Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2026 Apr 15;40(4):664-674. doi: 10.7507/1002-1892.202509067.
ABSTRACT
OBJECTIVE: To isolate extracellular vesicles (EVs) from the wound-edge skin tissue of type 2 diabetic foot ulcers and to investigate their effect on wound healing in mice.
METHODS: Twenty 8-week-old male db/db mice were used to establish a full-thickness skin defect wound with a diameter of 1.0 cm on the back, and divided into GW4869 (hydrochloride hydrate) group and DMSO group (control group), with 10 mice in each group. The wound healing rate was calculated on days 3, 6, 9, and 12 after injection. HE staining was used to observe epithelialization and inflammatory cell infiltration on days 7 and 12 after injection. Masson staining was used to observe collagen fiber formation. Immunofluorescence staining was used to detect CD206 and interleukin 1β (IL-1β) expressions in wound tissues. Skin tissues from the wound edge of 30 patients with type 2 diabetic foot ulcer were collected for tissue cutting, enzyme dissociation, gradient size exclusion, differential centrifugation combined with ultra-high speed centrifugation to extract tissue EVs (Dia-EVs), which were identified by transmission electron microscopy and particle size analysis. Twenty 8-week-old male C57BL/6 mice were used to establish a full-thickness skin defect wound with a diameter of 1.0 cm on the back, and divided into Dia-EVs group and PBS group, with 10 mice in each group. The wound healing rate was calculated on days 3, 5, 7, 9, and 12 after injection. HE staining was used to observe epithelialization and inflammatory cell infiltration on days 7 and 12 after injection. Masson staining was used to observe collagen fiber formation. Immunofluorescence staining was used to detect CD206 and IL-1β expressions in wound tissues. In vitro experiments were conducted using RAW264.7 cells, which were divided into three groups: the control group [cultured in PRMI 1640 medium containing 10% fetal bovine serum (FBS)], the M1 group [induced with PRMI 1640 medium containing 10%FBS, 200 ng/mL lipopolysaccharide, and 20 ng/mL interferon γ (IFN-γ) for 48 hours], and the Dia-EVs group (treated with PRMI 1640 medium containing 10%FBS and 40 μg/mL Dia-EVs for 48 hours). The expression levels of CD206 and IL-1β in each group of cells were observed.
RESULTS: In db/db mice experiment, on days 3, 6, 9, and 12 after injection, the wound healing rate of the GW4869 group was significantly faster than that of the DMSO group ( P<0.05). On day 7 after injection, inflammatory cell infiltration in the DMSO group was obvious, and the number of inflammatory cells was significantly higher than that in the GW4869 group ( P<0.05). Masson staining showed no obvious new collagen formation in either group. On day 12 after injection, HE staining showed that the GW4869 injection group had completed epithelialization without obvious inflammatory cell infiltration, while the DMSO injection group still had a large number of inflammatory cells infiltrating ( P<0.05). Moreover, a large amount of new collagen was formed in the GW4869 group, and the collagen volume ratio was significantly greater than that of the DMSO group ( P<0.05). On 7 days after injection, no significant CD206 positive expression was observed in either group, but a large amount of IL-1β positive expression was seen. Moreover, the IL-1β relative expression in the DMSO group was significantly more than that in the GW4869 group ( P<0.05). On 12 days after injection, CD206 positive expression was observed in the GW4869 group, while no significant expression was seen in the DMSO group ( P<0.05); no obvious IL-1β positive expression was found in the GW4869 group, while the DMSO group still had a large amount of IL-1β positive expression ( P<0.05). In C57BL/6 mice experiment, on days 3, 5, 7, 9, and 12 after injection, the wound healing rate of the Dia-EVs group was significantly slower than that of the PBS group ( P<0.05). On day 7 after injection, inflammatory cell infiltration in the Dia-EVs group was obvious, and the number of inflammatory cells was significantly higher than that in the PBS group ( P<0.05). Masson staining showed no obvious new collagen formation in either group. On day 12 after injection, wound defects still existed in both the Dia-EVs group and the PBS group, but the wound area in the PBS group was narrower. The number of inflammatory cells showed no significant difference ( P>0.05), while a large amount of new collagen formation was observed in the PBS group, significantly more than that in the Dia-EVs group ( P<0.05). Immunofluorescence results showed that on days 7 and 12 after injection, the number of IL-1β-positive cells in the Dia-EVs group was significantly higher than that in the PBS group ( P<0.05), while no significant CD206 positive expression was observed in either group ( P>0.05). In vitro experimental results showed that there was no significant difference in the relative expression of CD206 among the three groups ( P>0.05). The relative expressions of IL-1β in M1 group and Dia-EVs group were significantly higher than that in the control group ( P<0.05), but there was no significant difference between the two groups ( P>0.05).
CONCLUSION: Dia-EVs delay wound healing in mice by inducing M1 polarization of macrophages, inhibiting M2 transformation, and reducing collagen deposition.
PMID:41981442 | DOI:10.7507/1002-1892.202509067