Genome-Wide Search Links Senescence-Associated Secretory Proteins With Susceptibility for Coronary Artery Disease in Mouse and Human.

Advanced age is an independent risk factor for coronary artery disease (CAD), the leading global cause of mortality. Senescent vascular cells in the atherosclerotic plaques exhibit senescence-associated secretory phenotype (SASP). How SASP contributes to atherosclerosis and CAD, however, remains unclear. Here, we integrated RNA-array datasets of senescent human coronary arterial endothelial cells (HCAECs) and aortic smooth muscle cells (HASMCs) as well as genome-wide association data for CAD. We identified 26 genes from HCAECs and 6 genes from HASMCs related to SASP and CAD in both in-house and published datasets. Of which, Cystatin C (CST3), a CAD susceptibility gene, was found to be expressed in both HCAECs and HASMCs, thus, it was prioritized for further investigation. We demonstrated it was significantly elevated in senescent vascular cells, aged arteries, and early atherosclerosis. In vitro experiments showed that CST3 enhances the monocyte-endothelial cell adhesion. Additionally, ligand-receptor pairing analyses revealed two important pathways, COL4A1-ITGA1 and LPL-LRP1 pathways, linked to the critical processes in the development of atherosclerosis, including cell adhesion, inflammation response, extracellular matrix organization, and lipid metabolism. We further demonstrated a reduced monocyte-endothelial cell adhesion following the knockdown of COL4A1 or ITGA1 and a significantly increased expression of COL4A1, ITGA1, and LPL in arterial intima of aged mice and ApoE-/- mice. Our findings demonstrate that vascular cell-derived SASP proteins increase the CAD susceptibility and identify CST3 functionally contributing to atherosclerosis.

Activation of moderate autophagy promotes survival of fat graft.

Clinically unpredictable retention following fat grafting remains outstanding problems because of the unrevealed mechanism of grafted fat survival. The role of autophagy, a process to maintain cellular homeostasis through recycling cellular debris, has yet been to be reported in fat grafting. This study aims to improve the survival of fat grafting through the autophagy. First, the relationship between cell death and autophagy in the early stage of fat grafting was evaluated through immunostaining, RNA sequencing, and western blot. Next, rapamycin, an autophagic agonist, was used for the culturing of adipose-derived stem cells and adipocytes during ischemia. Cell death, autophagy, and reactive oxygen species (ROS) were assayed. Finally, rapamycin was used to assist fat grafting in nude mice. The results demonstrated that the peak of cell death at the early stage of fat grafting was accompanied by a decrease in autophagy. In vitro, during ischemia, 25 nM was confirmed as the optimal dose of rapamycin that reduces cell death with enhanced autophagy and mitophagy, improved mitochondrial quality as well as decreased ROS accumulation. In vivo, promoted mitophagy, alleviated oxidative stress, and decreased cell apoptosis of rapamycin-treated fat grafts were observed in the early stage. In addition, rapamycin increased the survival of fat grafts with increased neovascularization and reduced fibrosis. We suggested that moderate autophagy induced by rapamycin contribute to enhanced ischemic tolerance and long term survival of fat grafts through mitochondrial quality control.

Identifying Noble Metal Catalysts for the Hydrogenation and Dehydrogenation of Dibenzyltoluene: A Combined Theoretical-Experimental Study.

