| Objective: The role of mesenchymal stem cell-derived small extracellular vesicle(MSC-sEV)in tissue regeneration and repair is currently a research hotspot in life sciences.However,in the field of skin anti-aging,the role of MSC-sEV still remains to be explored.Skin photoaging is an exogenous skin aging induced by long-term solar exposure.This study aims at exploring the role and mechanism of human umbilical cord-derived MSCsEV(hucMSC-sEV)in skin photoaging models and providing theoretical basis to promote the transformation and application of MSC-sEV in the fields of skin disease prevention and medical aesthetics.Methods: A nude mice skin photoaging model was established by using UVA and UVB.A differential ultracentrifugation method established by the research group in the early stage was used to extract hucMSC-sEV.Before each round of UV irradiation,the back skin of nude mice was treated with hucMSC-sEV combined with microneedle roller,the PBS treatment group,0.05% retinoic acid treatment group,UV injury group,and untreated Ctrl group were used as controls.Macroscopic changes of the skin were respectively observed on the 35 th and 50 th days of modeling,and skin tissues were collected for Hematoxylin-eosin(HE)and Masson staining to observe the thickness of the dermis and epidermis as well as the structure of collagen fibers,to comprehensively evaluate the protective effect of hucMSC-sEV on skin photoaging.In vitro,low-dose and high-frequency UVA irradiation was used to construct a photoaging model of dermal fibroblast(DF)cells.Before UV irradiation,hucMSC-sEV was added to DF cells,and theβ-nicotinamide mononucleotide intervention group was used as a positive control group.Detection of senescent cells,oxidative stress levels,DNA damage,and the synthesis function of type 1 collagen were used to evaluate the intervention effect of hucMSC-sEV by SA β-gal staining,immunofluorescence,flow cytometry,and western blot.Transcriptome sequencing(RNA-seq)was performed on DF cells from Ctrl group,UV treatment group,and UV+sEV treatment group,then screen and verify the differentially expressed genes among three groups.After that,the functional mechanism of hucMSC-sEV was clarified by overexpressing the target gene in DF cells through transfection.Results: In the nude mice skin photoaging model,an increase in desquamation and wrinkles can be visible to eyes.HE and Masson staining results showed that the damaged skin stratum corneum thickens,while the thickness of epidermis and dermis decreases,collagen fibers break and extracellular matrix components are variably deposited.Compared to other intervention groups,hucMSC-sEV intervention can effectively improve skin aging phenotype,maintain skin thickness,and restore collagen fibers structure.In vitro cell model,UVA induced the increase of senescent DF cells,while hucMSC-sEV pretreatment could reduce the number of aging cells,inhibit UV-induced oxidative stress,DNA damage,matrix metalloproteinase-1 expression and the loss of collagen,which reveals that hucMSC-sEV can effectively prevent skin photoaging.Based on RNA-seq of the group Ctrl,UV and UV+sEV,pregnancy zone protein(PZP)was significantly upregulated after hucMSC-sEV treatment,which also be verified through in vitro and in vivo experiment.Further overexpression results showed that with the increasing of PZP,it could alleviate the oxidative stress damage caused by UVA and significantly inhibit the degradation of collagen and activation of DNA damage response in DF cells,indicating that PZP plays a key role in the protective effect of hucMSC-sEV on DF cells photoaging.Conclusion: HucMSC-sEV could effectively prevent skin photoaging,significantly inhibit cell senescence and DNA damage by upregulating the expression level of PZP,which is expected to provide new strategies for preventing skin aging. |
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