Adenosine accelerates the healing of diabetic ischemic ulcers by improving autophagy of endothelial progenitor cells grown on a biomaterial

Enhancing wound healing via modulation of autophagy-induced apoptosis: the role of nicotinamide riboside and resveratrol in streptozotocin-treated diabetic rat

Impaired wound healing from diabetes mellitus (DM) causes lower limb amputations, posing clinical, social, and economic issues. Hypoxia and advanced glycation end products cause autophagy and apoptosis dysregulation, which delays wound healing. The study will test systemic and topical Nicotinamide Riboside (NR) and Resveratrol (RSV) for the capacity to modulate autophagy and apoptosis via the SIRT-1-FOXO1 pathway and improve diabetic wound healing. About 54 male Sprague-Dawley rats were separated into control, diabetic (T1D), T1D-Gel-Base, T1D-NR, T1D-RSV, and T1D-NR+RSV groups. Rats were gavaged with 50 mg/kg/day RSV and 300 mg/kg/day NR for 5 weeks before having their wounds topically treated with 5% NR and RSV gel for 15 days after diabetes induction. Biochemical, histomorphometric, and stereological assays were conducted. The mRNA expressions of SIRT-1, FOXO1, VEGF, BAX, Cas3, Bcl-2, Beclin1, LC3IIβ, P62, and ATG5 were examined by qRT-PCR. NR and RSV improved diabetic rat wound closure. Diabetic rats treated with NR and RSV had significantly higher LC3IIβ, VEGEF, Bcl-2, and SIRT-1 mRNA levels. Bcl-2, p62, and ATG5 were regulated whereas BAX and Cas 3 were reduced. Stereological investigations showed epidermal, dermal, collagen bundle, vascular, and fibroblast density enhancements. This study highlights the potential of NR and RSV, acting as SIRT-1 activators, in improving diabetic wound healing by regulating SIRT-1-FOXO1-mediated autophagy and apoptosis. These findings offer valuable insights for developing targeted strategies to enhance diabetic wound healing. The combination of NR and RSV showed promising effects, suggesting a potential therapeutic approach for improving diabetic wound healing.

The Expression of Circ-Astn1 Inhibits High Glucose Induced Endothelial Progenitor Cell Dysfunction by Activating Autophagy

BACKGROUND

Diabetes mellitus (DM) and complications such as chronic kidney disease and cardiovascular symptoms pose a substantial public health burden. Increasing studies have shown that circular RNAs (circRNAs) regulate many gene expressions that are essential in diverse pathological and biological procedures. However, the roles of particular circRNAs in DM are unclear.

METHODS

In the current investigation, endothelial progenitor cells (EPCs) were used to search for abnormal expression of circRNAs by using high-throughput sequencing under high glucose (HG) conditions. The regulatory mechanisms and targets were then studied through bioinformatics analysis, luciferase reporter analysis, angiogenic differentiation experiments, flow cytometry detection of apoptosis and RT-qPCR analysis.

RESULTS

The circ-Astn1 expression in EPCs decreased after HG treatment. Overexpression or circ-Astn1 suppressed HG induced endothelial cell damage. MicroRNA (miR)-138-5p and SIRT5 were found to be the downstream targets of circ-Astn1 through luciferase reporter analysis. SIRT5 downregulation or miR-138-5p overexpression reversed circ-Astn1's protective effect against HG induced endothelial cell dysfunction, including apoptosis and abnormal vascular differentiation. Furthermore, circ-Astn1 overexpression promoted autophagy activation by increasing SIRT5 expression under HG conditions. Our findings suggest that circ-Astn1 mediated promotion of SIRT5 facilitates autophagy by sponging miR-138-5p.

CONLUSION

Together, our findings show that the overexpression of circ-Astn1 suppresses HG induced endothelial cell damage by targeting miR-138-5p/SIRT5 axis.

Integration of Zn2+, ATP, and bFGF to Nanodressing with Core-Shell Structure Fabricated by Emulsion Electrospinning for Wound Healing

Basic fibroblast growth factor (bFGF) plays an important role in active wound repair. However, the existing dosage forms in clinical applications are mainly sprays and freeze-dried powders, which are prone to inactivation and cannot achieve a controlled release. In this study, a bioactive wound dressing named bFGF-ATP-Zn/polycaprolactone (PCL) nanodressing with a "core-shell" structure was fabricated by emulsion electrospinning, enabling the sustained release of bFGF. Based on the coordination and electrostatic interactions among bFGF, ATP, and Zn2+, as well as their synergistic effect on promoting wound healing, a bFGF-ATP-Zn ternary combination system was prepared with higher cell proliferation activity and used as the water phase for emulsion electrospinning. The bFGF-ATP-Zn/PCL nanodressing demonstrated improved mechanical properties, sustained release of bFGF, cytocompatibility, and hemocompatibility. It increased the proliferation activity of human dermal fibroblasts (HDFs) and enhanced collagen secretion by 1.39 and 3.45 times, respectively, while reducing the hemolysis rate to 3.13%. The application of the bFGF-ATP-Zn/PCL nanodressing in mouse full-thickness skin defect repair showed its ability to accelerate wound healing and reduce wound scarring within 14 days. These results provide a research basis for the development and application of this bioactive wound dressing product.