We present a comprehensive theoretical and experimental investigation of the hydrogenation and dehydrogenation of dibenzyltoluene (DBT) using Pd-, Pt-, Ru-, and Rh-supported metal catalysts to identify the optimal catalysts for hydrogen storage and release processes. Our results demonstrated significant variation in the catalytic activity of the metal catalysts. 5 wt % Rh/Al2O3 and 5 wt % Pt/Al2O3 showed the highest activity for hydrogenation and dehydrogenation with the highest selectivity and turnover frequency (TOF), respectively. Conversely, 5 wt % Pd/Al2O3 and 5 wt % Ru/Al2O3 exhibited lower catalytic activity toward full hydrogenation and dehydrogenation. Rh/Al2O3 showed the best catalytic hydrogenation activity with a TOF of 26.49 h-1 and a hydrogenation degree of 92.69% in 2 h, while Pt/Al2O3 exhibited the best catalytic dehydrogenation activity with a released H2 volume of 3755 mL, a dehydrogenation degree of 78.23%, and a TOF of 39.56 h-1 in 2 h. Additionally, we estimated the activation energies for hydrogenation and dehydrogenation to be 67.20 and 82.78 kJ/mol, respectively. Notably, the produced hydrogen gas was of high purity and suitable for use in fuel cells. Density functional theory (DFT) calculations were used to analyze the adsorption structure and reaction energy changes of all intermediate products of DBT on the surface of the chosen catalysts. Our research provides valuable insights into developing efficient catalysts for liquid organic hydrogen carriers.

Vascular Aging: Assessment and Intervention.

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

Convergence Rates for the Constrained Sampling via Langevin Monte Carlo.

Sampling from constrained distributions has posed significant challenges in terms of algorithmic design and non-asymptotic analysis, which are frequently encountered in statistical and machine-learning models. In this study, we propose three sampling algorithms based on Langevin Monte Carlo with the Metropolis-Hastings steps to handle the distribution constrained within some convex body. We present a rigorous analysis of the corresponding Markov chains and derive non-asymptotic upper bounds on the convergence rates of these algorithms in total variation distance. Our results demonstrate that the sampling algorithm, enhanced with the Metropolis-Hastings steps, offers an effective solution for tackling some constrained sampling problems. The numerical experiments are conducted to compare our methods with several competing algorithms without the Metropolis-Hastings steps, and the results further support our theoretical findings.

[Effects of Biochar Application on Soil Bacterial Community Diversity and Winter Wheat Growth in Wheat Fields].

A long-term field experiment was conducted to study the diversity of soil bacterial communities and the response of crop growth to biochar application, in order to provide a scientific basis for the rational application of biochar in agricultural fields. Four treatments were applied at 0 (B0 blank), 5 (B1), 10 (B2), and 20 t·hm-2(B3) to investigate the effects of biochar on soil physical and chemical properties, soil bacterial community diversity, and growth of winter wheat using Illumina MiSeq high-throughput sequencing technology. The results showed that soil water content, pH value, soil organic carbon, total nitrogen, nitrate nitrogen content, winter wheat biomass, nitrogen uptake, and yield showed an increasing trend with the increase in biochar amount. The high-throughput sequencing results showed that the B2 treatment significantly reduced the alpha diversity of the bacterial community at the flowering stage. The overall response of soil bacterial community composition to different application rates of biochar and phenological phases was taxonomically consistent. In this study, Proteobacteria, Acidobacteria, Planctomycetes, Gemmatimonadetes, and Actinobacteria were the dominant bacterial phyla. The relative abundance of Acidobacteria decreased, but the relative abundance of Proteobacteria and Planctomycetes increased with biochar application. The results of redundancy analysis, co-occurrence network analysis, and PLS-PM analysis indicated that bacterial community compositions were closely associated with soil parameters such as soil nitrate and total nitrogen. The average connectivity between 16S OTUs was higher under the B2 and B3 treatments (16.966 and 14.600) than under the B0 treatment. The variation in soil bacterial community (89.1%) was regulated by biochar and sampling period and partly explained the changes in the growth dynamics of winter wheat (0.077). In conclusion, biochar application could regulate the changes in the soil bacterial community and promote crop growth after seven years of application. It is suggested that 10-20 t·hm-2 biochar should be applied in semi-arid agricultural areas to achieve sustainable agricultural development.

Exosomes with overexpressed miR 147a suppress angiogenesis and infammatory injury in an experimental model of atopic dermatitis.

