| BackgroundAs the largest organ of the human body,the skin is a natural protective barrier against damage from chemical,physical and biological hazards in the external environment,and is the body’s first line of defence.Skin photo-damage accelerates the ageing of the skin,and the physiological effects of ageing skin,such as barrier protection and immune regulation,are reduced to varying degrees,which has a serious negative effect on the maintenance of healthy skin.Long-wave UV and medium-wave UV are the main sources of skin photoaging,and epidemiological surveys show that skin photoaging accounts for80% of facial skin ageing.The condition of the skin is an important factor in measuring the health of the human body,and people have a higher demand for maintaining young and healthy skin.Skin photoaging leads to wrinkles,dryness,loss of elasticity and even stimulates the development of skin malignancies,which exacerbates the destruction of the normal physiological structure of the skin.Currently,UV protection includes physical shading,chemical sun protection,plant extracts and antioxidants.All these protective measures are effective against UVB,but none of them are fully satisfactory for a number of reasons,including poor patient compliance and lack of ease of use,which may compromise their effectiveness.Stem cells and their exosomes are currently a hot topic of research in the field of regenerative medicine and anti-ageing.As the main way for stem cells to function,stem cell exosomes are produced through paracrine action of stem cells and are delivered to cells to perform physiological functions,affecting the survival,proliferation,migration and gene expression of the recipient cells.Stem cell exosomes have played an important role in the prevention and treatment of diseases including cardiovascular,respiratory and hepatic diseases,but the use of stem cell exosomes for the prevention and treatment of UV damage in the skin is relatively unexplored in current research,and the mechanisms involved have not been explored.Whether stem cell exosomes can be used to prevent UV-induced skin photoaging is important to further enrich the prevention and treatment of skin photoaging and to improve the efficacy of skin photoaging in existing conditions.ObjectiveThis study was conducted to investigate the effect of huc MSC-exo on the cellular skin photoaging model based on the medium-wave UV-induced photoaging of human dermal fibroblasts and to preliminarily explore its possible mechanisms.MethodsHuc MSC cells were cultured in vitro using a serum-free exosome based culture.huc MSC-conditioned medium was collected and huc MSC-exo was extracted and characterized using ultra-high speed centrifugation;HDF cells were cultured in vitro and a UVB lamp was used for the construction of a skin photoaging cell model.huc MSC-exo was used to pre-treat HDF cells 24 h before illumination.HDF cells were pretreated with huc MSC-exo 24 h before illumination,and ROS levels were measured 0.5 h after illumination;cell proliferation activity was measured using an enzyme marker,cell cycle was measured using flow cytometry,and the cytoskeleton was labeled using a microfilament green fluorescent probe 48 h after illumination;senescent damage was detected using β-galactosidase 72 h after illumination,and the expression of MMP-1,COL-1 and IL-1 was measured using real-time fluorescent PCR and Western Blot,respectively.1 and IL-1 expression levels using real-time fluorescence PCR and Western Blot,respectively.ResultsIn this study,the ROS content in the model group was significantly higher than that in the control group,and the ROS production in the experimental group was significantly lower than that in the model group;the proliferation activity of cells in the model group was significantly lower,and that of cells in the experimental group increased;the S-phase cell content in the experimental group was lower than that in the model group,and the G0/G1-phase cell content was higher than that in the model group;the cytoskeleton aspect ratio in the experimental group tended to be normal,similar to that in the control group;The percentage of senescent cells in the model group was significantly higher than that in the experimental group;the expression of MMP-1 and COL-1 m RNA and protein were down-regulated and up-regulated respectively in the experimental group compared with that in the model group.In the above results,the differences between the model group and the control group and between the experimental group and the model group were all significant（P < 0.05）.ConclusionOur study was based on a photoaging model of HDF cells.The results showed that huc MSC-exo could regulate the growth of HDF cells,promote the post-photoaging repair of HDF cells,reduce DNA damage,delay the UVB-induced senescence of HDF cells and increase their proliferation activity.It also significantly reduces the expression of MMPs and decreases the degradation of extracellular matrix.We can clearly see that stem cell exosomes have great potential for development in the biomedical field,which will help the clinical application of stem cell exosomes. |
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