Human Umbilical Cord Blood NK Cell-derived Exosomes Promote Skin Wound HealingOA

To investigate the therapeutic efficacy and potential regulatory mechanisms of human umbilical cord blood natural killer(NK)cell-derived exosomes(NK-Exos)in a lipopolysaccharide(LPS)-induced inflammatory model,as well as their impacts on cutaneous wound healing in mice,exosomes were isolated from the culture supernatant of human umbilical cord blood-derived NK cells by ultracentrifugation and characterized by transmission electron microscopy(TEM),nanoparticle tracking analysis(NTA),dynamic light scattering(DLS),and Western-blot.Following co-culture of epidermal keratinocytes or LPS-stimulated macrophages with NK-Exo,the regulatory effects of NK-Exo on inflammatory cytokine expression were evaluated in vitro by Western-blot and real-time fluorescent quantitative PCR(RT-qPCR),and its impacts on the migration and proliferation of epidermal keratinocytes were assessed using the scratch wound healing assay and Transwell assay.Furthermore,a full-thickness skin defect model was established on the dorsum of mice.Following topical administration of NK-Exo,histological analysis was performed by hematoxylin and eosin(HE)and Masson staining to evaluate wound healing status and collagen deposition,and immunohistochemistry(IHC)was employed to detect the expression of F4/80 and Ki67 in wound tissue sections to assess inflammatory infiltration and cell proliferation.The results demonstrated that NK-Exo could be effectively internalized by recipient cells within 8 h,significantly downregulate the expression of pro-inflammatory cytokines(TNF-α,IL-6,iNOS,and IL-1β)in LPS-induced macrophages,and enhance the proliferation and migration of epidermal cells.In the mouse wound healing model,NK-Exo promoted cutaneous wound closure and collagen fiber deposition,while attenuating inflammatory cell infiltration and facilitating cell proliferation in the injured tissues.Collectively,these findings indicate that NK-Exo can alleviate inflammatory responses in injured skin tissues,promote cell proliferation and migration,and collagen formation.This study provides fundamental experimental data for the development of NK-Exo as a potential cell-free therapeutic strategy for skin wound repair and healing.