Objective To explore the mechanism of adipose-derived mesenchymal stem cell-derived exosomes (hADSC-Exo) on wound healing of full-thickness skin defect in rats. Methods hADSC and hADSC-Exo were isolated and identified.
Human microvascular endothelial cells (hMECs) were divided into control group, positive control group (treated with 200 μg/L recombinant human epidermal growth factor) and hADSC-Exo group (treated with 100 μg/mL hADSC-Exo). The proliferation, migration and angiogenesis of hMECs were detected by CCK-8, scratch and angiogenesis experiments. A total of 60 rats were randomly divided into control group, positive control group, hADSC group and hADSC-Exo group, 15 rats in each group. Full-layer
skin defect wounds were prepared on the back of all rats. Each group was injected with 200 μL 1×PBS, 100 μg/kg recombinant
human epidermal growth factor, 200 μL 1×PBS containing 1×106 hADSC and 200 μL 1×PBS containing 200 μg hADSC-Exo, re
spectively. Three rats were randomly reserved in each group. The wound images were taken and the wound area was calculated
on the 0, 3, 7, 10 and 12 days respectively. The rest of the rats in each group were randomly divided into 4 groups, with 3 rats in
each group. The unhealed wound tissues were collected on the 3, 7, 10 and 12 days respectively, and tissue samples were prepared into paraffin sections. HE and Masson staining were used to observe the wound healing. The expression of proteins related
to inflammation and wound healing was detected by immunohistochemistry. Results The results of cell experiment showed
that compared with the control group, the cell proliferation activity, cell migration rate, lumen length and the number of branching points increased in the positive control group and hADSC-Exo group (P<0.05). Compared with the positive control group,
the cell proliferation activity, cell migration rate, lumen length and the number of branching points in hADSC-Exo group were
further increased (P<0.05). The results of animal test showed that compared with the control group, the wound healing rate and
the expression levels of CD206, Collagen Ⅰ , Collagen Ⅲ and Aquaporin 3 (AQP3) in the positive control group, hADSC group
and hADSC-Exo group increased (P<0.05), while the expression levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6,
CD68, keratin 1 (KRT1) and the ratio of Collagen Ⅰ /Collagen Ⅲ decreased (P<0.05), the new epidermis was more intact and
thicker, the proliferation of fibroblasts and the deposition of new collagen in the wound were significantly increased. Compared
with the positive control group, the expression levels of CD206, Collagen Ⅰ , Collagen Ⅲ and AQP3 in hADSC group and hADSC-Exo group were further increased (P<0.05), while the expression levels of TNF-α, IL-6, CD68, KRT1 were further decreased
(P<0.05). Conclusion hADSCs-Exos can enhance the proliferation, migration and angiogenesis of hMECs, reduce the level of
wound inflammation, promote the proliferation of wound cells, collagen remodeling, and accelerate wound healing, which has the
potential to be used as a treatment drug for skin wounds.