Atopic dermatitis is defined as an intensely systemic inflammation among skin diseases. Exosomes derived from adipose-derived stem cells may be a novel cell-free therapeutic strategy for atopic dermatitis treatment. This study aims to elucidate the possible underlying mechanism of adipose-derived stem cells-exosomes harboring microRNA-147a in atopic dermatitis pathogenesis. BALB/c mice treated with Dermatophagoides farinae extract/2,4-dinitrochlorobenzene were defined as a mouse model of atopic dermatitis, either with inflamed HaCaT cells and HUVECs exposed with TNF-α/IFN-γ stimulation were applied for a cell model of atopic dermatitis. The concentrations of IL-1ß and TNF-α in the supernatants were examined by ELISA. Cell viability and migration were assessed by MTT and Transwell assay. The apoptosis was examined using flow cytometry and TUNEL staining. The tube formation assay was employed to analyzed angiogenesis. The molecular regulations among miR-147a, MEF2A, TSLP and VEGFA were confirmed using luciferase reporter assay, either with ChIP. microRNA-147a was markedly downregulated in the serum and skin samples of atopic dermatitis mice, of which overexpression remarkably promoted HaCaT cell proliferation, meanwhile inhibiting inflammatory response and cell apoptosis. microRNA-147a in adipose-derived stem cells was subsequently overexpressed, and exosomes (Exos-miR-147a mimics) were collected. Functionally, exos-microRNA-147a mimics attenuated TNF-α/IFN-γ-induced HaCaT cell inflammatory response and apoptosis, and suppressed HUVECs angiogenesis. Encouraging, molecular interaction experiments revealed that exosomal microRNA-147a suppressed TNF-α/IFN-γ-induced HUVECs angiogenesis by targeting VEGFA, and exosomal microRNA-147a repressed HaCaT cells inflammatory injury through the MEF2A-TSLP axis. Mechanistically, exosomal microRNA-147a repressed pathological angiogenesis and inflammatory injury during atopic dermatitis progression by targeting VEGFA and MEF2A-TSLP axis. microRNA-147a-overexpressing adipose-derived stem cells-derived exosomes suppressed pathological angiogenesis and inflammatory injury in atopic dermatitis by targeting VEGFA and MEF2A-TSLP axis.

Adipose-Derived Stem Cell Extracellular Vesicles Improve Wound Closure and Angiogenesis in Diabetic Mice.

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.

Extracellular Vesicles Isolated From Hypoxia-Preconditioned Adipose-Derived Stem Cells Promote Hypoxia-Inducible Factor 1α-Mediated Neovascularization of Random Skin Flap in Rats.

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 × 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.

Recent advances in hydrothermal synthesis of facet-controlled CeO2-based nanomaterials.

CeO2-based nanomaterials have received tremendous attention due to their variety of applications. This paper is focused on the recent advances in facet-controlled CeO2-based nanomaterials by the hydrothermal method. CeO2-based nanomaterials with controllable size and exposed facets can be prepared by adjusting the reaction parameters. Moreover, doping and loading metals can improve the oxygen storage capacity (OSC) of CeO2 and its catalytic activity. Various research studies on catalytic applications such as CO oxidation, water-gas shift reaction (WGSR), decomposition of hydrocarbons, and photocatalytic reaction have been carried out to exhibit the high potential of facet-controlled CeO2 nanomaterials. This review will provide readers with various ideas for facet-controlled CeO2-based nanomaterials.

Extracellular Vesicles Derived from Adipose-Derived Stem Cells Accelerate Diabetic Wound Healing by Suppressing the Expression of Matrix Metalloproteinase-9.

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 whether 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 effects of ADSC-EVs on healing, re-epithelialisation, collagen deposition, and MMP-9 concentration in diabetic wound fluids were 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 possess the potential of 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.

Preparing Adipogenic Hydrogel with Neo-Mechanical Isolated Adipose-Derived Extracellular Vesicles for Adipose Tissue Engineering.

