Refractory diabetic wounds can cause persistent inflammation and delayed healing due to hypoxia. Currently, no optimal solution is available. Exosomes of adipose stem cells (ADSCs-exo) may promote skin wound healing, however, molecular mechanisms remains mysterious. We found significantly enhanced survival and proliferation of adipose stem cells after hypoxia induction compared to normoxia. Here, we aimed to investigate if hypoxic adipose stem cells exosomes (HypADSCs-exo) participate in hypoxia adaptability and accelerate diabetic wound healing. Based on high-throughput sequencing, 215 microRNAs (miRNAs) were upregulated and 369 miRNAs downregulated in HypADSCs-exo compared to ADSCs-exo. Up-regulated miR-21-3p, miR-126-5p, miR-31-5p whereas down-regulated gene miR-99b and miR-146-a correlated with wound healing. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), miRNAs might regulate cell metabolism, differentiation and Transforming growth factor-β (TGF-β) function. Consistently, HpyADSCs-exo could promote diabetic wounds healing and inhibit inflammation through PI3K/AKT signaling pathway. Collectively, HpyADSCs-exo can promote diabetic wound healing as an alternative strategy to improve wound healing.

TGF-β1, upregulated in keloid tissue, promotes the proliferation, collagen formation and differentiation of dermal fibroblasts. miR-21 is one of microRNAs first found in human genome. The aim of our study is to explore the mechanisms of miR-21 in TGF-β1-induced scar fibroblasts proliferation and transdifferentiation. In the present study, first we found that TGF-β1 promoted scar fibroblasts proliferation and transdifferentiation via up-regulating miR-21 expression, which could be attenuated when miR-21 was inhibited. Overexpression of miR-21 had similar effect as TGF-β1 on proliferation and transdifferentiation. Additionally, TGF-β1 increased the expressions and activities of MMP2 and MMP9 in keloid fibroblasts, which was suppressed by miR-21 inhibition. Finally, the results demonstrated that PTEN/AKT signaling pathway played important role in TGF-β1-induced transdifferentiation. In conclusion, our study suggests that TGF-β1 promotes keloid fibroblasts proliferation and transdifferentiation via up-regulation of miR-21 and PTEN/AKT signalling pathway plays important role in this process, which provides a potential theoretical basis for clinical treatment of skin scars.

Background: MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate gene expression in the progress of proliferation, differentiation, and apoptosis. A keloid is considered to be a type of benign tumor. The exact contribution of miRNAs in keloid fibroblasts remains largely unknown. Methods: Loss and gain of function was used by transfecting the keloid fibroblast cells with chemically synthesized oligonucleotides complementary to microRNA-21 (miR-21). Expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in keloid tissues and adjacent normal skin tissues were investigated by quantitative real-time polymerase chain reaction and Western blot assay. Moreover, cell apoptosis and proliferation were checked in keloid cells, and related proteins were determined by Western blot assay. Results: MiR-21 inhibitor and mimic transfection changed the apoptosis and DNA synthesis. Of the 23 paired samples analyzed, expression of PTEN was low in keloid tissues relative to adjacent normal skin tissues. Cells showed an inverse correlation between miR-21 and PTEN protein after transfection. In addition, cell proliferation was increased when normal skin fibroblasts were transfected with miR-21 mimics. It is worth noting that the expression of phosphorylated AKT decreased to relatively low levels after miR-21 inhibitor treatment. Conclusions: This in vitro study demonstrates important interactions among miR-21 expression, keloid fibroblast apoptosis, cell proliferation, and some related proteins. These findings may provide some hints toward effective applications of miR-21 as a therapy target for keloids.

Fibrosis with unrelieved chronic inflammation is an important pathological change in keloids. Mitochondrial autophagy plays a crucial role in reducing inflammation and inhibiting fibrosis. Adipose stem cell-derived exosomes, a product of adipose stem cell paracrine secretion, have pharmacological effects, such as anti-inflammatory and antiapoptotic effects, and mediate autophagy. Therefore, this study aims to investigate the function and mechanism of adipose stem cell exosomes in the treatment of keloids. We isolated adipose stem cell exosomes under normoxic and hypoxic condition to detect their effects on keloid fibroblast proliferation, migration, and collagen synthesis. Meanwhile, 740YPDGFR (PI3K/AKT activator) was applied to detect the changes in autophagic flow levels and mitochondrial morphology and function in keloid fibroblasts. We constructed a human keloid mouse model by transplanting human keloid tissues into six-week-old (20–22 g; female) BALB/c nude mice, meanwhile, we applied adipose stem cell exosomes to treat the mouse model and observed the retention and effect of ADSC exosomes in vivo. ADSC exosomes can inhibit the PI3K/AKT/mTOR signaling pathway. The exosomes of ADSCs decreased the inflammatory level of KFs, enhanced the interaction between P62 and LC3, and restored the mitochondrial membrane potential. In the human keloid mouse model, ADSC exosomes can exist stably, promote mitochondrial autophagy in keloid tissue, improve mitochondrial morphology, reduce inflammatory reaction and fibrosis. Meanwhile, At the same time, the exosomes derived from hypoxic adipose stem cells have played a more effective role in both in vitro and in vivo experiments. Adipose stem cell exosomes inhibited the PI3K/AKT/mTOR pathway, activated mitochondrial autophagy, and alleviated keloid scars.

Purpose: Inhibition of cellular adaptation to hypoxia can cause persistent inflammation, thereby increasing tissue damage and complicating wound healing in diabetes patients. Regulating cellular adaptation to hypoxic environments can help in effective wound repair. Hypoxia-inducible factor (HIF)-1α is a key regulator of cell hypoxia. Extracellular vesicles (EVs) regulate wound repair. This study investigated the mechanism of HIF-1α overexpression in adipose-derived stem cell extracellular vesicles (ADSCs-hEVs) in the repair of diabetic wounds. Materials and Methods: HIF-1α expression in diabetes patients and healthy participants was studied. High-throughput sequencing, GO, and KEGG analysis revealed that ADSCs small extracellular vesicle hypoxia environments may increase HIF-1α expression by affecting cell metabolism, differentiation, and TGF-β secretion, or by altering the PI3K/AKT pathway. Effect of addition of ADSCs-hEVs on cell proliferation and migration was investigated using Western blotting, EdU assay, transwell assay, and migration. In vivo, after 7, 14, and 21 days, important factors for diabetic wound healing were evaluated by immunohistochemistry, qRT-PCR, Masson staining, and H&E staining. Results: HIF-1α expression decreased in the skin of diabetes patients; interleukin (IL)-6 expression increased, and growth factor-related indexes decreased. ADSCs-hEVs significantly increased the expression and secretion of growth factors, compared with ADSCs-EVs. In vivo, ADSC-hEV treatment accelerated the healing rate and improved the healing quality of diabetic wounds compared with ADSCs-EVs. Conclusion: Speed and quality of wound healing increased significantly in the ADSCs-hEVs group, which could inhibit early inflammation while promoting the secretion and expression of growth factors and extracellular matrix-related indexes.

MicroRNA-21 inhibits mitochondria-mediated apoptosis in keloid MicroRNA-21 inhibits mitochondria-mediated apoptosis in keloid