), skin defect+foreign body group (skin defect+foreign body group); During the experiment, the body weight of rats was measured, their activity status and wound healing were observed. On the 14th day, materials were taken to observe the local pathomorphology of ulcer tissues, and the organ index of immune organs, the level of white blood cells, the content of hydroxyproline (Hyp), total protein and tumor necrosis factor-a (TNF-a) in granulation tissues were detected.

  Results During the experimental period, there was no significant difference in the weight of rats in each group. After modeling, the wound healing of rats in the skin lesion group was faster, and the "hard to heal" phenomenon in the skin lesion+hormone group was relatively short. The new granulation in the skin lesion+foreign body group was gray in the early stage, but the granulation grew faster in the late stage, while the wound in the skin lesion+hormone+bacteria group was characterized by yellow pus and slower granulation tissue growth; Pathological observation showed that the infiltration of inflammatory cells in the skin lesion+hormone+bacteria group and the skin lesion+foreign body group was significantly compared with the skin lesion group. The other three model groups showed an increase in spleen index, an increase in leukocyte level, a significant decrease in the content of hydroxyproline in the wound tissue (P<0.05 or P<0.01), and a significant decrease in the total protein content in the skin lesion+hormone+bacteria group (P<0.05), TNF- α The content was significantly increased (P<0.05).

  Conclusion The healing speed of skin ulcer in rats is slowed down in varying degrees after different intervention factors are superimposed on the basis of full thickness skin resection, and the pathological characteristics of the skin lesion+hormone+bacteria model are more stable and lasting for a long time, which can be used as the first choice model of chronic refractory skin ulcer. The skin lesion+hormone and skin lesion+foreign body models may be more suitable for the study of short-term refractory wounds, The latter can also be used to observe the growth of simple granulation at the early stage of the wound.