BACKGROUND: Subcutaneous transplantation of decellularized adipose tissue was capable of recellularization during soft tissue repair. However, further improvements are required to promote angiogenesis and adipogenesis. Here, the authors proposed a neo-mechanical protocol to isolate adipose tissue-derived extracellular vesicles (ATEVs) through lipoaspirate as a mediator for both angiogenesis and adipogenesis, and prepared ATEV-rich decellularized adipose tissue hydrogel for adipose tissue engineering. METHODS: Adipose liquid extract and lipid-devoid adipose tissue were extracted through homogenization and repeated freeze and thaw cycles. ATEVs were isolated from adipose liquid extract by ultracentrifugation. Decellularized adipose tissue hydrogel was prepared by optimized decellularization of lipid-devoid adipose tissue. The optimum dose of ATEVs for angiogenesis and adipogenesis was estimated by co-culturing with vascular endothelial cells and 3T3-L1 cells, then mixed with the hydrogel. ATEV-enriched hydrogel was injected subcutaneously into the back of severe combined immunodeficiency mice, and then subjected to supplementary injection of ATEVs on postoperative day 14. ATEV-free decellularized adipose tissue hydrogel was injected as control. The newly formed tissue samples were harvested at postoperative weeks 2, 4, and 8 and subjected to volume measurement, hematoxylin and eosin staining, and immunofluorescence (CD31 and perilipin) staining. RESULTS: The optimum dose of ATEVs for promoting angiogenesis and adipogenesis was 50 µg/ml. The newly formed tissue mediated by ATEV-enriched hydrogel had increased volume well as improved angiogenesis and adipogenesis at postoperative week 4 and 8. CONCLUSION: ATEV-enriched adipogenic hydrogel promotes enhanced angiogenesis and adipogenesis and could serve as a promising biomaterial for adipose tissue engineering.

Homotopic Gradients of Generative Density Priors for MR Image Reconstruction.

Deep learning, particularly the generative model, has demonstrated tremendous potential to significantly speed up image reconstruction with reduced measurements recently. Rather than the existing generative models that often optimize the density priors, in this work, by taking advantage of the denoising score matching, homotopic gradients of generative density priors (HGGDP) are exploited for magnetic resonance imaging (MRI) reconstruction. More precisely, to tackle the low-dimensional manifold and low data density region issues in generative density prior, we estimate the target gradients in higher-dimensional space. We train a more powerful noise conditional score network by forming high-dimensional tensor as the network input at the training phase. More artificial noise is also injected in the embedding space. At the reconstruction stage, a homotopy method is employed to pursue the density prior, such as to boost the reconstruction performance. Experiment results implied the remarkable performance of HGGDP in terms of high reconstruction accuracy. Only 10% of the k-space data can still generate image of high quality as effectively as standard MRI reconstructions with the fully sampled data.

Supplementation with Extracellular Vesicles Derived from Adipose-Derived Stem Cells Increases Fat Graft Survival and Browning in Mice: A Cell-Free Approach to Construct Beige Fat from White Fat Grafting.

BACKGROUND: Growing evidence has demonstrated that adipose-derived stem cell-derived extracellular vesicles enhance the survival of fat grafts and the browning of white adipose tissue. We evaluated whether supplementation with adipose-derived stem cell-derived extracellular vesicles promotes the survival and browning of fat grafts. METHODS: Extracellular vesicles derived from adipose-derived stem cells were injected into fat grafts of C57BL/6 mice once per week until postgraft week 12. The grafts were collected and weighed after postgraft weeks 2, 4, and 12. The histological morphology, neovascularization, and the proportion of M2 macrophages of grafts were evaluated. The ability of extracellular vesicles to promote macrophage polarization and catecholamine secretion was detected. Whether the inducement of browning adipose differentiation is extracellular vesicles or the paracrine effect of M2 macrophages polarized by extracellular vesicles was also verified. RESULTS: Grafts treated by extracellular vesicles derived from adipose-derived stem cells showed enhanced beige adipose regeneration with increased neovascularization, M2 macrophage proportion, and norepinephrine secretion at postgraft week 4. Increased retention and decreased fibrosis and necrosis were noted at postgraft week 12. The extracellular vesicles uptake by macrophages promoted M2 type polarization and catecholamine secretion while suppressing M1 type polarization. Of note, browning adipose differentiation with enhanced energy expenditure could be promoted only by the conditioned medium from extracellular vesicle-polarized M2 macrophages but not by extracellular vesicles themselves. CONCLUSIONS: Supplementation with extracellular vesicles derived from adipose-derived stem cells increases fat graft survival and browning by which extracellular vesicles-polarized M2 macrophages secrete catecholamines to promote beige adipose regeneration.

