Exosome Derived from Mesenchymal Stem Cells Alleviates Hypertrophic Scar by Inhibiting the Fibroblasts via TNFSF-13/HSPG2 Signaling Pathway.

Background: Mesenchymal stem cell-derived exosomes (MSC-exo) have been shown to have significant potential in wound healing and scar relief processes. According to reports, TNFSF13 and HSPG2 are associated with various fibrotic diseases. The aim of this study is to investigate how TNFSF13 and HSPG2 affect the formation of hypertrophic scar (HS) and the mechanism by which exosomes regulate HS. Methods: Immunohistochemistry, qRT-PCR, Western blot, and immunofluorescence were performed to measure TNFSF13 expression in HS skin tissues and hypertrophic scar fibroblast (HSF). HSF were treated with recombinant TNFSF13 protein and TNFSF13 siRNAs to probe the effect of TNFSF13 on the activity of HSF. The CCK-8, EdU, Transwell, and Western blot were used to investigate the role of TNFSF13 in viability, proliferation and inflammation. The influence of MSC-exo on the proliferation and function of HSF was determined by scratch and Western blot. Results: TNFSF13 was dramatically up-regulated in HS skin tissues and HSF. Recombinant TNFSF13 protein increased cell viability, proliferation, migration, fibrosis, inflammation, and the binding between TNFSF13 and HSPG2 of HSF. The opposite results were obtained in TNFSF13 siRNAs transferred HSF. Furthermore, TNFSF13 activated the nuclear factor-κB (NF-κB) signaling pathway. Silencing of HSPG2 and inhibition of NF-κB remarkably eliminated the promoting effects of TNFSF13 on cell viability, proliferation, migration, fibrosis and inflammation of HSF. MSC-exo reduced α-SMA and COL1A1 inhibited the proliferation and migration of HSF by inhibiting TNFSF13 and HSPG2. Conclusion: TNFSF13 activates NF-κB signaling pathway by interacting with HSPG2, which regulates the proliferation, migration, fibrosis and inflammatory response of HSF. Through the above mechanisms, knocking out TNFSF13 can inhibit the proliferation, migration, fibrosis and inflammatory response of HSF, whereas MSC-exo could reverse this process. These results suggest that MSC-exo alleviates HS by inhibiting the fibroblasts via TNFSF-13/HSPG2 signaling pathway.

The Sphingolipids Metabolism Mechanism and Associated Molecular Biomarker Investigation in Keloid.

BACKGROUND: Sphingolipid metabolism plays important roles in maintaining cell growth and signal transduction. However, this pathway has not been investigated in keloid, a disease characterized by the excessive proliferation of fibroblasts. METHODS: Based on the expression profiles of three datasets, the differentially expressed genes (DEGs) were explored between keloid fibroblasts and normal fibroblasts. Metabolism-related genes were obtained from a previous study. Then, enrichment analysis and protein-protein interaction (PPI) network analysis were performed for genes. Differences in metabolism-related pathways between keloid fibroblasts and normal fibroblasts were analyzed by the gene set variation analysis (GSVA). Quantitative PCR was used to confirm the expression of key genes in keloid fibroblast. RESULTS: A total of 42 up-regulated co-DEGs and 77 down-regulated co-DEGs were revealed based on three datasets, and were involved in extracellular matrix structural constituent, collagencontaining extracellular matrix and sphingolipid metabolism pathway. A total of 15 metabolism- DEGs were screened, including serine palmitoyltransferase long chain base subunit (SPTLC) 3, UDP-glucose ceramide glucosyltransferase (UGCG) and sphingomyelin synthase 2 (SGMS2). All these three genes were enriched in the sphingolipid pathway. GSVA showed that the biosynthesis of glycosphingolipids (GSLs) in keloid fibroblasts was lower than that in normal fibroblasts. Quantitative PCR suggested SPTLC3, UGCG and SGMS2 were regulated in keloid fibroblasts. CONCLUSION: Sphingolipids metabolism pathway might take part in the disease progression of keloid by regulating keloid fibroblasts. SPTLC3, UGCG and SGMS2 might be key targets to investigate the underlying mechanism.

Exosome Derived from Mesenchymal Stem Cells Alleviates Pathological Scars by Inhibiting the Proliferation, Migration and Protein Expression of Fibroblasts via Delivering miR-138-5p to Target SIRT1.

Introduction: The therapies of using exosomes derived from mesenchymal stem cells (MSC-Exo) for wound healing and scar attenuation and micro RNAs (miRNAs) for regulation of genes by translational inhibition and mRNA destabilization obtained great achievements. Silent information regulator 1 (SIRT1) is the silent information, which has an intricate role in many biological processes. However, the effects of SIRT1 and miR-138-5p loaded in MSC-Exo on pathological scars remain unclear. Methods: MSC-Exo was isolated and identified by ultracentrifugation, transmission electron microscopy, nanoparticle size measuring instrument and Western blot assays. The relationship between SIRT1 and miR-138-5p was verified by a double-luciferase reporter assay. Cell Counting Kit-8, Τranswell, scratch, and Western blot assays were used to evaluate the proliferation and migration of human skin fibroblasts (HSFs), and the protein expression of SIRT1, NF-κB, α-SMA and TGF-ß1 in HSFs, respectively. Flow cytometry was used to assess the apoptosis and cell cycle of HSFs affected by SIRT1. Results: Our study demonstrated that miR-138-5p loaded in MSC-Exo could attenuate proliferation, migration and protein expression of HSFs-derived NF-κB, α-SMA, and TGF-ß1 by targeting to SIRT1 gene, which confirmed the potential effects of MSC-Exo in alleviating pathological scars by performing as a miRNA's delivery vehicle. Conclusion: Exosomes derived from MSCs acting as a delivery vehicle to deliver miR-138-5p can downregulate SIRT1 to inhibit the growth and protein expression of HSFs and attenuate pathological scars.

