Experimental Study Of Fetal Dermal Mesenchymal Stem Cells In Alleviating The Development Of Early Burn Wounds

ObjectiveTo observe the effects of fetal dermal mesenchymal stem cells(FDMSCs)on the microenvironment of the stasis zone in the early burn wounds of rats,then to explore the feasibility for preventing and treating early burn wound progression through FDMSCs therapy.MethodsThe model of rat burn stasis zone was established through custom-made brass comb(with a transverse section of 20mm×10mm,the interspace section of 20mm×5mm,a total of 4 combs and 3 interspaces).The SD rats were randomly divided into three groups.First,the brass was boiled in 100℃ water for 5 min,and applied to the shaved skin surface of the rat dorsum for 20s.The control group was subcutaneously injected with PBS in the stasis area of the wound,the experimental group was subcutaneously injected with FDMSCs,and the blank group without burn.After 48 hours of burns,the interspace skin was harvested from each model,and the following indicators were detected:①Histology:The thickness of epidermis and dermis,skin appendages,collagen structure and tissue destruction in the stasis zone was observed by HE staining;②Inflammatory related factors:The expression of IL-1β and IL-6 was detected by RT-PCR and Western blot,and the protein expression levels of NF-κB p65 were evaluated by Western blot;③Oxidative stress:Relevant kits was performed to detect the content of malondialdehyde(MDA)and total superoxide dismutase(SOD);④Apoptosis:The expression of apoptosis-associated genes and proteins(Bax,Bcl-2)were evaluated by RT-PCR and Western blot.Results1)According to gross observation,hyperemia occurred in the stasis zone within 48 hours after burns in control group and experimental group,and the adjacent necrotic area had a tendency to fuse.2)HE staining demonstrated thinning of the epidermis layer,swelling of the dermis layer,alteration of collagen structure and infiltration of inflammatory cells in the stasis area of the control group.But FDMSCs can alleviate tissue destruction compared to the control group.3)FDMSCs lowered the expression of inflammatory related factors:RT-PCR and Western blot showed that the inflammatory factors IL-1β and IL-6 of the experimental group and the control group were higher than those of the sham group,but these indicators of the experimental group were significantly reduced compared with the control group.In addition,NF-κB p65 expression was down regulated by FDMSCs management.4)FDMSCs attenuate oxidative stress:According to the results of relevant kits,the burn-induced(experimental group and control group)increase in the end product of lipid peroxidation MDA was markedly reduced with FDMSCs.In addition,FDMSCs can reduce the consumption of endogenous antioxidant enzyme SOD,and its SOD expression is significantly higher than that of the control group.5)FDMSCs decrease cell apoptosis:The RT-PCR results showed that the Bax mRNA content decreased while the Bcl-2 mRNA content increased in the FDMSCs group;further Western blot results also showed that FDMSCs can promote the expression of the anti-apoptotic protein Bcl-2 and inhibit the expression of pro-apoptotic protein Bax,leads to the increase the ratio of Bcl-2/Bax and reduces cell apoptosis.ConclusionThe model of stasis zone in the early stage of burn can successfully constructed by brass-comb method.It can provide a reliable animal model for studying the early burn wounds progression.The experimental results show that FDMSCs may improve the microenvironment of the stasis area by attenuating local inflammation and oxidative stress,inhibiting cell apoptosis,and then alleviating the progression of stasis area.The effect of FDMSCs in inhibiting wound inflammation may be achieved by affecting the NF-κB signaling pathway.