A Study On The Correlation Between The Changes In The Expression Of Epidermal Stem Cell Markers And Time After Skin Wound In Mice

Objective:Wound age estimation is a key and difficult problem in forensic research.The current researches mainly focus on the correlation between the changes in the expression of protein and cytokines and time on the basis of skin injury and brain injury models.Skin injury is most common in cases,and the estimation of wound age becomes the key to the breakthrough of forensic work.Epidermis healing is the most important part of skin healing,and it is possible to use the changes of epidermal stem cells(ESC)in the process of skin healing to study the estimation of wound age.Integrin β 1,p63 and keratin 19(K19)are important surface markers of epidermal stem cells.Animal models of acid burn and alkaline burn in mice skin were established to study the expressions changes of integrin β1,p63 and keratin 19 at different times after injury,and to analyze the correlation between them and the wound age.Methods:Use Na OH and HCl respectively to establish the animal models of second-degree(superficial second degree to deep second degree)acid burn and alkaline burn in mice skin.Take skin samples from the injured area on the 1d,2d,3d,5d,7d,10 d,12d and 14 d after injury,carry out visual inspection,HE,immunohistochemical staining and other histopathological tests,compare the expression changes of epidermal stem cell markers including integrin β1,P63 and keratin K19 at different stages after injury,and perform statistical analysis to analyze the correlation between the expression changes of three markers and the time of skin injury.Results:Using 5mol/L sodium hydroxide(Na OH)on the skin of the mouse’s back can form the second-degree(superficial second degree to deep second degree)burn of mouse skin.During the process of skin healing,starting from group 1d,the thickness of the epidermis gradually increased at each time point,and reached the peak at d7,after which the thickness of the epidermis gradually decreased.There was a significant difference in the thickness of the epidermis(P<0.05)between the experimental group and the control group.In the control group,a little positive expression of epidermal stem cell marker p63 was found in the basal layer of epidermis,and the positive cells were arranged in a single layer,while the number of positively expressed cells of P63 in the experimental group increased,mainly distributed in the basal layer,stratum spinosum,and stratum granulosum of epidermis.The expression of P63 increased gradually,and reached the peak at 7d,and then decreased gradually.There was a significant difference in the count of p63 positive cells(P<0.05)between the experimental group and the control group;K19 and β1 had obvious positive expression in the epidermis,the average optical density of the two markers showed an early increase with time,then decreased gradually from3 d,and kept a low level from 5d.Using 6mol/L hydrochloric acid(HCL)on the skin of the mouse’s back can form the second-degree(superficial second degree to deep second degree)burn of mouse skin.During the process of skin healing,starting from group 1d,the thickness of the epidermis gradually increased at each time point,and reached the peak at 10 d,after which the thickness of the epidermis gradually decreased.There was a significant difference in the thickness of the epidermis(P<0.05)between the experimental group and the control group.In the control group,a little positive expression of epidermal stem cell marker p63 was found in the basal layer of epidermis,while the number of positively expressed cells of P63 in the experimental group increased,mainly distributed in the basal layer,stratum spinosum,and stratum granulosum of epidermis.The expression of P63 increased gradually,reached the peak at 10 d and then decreased gradually.There was a significant difference in the count of p63 positive cells(P<0.05)between the experimental group and the control group;K19 and β1 in the control group had obvious positive expression in the epidermis,the average optical density of the two markers showed an early increase with time,then decreased gradually from 3d,and kept a low level from 5d.Results:1.There was no significant difference in the process of skin healing after acid burn and alkaline burn.The epidermis significantly thickened and reached the peak at 7d or 10 d.The wound age can be estimated from the change of epidermal thickness;2.Epidermal stem cells play an important role in the process of epidermis healing after skin wound.Integrin β1,P63,and K19 were all positively expressed;3.Integrin β1 and K19 increased significantly in the early stage of epidermal healing,which can help us estimate the early time of injury.However,the correlation between the expression changes and the wound age in the middle and late stages of healing process was not obvious;4.Epidermal stem cell marker P63 increased first and then decreased in the process of epidermal healing,which was correlated with the wound age and could provide help for the estimation of wound age.