Extracellular Vesicles Derived From Human Adipose-Derived Stem Cell Prevent the Formation of Hypertrophic Scar in a Rabbit Model.

BACKGROUND: Preventing scar formation during wound healing has important clinical implications. Numerous studies have indicated that adipose-derived stem cell culture mediums, which are rich in cytokines and extracellular vesicles (EVs), regulate matrix remodeling and prevent scar formation after wound healing. Therefore, using a rabbit scar model, we tried to demonstrate which factor in adipose-derived stem cell culture mediums plays a major role in preventing scar formation (EVs or cytokines), as well as revealing the underlying mechanism. METHODS: Human adipose-derived stem cells (hASCs) were isolated from the subcutaneous adipose tissue of a healthy female donor. The surface CD markers of third-passage hASCs were analyzed by flow cytometry. The adipogenic differentiation capacity of the hASCs was detected using Oil O staining. A cultured medium of third- to five-passage hASCs was collected for EV and EV-free medium isolations. Extracellular vesicles were characterized using transmission electron microscopy, NanoSight, and the Western blotting for surface markers CD63, TSG101, and Alix. The EV-free medium was characterized by Western blotting for vascular endothelial growth factor A (VEGFA), platelet derived growth factor B (PDGFB), and transforming growth factor ß 1 (TGFß1). Eight-millimeter-diameter wounds were created on the ventral side of both ears of 16 New Zealand rabbits. A total of 0.1 mL of the human adipose-derived stem cell-extracellular vesicle (hASC-EV) or EV-free medium was locally injected into wounds made on the right ears during wound healing. Meanwhile, equal amounts of phosphate buffer saline were injected into the left ears as a control. Biopsies of the wounded skin and surrounding tissue were excised on postoperative day 28 and subjected to hematoxylin and eosin (H&E), Masson, and α-SMA immunofluorescence staining. The protein expression of α-SMA and collagen I in both scar tissues and the normal skin were evaluated via Western blotting. RESULTS: The hASCs expressed high levels of 49d, CD90, CD105, and CD73 but did not express CD34 or CD45. The hASCs differentiated into adipocytes under an adipogenic induction medium. Under transmission electron microscopy, the hASC-EVs were circular, bilayer membrane vesicles and approximately 95% of the particles were between 50 and 200 nm in size. The hASC-EVs expressed the same surface markers as EVs, including CD63, TSG101, and Alix and displayed little expression of VEGFA, PDGFB, and TGFß1. The EV-free medium had a high expression of VEGFA, PDGFB, and TGFß1 but displayed no expression of CD63, TSG101, and Alix. In vivo, the hASC-EV treatment prevented the formation of hypertrophic scars on postoperative day 28 and suppressed collagen deposition and myofibroblast aggregation. However, the EV-free medium did not prevent the formation of hypertrophic scars on the same time point and had little effect on collagen deposition and myofibroblast aggregation when compared with the control group. CONCLUSIONS: Our study suggests that hASCs are associated with preventive scar formation therapy because of paracrine EVs rather than cytokines. A local injection of hASC-EVs during wound healing efficiently prevented hypertrophic scar formation, which may have a clinically beneficial antiscarring effect.

Extracellular vesicles derived from human adipose-derived stem cells promote the exogenous angiogenesis of fat grafts via the let-7/AGO1/VEGF signalling pathway.

