Background: Currently, there is a lack in therapy that promotes the reepithelialization of diabetic wounds as an alternative to skin grafting. Here, the authors hypothesized that extracellular vesicles from adipose-derived stem cells (ADSC-EVs) could accelerate wound closure through rescuing the function of keratinocytes in diabetic mice. Methods: The effect of ADSC-EVs on the biological function of human keratinocyte cells was assayed in vitro. In vivo, 81 male severe combined immune deficiency mice aged 8 weeks were divided randomly into the extracellular vesicle–treated diabetes group (n = 27), the phosphate-buffered saline–treated diabetes group (n = 27), and the phosphate-buffered saline–treated normal group (n = 27). A round, 8-mm-diameter, full-skin defect was performed on the back skin of each mouse. The wound closure kinetics, average healing time, reepithelialization rate, and neovascularization were evaluated by histological staining. Results: In vitro, ADSC-EVs improved proliferation, migration, and proangiogenic potential, and inhibited the apoptosis of human keratinocyte cells by suppressing Fasl expression with the optimal dose of 40 μg/mL. In vivo, postoperative dripping of ADSC-EVs at the dose of 40 μg/mL accelerated diabetic wound healing, with a 15.8% increase in closure rate and a 3.3-day decrease in average healing time. ADSC-EVs improved reepithelialization (18.2%) with enhanced epithelial proliferation and filaggrin expression, and suppressed epithelial apoptosis and Fasl expression. A 2.7-fold increase in the number of CD31-positive cells was also observed. Conclusion: ADSC-EVs improve diabetic wound closure and angiogenesis by enhancing keratinocyte-mediated reepithelialization and vascularization. Clinical Relevance Statement: ADSC-EVs could be developed as a regenerative medicine for diabetic wound care.

ecellularized adipose tissue represents a promising scaffold for adipose tissue engineering. Multiple decellular techniques have been demonstrated for decellularized adipose tissue preparation, for manufacture into scaffold materials with different properties, such as powder, sponge, or hydrogel. [1][2][3] Thermosensitive hydrogel liquefied at 4°C and solidified at 37°C was considered the most suitable material for softtissue filling because of its ability to be injected subcutaneously, its minimal invasiveness, and its plasticity for the irregular shape of soft-tissue defects. 4 However, inadequate angiogenesis and adipogenesis limits the recellularization and fat formation after decellularized adipose tissue grafting. 3,5,6 Adipose tissue regulates angiogenesis and adipogenesis through paracrine factors. 7,8 Previous studies have shown that adipose liquid extract, isolated by mechanical protocol from lipoaspirate,

Background: The healing of diabetic wounds is poor due to a collagen deposition disorder. Matrix metalloproteinase-9 (MMP-9) is closely related to collagen deposition in the process of tissue repair. Many studies have demonstrated that extracellular vesicles derived from adipose-derived stem cells (ADSC-EVs) promote diabetic wound healing by enhancing collagen deposition. Objective: In this study, we explored if ADSC-EVs could downregulate the expression of MMP-9 in diabetic wounds and promote wound healing by improving collagen deposition. The potential effects of ADSC-EVs on MMP-9 and diabetic wound healing were tested both in vitro and in vivo. Methods: We first evaluated the effect of ADSC-EVs on the proliferation and MMP-9 secretion of HaCaT cells treated with advanced glycation end product-bovine serum albumin (AGE-BSA), using CCK-8 western blot and MMP-9 enzyme-linked immunosorbent assay(ELISA). Next, the effect of ADSC-EVs on the healing, re-epithelialisation, collagen deposition, and MMP-9 concentration in diabetic wound fluids was evaluated in an immunodeficient mouse model via MMP-9 ELISA and haematoxylin and eosin, Masson’s trichrome, and immunofluorescence staining for MMP-9. Results: In vitro, ADSC-EVs promoted the proliferation and MMP-9 secretion of HaCaT cells.In vivo, ADSC-EVs accelerated diabetic wound healing by improving re-epithelialisation and collagen deposition and by inhibiting the expression of MMP-9. Conclusion: ADSC-EVs possessed the healing of diabetic wounds in a mouse model by inhibiting downregulating MMP-9 and improving collagen deposition.Thus ,ADSC-EVs are a promising candidate for the treatment of diabetic wounds .

Background: Random flaps are widely used for wound repair. However, flap necrosis is a serious complication leading to the failure of operation. Our previous study demonstrated a great proangiogenic potential of hypoxia-treated adipose-derived stem cells-extracellular vesicles (HT-ASC-EVs). Thus, we aim to evaluate the effect of HT-ASC-EVs in the survival and angiogenesis of random skin flap in rats. Methods: Adipose-derived stem cells-extracellular vesicles were respectively isolated from adipose-derived stem cell culture medium of 3 donors via ultracentrifugation. The expression of hypoxia-inducible factor 1α (HIF-1α) and proangiogenic potential of HT-ASC-EVs and ASC-EVs were compared by co-culturing with human umbilical vein endothelial cells. Forty male Sprague-Dawley rats were randomly divided into 3 group (n = 10/group). A 9 Â 3-cm random skin flap was separated from the underlying fascia with both sacral arteries sectioned on each rat. The survival and angiogenesis of flaps treated by ASC-EVs or HT-ASC-EVs were also compared. Laser Doppler flowmetry and immunohistochemistry were used to evaluate skin perfusion and angiogenesis of skin flaps on postoperative day 7. Results: Hypoxia-treated adipose-derived stem cells-extracellular vesicles further improve the proliferation, migration, tube formation with upregulated HIF-1α, and VEGF expression of human umbilical vein endothelial cells in vitro, compared with ASC-EVs. In vivo, postoperatively injecting HT-ASC-EVs suppressed necrosis rate (29.1 ± 2.8% vs 59.2 ± 2.1%) and promoted the angiogenesis of skin flap including improved skin perfusion (803.2 ± 24.3 vs 556.3 ± 26.7 perfusion unit), increased number of CD31-positive cells, and upregulated expression of HIF-1α in vascular endothelium on postoperative day 7, compared with ASC-EVs. Conclusions: Intradermal injecting HT-ASC-EVs improve the survival of random skin flap by promoting HIF-1α-mediated angiogenesis in rat model.