E2F1-deficiency Improves Adipose-derived Stem Cell-assisted Wound Healing By Up-regulating The Paracrine Expression Of VEGF And TGF-β1

Objective: Adipose-derived stem cells(ADSCs)possess significant potential for therapeutic benefits in the context of wound healing owing to their paracrine properties.The E2 F transcription factor 1(E2F1)participates in the regulation of the cell cycle and apoptosis,and can also act as a bidirectional regulator of various cytokines.However,it remains unclear as to whether E2F1 can regulate the paracrine signaling activity in ADSCs,or whether it is involved in the context of ADSC-assisted wound healing.Methods: ADSCs were separated from WT or E2F1-/-mice subcutaneous adipose tissues(denoted as WT ADSCs and E2F1-/-ADSCs).In vivo,the full-thickness wound healing mouse models were treated by injecting with PBS,WT ADSCs and E2F1-/-ADSCs separately.The wound closure area was monitored at day 0,3,7,10 and 14post-treatment.The histological pathology assays and western blotting(WB)were used to evaluate the therapeutic effects in each group.In vitro,WT ADSCs and E2F1-/-ADSCs were cultured under normoxic and hypoxic conditions,followed by the detection of the protein expression of VEGF and TGF-β1.The conditioned media(CM)of ADSCs was collected and co-cultured to analyse the abilities of proliferation,migration tube formation in fibroblasts or endothelial cells.Results: The E2F1-/-ADSCs group exhibited accelerated wound healing compared with control and WT groups.Furthermore,E2F1-/-ADSCs group exhibited a markedly higher microvascular density and endothelial cell proliferation,increased expression ofα-SMA and type I collagen in regeneration tissues.Moreover,E2F1-/-ADSCs enhanced VEGF and TGF-β1 protein expression in wound tissues.Accordingly,In vitro,VEGF and TGF-β1 protein levels were significantly higher in E2F1-/-ADSCs relative to in the WT ADSCs,both under normoxia and hypoxia.The CM from E2F1-/-ADSCs promoted the proliferation and migration of fibroblasts and tube formation of endothelial cells.Conclusion: Thus,the results demonstrated that E2F1 deficiency could increase the VEGF and TGF-β1 paracrine pruduction in ADSCs,by which the vascularization process and dermal regeneration were improved at wound sites,ultimately mediating the better therapeutic efficacy of ADSCs in the healing of cutaneous wounds.