Protective Effect Of Mouse Bone Marrow Mesenchymal Stem Cell-derived Exosomes On Photoaging Of UV-induced Mouse Dermal Fibroblast

Objective: The skin is an important protective barrier for the human There are two main reasons for its aging: one is the inevitable aging caused by the passage of time and hormonal changes,and is also called aging.The other is due to direct contact between the skin and the environment,causing skin damage and premature aging.Ultraviolet B radiation is the main environmental factor leading to skin aging,so this aging is also called photoaging.Long-term UVB radiation can cause serious adverse effects on the skin,which can lead to photoaging and even more skin cancer.Study data haves shown that UVB radiation-induced skin photoaging is associated with the increase of matrix metalloproteinase 1(MMP-1)and a decrease in collagen-I and elastin.Study data has shown that paracrine factors secreted by i PSCs,such as exosomes,are beneficial for photoaging dermal fibroblasts(DF).However,to date,few reports have demonstrated that murine mesenchymal stem cell-derived exosomes(BMSCs-exo)can alleviate UVA and UVB-induced skin photoaging.This study aimed to determine the protective effect of BMSCs-exo on UVA and UVB-induced photoaging MDF.Methods: First,mouse bone marrow mesenchymal stem cells(BMSCs)were cultured by adherent culture method.The morphology of BMSCs was observed under inverted microscope.BMSCs were identified by flow cytometry,and the exosomes derived from the supernatant were isolated.The morphology of exosomes was identified by transmission electron microscopy,and the surface markers of exosomes CD9,CD63 and CD81 were detected by Western Blot.Next,an MDF aging model was established,irradiated with quantitative UVB,unirradiated cells as the control group,and then treated with different concentrations of BMSCs-exo.The model was divided into the following four groups: BMSCs-exo zero-dose group,BMSCs-exo low-dose group and BMSCs-exo high-dose group,and the control group was established.Finally,the senescence of the treated MDF was detected by ?-galactosidase staining,and the MDF type I collagen(collagen-I),matrix metalloproteinase-1(MMP-1)and Protein expression of the protein(Elastin)elasticity were detected by Western Blot.Results: RESULTS: BMSCs were uniformly fusiform under light microscope.Flow cytometry showed that BMSCs surface markers CD34 and CD45 were negatively expressed,and CD73,CD90 and CD105 were positive.Ultra-high-speed centrifugation of BMSCs-exo was observed by transmission electron microscopy.It has a round cup-like structure with a diameter of 50-150 nm.The surface markers were positively expressed by Western Blot for CD9,CD63 and CD81.The rate of ?-galactosidase positive cells in the MDF control group was increased compared with the blank control group.Compared with the MDF control group,the proportion of ?-galactosidase positive cells in the BMSCs-exo low dose group was decreased.The proportion of?-galactosidase positive cells in the high dose group of BMSCs-exo decreased,but both were higher than the proportion of ?-galactosidase positive cells in the blank control group.(P<0.05),statistically significant.Compared with the blank control group,the expression levels of collagen-I and Elastin in the MDF control group were significantly decreased(P<0.05).Compared with the MDF control group,the expression of collagen-I and Elastin protein in the BMSCs-exo low-dose group and the BMSCs-exo high-dose group were significantly increased(P<0.05).However,its protein expression was still lower than that of the control group.Compared with the control group,the expression of MMP-1 protein in the MDF control group was significantly increased(P<0.05).Compared with the MDF control group,the expression of MMP-1 protein in the BMSCs-exo low-dose group and the BMSCs-exo high-dose group was significantly decreased(P<0.05),and the protein expression was still higher than that in the control group(P<0.05).P < 0.05,statistically significant.Conclusion: BMSCs-Exo treatment can improve the MDF aging process caused by UVA and UVB radiation,reduce the expression of MMP-1 protein in cells after UVB irradiation,and increase the expression of collagen-I and Elastin protein after irradiation.Thereby,UVB-induced MDF photoaging is inhibited to some extent.These results indicate that BMSCs-Exo has great potential for the treatment of skin aging.