Exosomes Derived from E2F1^-/- Adipose-Derived Stem Cells Promote Skin Wound Healing via miR-130b-5p/TGFBR3 Axis

Background: Skin wound is a widespread health problem and brings extraordinary burdens to patients. Exosomes derived from adipose-derived stem cells (ADSC-Exos) are considered promising strategies for repairing skin wounds. E2F1 is a member of the E2F family of transcription factors involved in cell growth and apoptosis. E2F1 deficiency in mice enhances wound healing by improving collagen deposition and angiogenesis. Additionally, E2F1 can regulate the transcription and paracrine activity of multiple miRNAs, which will inevitably reshape the paracrine expression profile of ADSC-Exos. This study aimed to investigate the impact of transcription factor E2F1 deficiency on the functions of ADSC-Exos in promoting wound healing.

Methods: First, we obtained ADSCs from subcutaneous adipose tissues of WT and E2F1^-/- C57BL/6 mice and separated their exosomes, denoted as ADSC^WT-Exos and ADSC^E2F1-/--Exos. The wound healing effects of ADSC^WT-Exos and ADSC^E2F1-/--Exos in full-thickness skin wound models were investigated by wound images, H&E staining, and immunohistochemical staining. For the in vitro study, the abilities of ADSC^WT-Exos and ADSC^E2F1-/--Exos to promote cell activities, collagen formation, and angiogenesis were evaluated. The potential mechanism by which ADSC^E2F1-/--Exos promote wound healing was determined by miRNA sequencing, ChIP‒qPCR, and dual-luciferase assays.

Results: ADSC^E2F1-/--Exos accelerated wound healing by promoting collagen formation and angiogenesis. As a result, compared with the lower wound healing rate of 30.5% within 7 days in the control group and 42.3% in the ADSC^WT-Exo group, ADSC^E2F1-/--Exos significantly increased the wound healing rate to 72.5%. In vitro, ADSC^E2F1-/--Exos activated the function of fibroblasts and vascular endothelial cells. The loss of E2F1 promoted miR-130b-5p expression in ADSC^E2F1-/--Exos through transcriptional regulation. MiRNA high-throughput sequencing identified 12 differently expressed miRNAs between ADSC^E2F1-/- and ADSC^WT. ADSC^E2F1-/--Exos enhanced fibroblast activities via the miR-130b-5p/TGFBR3 axis and TGF-β activation.

Conclusion: Our results indicated that ADSC^E2F1-/--Exos effectively promoted wound healing by regulating the miR-130b-5p/TGFBR3 axis, thus providing a novel strategy of gene-engineered stem cell exosomes for accelerating wound healing.