STING activation promotes inflammatory response and delays skin wound healing in diabetic mice.

Sustained inflammatory responses delay wound repair in diabetic skin. The stimulator of interferon genes (STING) plays a vital role in the innate immune responses. However, its function in diabetic skin wound repair, and the underlying mechanism remains unclear. Here, we reported that STING activation is a pathogenic marker that correlates with delayed wound repair in diabetic skin. Firstly, we found that STING expression is enhanced in the epidermis of STZ induced diabetes mouse model and db/db mouse model. Consistently, we also found that STING expression was upregulated in keratinocytes with the high-glucose (HG) treatment. Moreover, silencing of STING accelerated wound healing in vitro. In vivo, inhibition of STING by c176 inhibited inflammatory response in the epidermis and accelerated wound healing in diabetic skin. In addition, we found that autophagy dysfunction is correlated with the expression of STING in epidermis of diabetic mice. Induction of autophagy by rapamycin significantly reduced STING expression in keratinocytes. Collectively, these results indicated that defects of autophagy might lead to the activation of STING and finally delay the diabetic wound healing.

Ultrasonography Superior Over Visual Assessment in Evaluation of Wound Healing After Dermabrasion.

BACKGROUND: Dermabrasion as one kind of treatment for partial thickness wounds is controversial. Visual assessment as the main way to evaluate the healing process of burn wounds is also inaccurate. In this study we try to explore whether dermabrasion accelerates healing in wounds of partial thickness and determine a reliable way to evaluate epithelialization. MATERIALS AND METHODS: Eight female Bama minipigs were anesthetized, and eighteen partial thickness wounds (circle, 4.0 cm2, symmetrically located at both sides of the spine) were produced on each. Wounds on the left side underwent dermabrasion (group D), and wounds on the right side did not (group N). All wounds were covered with allogenic skin (premade). The healing processes of the wounds were observed through three different ways, which included visual assessment, ultrasonography, and histological observation. The epithelialization rate (ER) for each day was plotted together to form a healing curve, by which theoretical mean healing times could be determined ("healed" was classified as ER = 95%). RESULTS: Through visual assessment, the healing times of group D and group N were 13.6 and 18.0 d, respectively. Using ultrasonography, wounds of group D and group N healed at 5.0 and 10.4 d, respectively. Through histological observation, full epithelialization was seen at 5.0 d in group D and at 10.2 d in group N. The healing curves based on visual assessment deviated far from those based on ultrasonography and histological observations, the two of which were almost duplicated. CONCLUSIONS: Earlier epithelialization could be seen in wounds of partial thickness burns after dermabrasion. It would be more accurate and reliable to monitor the epithelialization process through ultrasonography than visual assessment.

The role of TrkA in the promoting wounding-healing effect of CD271 on epidermal stem cells.

CD271, a receptor of nerve growth factor (NGF), affects the biological properties of epidermal stem cells (eSCs) which are essential for skin wound closure. Tropomyosin-receptor kinase A (TrkA), another receptor of NGF, combined with CD271 has been involved with nervous system and skin keratinocytes. However, the exact role of TrkA combined with CD271 in eSCs during skin wound closure is still unclear. This study aimed to reveal the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs. We obtained CD271-vo (over-expression of CD271) eSCs by lentiviral infection. K252a was used to inhibit TrkA expression. Full-thickness skin mouse wound closure model (5 mm in diameter) was used to detect the ability of CD271 over-expressed/TrkA-deficient during wound healing. The biological characteristics of eSCs and their proliferation and apoptosis were detected using immunohistochemistry and western blot. The expressions of protein kinase B (pAkt)/Akt, phosphorylated extracellular-signal-related kinase (pERK)/ERK1/2, and c-Jun N-terminal kinase (pJNK)/JNK were also detected by western blot. We found that over-expression of CD271 promoted the biological functions of eSCs. Interestingly, over-expression of CD271 in the absence of TrkA neither promoted eSCs' migration and proliferation nor promoted wound healing in a mouse model. In addition, we observed the reduced expression of pAkt/Akt and pERK/ERK1/2 following TrkA inhibition in vitro. Our studies demonstrated that the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs.

Nationwide web survey of pediatric scalds: Prevalence and the relationship with household vacuum flasks.

OBJECTIVE: To explore the prevalence of pediatric (0-72 months old) scalds, and to clarify its relationship with household vacuum flasks. METHODS: A cross sectional online survey based on the largest social media in China. Online questionnaire was pushed twice a day to our target respondents for successive seven days. We were authorized to gain, analyze and publish the information related to this research by the Sina & Weibo data center. RESULTS: Prevalence of pediatric scalds was 5.5%. Gender ratio (boy to girl) was 1.96:1. Toddlers (12-36 months old) were the most susceptible age group (54.5%). Non-intentional water spill was the main causation (77.3%). An extremely low percent (7.1%) of the parents performed first-aid as described by the "RRICH" rule: water rinse - clothes remove - water immersion - clean cover - hospital. Scars developed in 52.7% patients and 14.7% of them underwent reconstructive surgery. There were 75.5% Chinese families using vacuum flasks in daily life, but only 6.1% families used the fastening device to avoid burns. CONCLUSION: Prevalence of pediatric scalds (0-72 months old) was rather high, which might be related to the extensive insecure usage of household vacuum flasks.