Extracellular vesicles (EVs) derived from human adipose-derived stem cells (hADSCs) possess the proangiogenic potential for ischaemic diseases. Thus, our study aimed to evaluate the therapeutic effects of hADSC-EVs on fat grafting and explore the mechanism of hADSC-EVs promoting angiogenesis. The EVs released by hADSCs incubated under normal or hypoxic conditions were employed to supplement fat grafting in a nude mouse model. The proliferation, migration, tube formation and vascular endothelial growth factor (VEGF) secretion of vascular endothelial cells co-cultured with two kinds of hADSC-EVs were analysed. MicroRNA sequencing was performed to reveal the species and content of microRNAs in hADSC-EVs, the key microRNAs were blocked, and their effect in promoting angiogenesis was detected via above protocols as a reverse proof. The results demonstrate that hADSC-EVs could improve the survival of fat grafts by promoting exogenous angiogenesis and enhance the proliferation, migration, tube formation and VEGF secretion of vascular endothelial cells. In addition, the pro-angiogenic effect of hADSC-EVs in vivo and vitro could be enhanced by hypoxic pre-treatment. We found that the let-7 family, a kind of hypoxic-related microRNA, is enriched in hypoxic hADSC-EVs that contribute to angiogenesis via the let-7/argonaute 1 (AGO1)/VEGF signalling pathway.

[Effect of circulating estrogen level on the outcome of free fat grafting in nude mice].

OBJECTIVE: To investigate the effect of circulating estrogen level on the outcome of free fat grafting in nude mice. METHODS: Eighteen female nude mice aged 6-8 weeks (weighing, 20-25 g) were randomly divided into 3 groups ( n=6). The nude mice in the ovariectomized group were treated with ovariectomy. The nude mice in the high estrogen group and the normal estrogen group only made the same incision to enter the peritoneum without ovariectomy. The nude mice in the high estrogen group were given the estradiol (0.2 mg/g) every 3 days for 30 days. The other two groups were given the same amount of PBS every 3 days. At 30 days after operation, the tail vein blood of nude mice in 3 groups were detected by estradiol ELISA kit, and the free fat (0.3 mL) donated by the females was injected into the sub-scalp of nude mice. After 8 weeks of fat grafting, the samples were taken for gross observation and weighing, and the prepared slices were stained with HE staining, CD31-perilipin fluorescence staining, immunohistochemical staining of uncoupling protein 1 (UCP1), and immunofluorescence staining of estrogen receptor α. The diameter of adipocytes and vascular density of adipose tissue were measured. The mRNA expressions of UCP1 and estrogen receptor α were detected by realtime fluorescence quantitative PCR (qRT-PCR). RESULTS: All nude mice survived during experiment. ELISA test showed that the concentration of estradiol significantly decreased in the ovariectomized group and increased in the high estrogen group compared with the normal estrogen group ( P<0.05). At 8 weeks after fat grafting, the graft volume from large to small was ovariectomized group, normal estrogen group, and high estrogen group. There was significant difference in wet weight between the ovariectomized group and high estrogen group ( P<0.05). Section staining showed that compared with the normal estrogen group, the adipocytes in the ovariectomized group were larger, the expression of peri-lipoprotein was weaker, the vascular density decreased, and the expressions of UCP1 was negative, and the estrogen receptor α positive cells reduced. The above observation results in the high estrogen group were contrary to those in the ovariectomized group. There were significant differences in the diameter of adipocytes, the vascular density of adipose tissue, the number of the estrogen receptor α positive cells between groups ( P<0.05). The results of qRT-PCR showed that the mRNA expressions of UCP1 and estrogen receptor α significantly increased in the high estrogen group and decreased in the ovariectomized group compared with the normal estrogen group, and the differences were significant ( P<0.05). CONCLUSION: The level of circulating estrogen has a significant effect on the outcome of free fat grafting in nude mice. Low estrogen level leads to hypertrophy of graft adipocytes, while high estrogen level leads to the production of a large amount of beige fat and high vascular density in fat grafts, which may be related to the activation of estrogen receptor α on adipocytes.