Autophagy-Modulated Biomaterial: A Robust Weapon for Modulating the Wound Environment to Promote Skin Wound Healing

Autophagy, a self-renewal mechanism, can help to maintain the stability of the intracellular environment of organisms. Autophagy can also regulate several cellular functions and is strongly related to the onset and progression of several diseases. Wound healing is a biological process that is coregulated by different types of cells. However, it is troublesome owing to prolonged treatment duration and poor recovery. In recent years, biomaterials have been reported to influence the skin wound healing process by finely regulating autophagy. Biomaterials that regulate autophagy in various cells involved in skin wound healing to regulate the differentiation, proliferation and migration of cells, inflammatory responses, oxidative stress and formation of the extracellular matrix (ECM) have emerged as a key method for improving the tissue regeneration ability of biomaterials. During the inflammatory phase, autophagy enhances the clearance of pathogens from the wound site and leads to macrophage polarization from the M1 to the M2 phenotype, thus preventing enhanced inflammation that can lead to further tissue damage. Autophagy plays important roles in facilitating the formation of extracellular matrix (ECM) during the proliferative phase, removing excess intracellular ROS, and promoting the proliferation and differentiation of endothelial cells, fibroblasts, and keratinocytes. This review summarizes the close association between autophagy and skin wound healing and discusses the role of biomaterial-based autophagy in tissue regeneration. The applications of recent biomaterials designed to target autophagy are highlighted, including polymeric materials, cellular materials, metal nanomaterials, and carbon-based materials. A better understanding of biomaterial-regulated autophagy and skin regeneration and the underlying molecular mechanisms may open new possibilities for promoting skin regeneration. Moreover, this can lay the foundation for the development of more effective therapeutic approaches and novel biomaterials for clinical applications.

17β-Estradiol promotes angiogenesis of bone marrow mesenchymal stem cells by upregulating the PI3K-Akt signaling pathway

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The role and mechanism of 17β -estradiol in the regulation of BMSC promoting angiogenesis were analyzed by bioinformatics techniques for the first time.

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Combined with FN1, MCM2, XPO1, NTRK1 and other proteins, 17β-estradiol is able to activate PI3K-Akt, MAPK and other signaling pathways to regulate BMSCs to promote or remodel angiogenesis.

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17β-estradiol upregulates the PI3K-Akt signaling pathway to promote the BMSC angiogenesis process of differentiation.

Objective

Estrogen is an important hormone affecting angiogenesis in women and is important for female physical development. Menopausal women are prone to serious cardiovascular and cerebrovascular diseases when estrogen is significantly reduced. Bone marrow mesenchymal stem cells (BMSC) have potential roles in processes such as angiogenesis and remodeling. This study is to investigate the effect of 17β-estradiol on BMSC angiogenic differentiation and its underlying molecular mechanism, and to provide a basis for the treatment of microvascular diseases.

Methods

Enrichment analysis of apoptosis, migration or angiogenesis processes and molecular mechanisms of BMSC treated with 17β-estradiol was performed to screen core proteins and perform molecular docking validation. Human MSCs were cultured in vitro to examine the effect of 17β-estradiol on BMSC migration or angiogenic differentiation.

Results

17β-estradiol acted on 48 targets of BMSC and was involved in regulating 52 cell migration processes or 17 angiogenesis processes through 66 KEGG pathways such as PI3K-Akt, MAPK, etc. 17β-estradiol bound tightly to 10 core proteins including APP, NTRK1, EGFR, and HSP90AA1. 17β-estradiol promoted cell scratch area closure rate and CD31 expression in BMSCs, downregulated BMSC apoptosis rate, and promoted Akt and p-Akt protein expression in BMSC.

Conclusion

17β-estradiol binds to FN1, MCM2, XPO1, NTRK1 and other proteins to initiate PI3K-Akt, MAPK and other signaling pathways, so as to regulate BMSC to promote or remodel angiogenesis, verifying that 17β-estradiol up-regulates PI3K-Akt signaling pathway to promote BMSC angiogenic differentiation.

The Inhibitory Effect of Regulatory T Cells on the Intimal Hyperplasia of Tissue-Engineered Blood Vessels in Diabetic Pigs

Severe inflammatory response and functional impairment of endothelial progenitor cells (EPCs) often lead to the implantation failure of EPC-captured tissue-engineered blood vessels (TEBVs) in diabetes. Regulatory T cells (Treg cells) are the most important inhibitory immune cells, but their effects in angiogenesis remain undefined, and the differences in the microenvironment may be an important reason. Here, we constructed a TEBV coated with an anti-CD34 antibody-functionalized heparin-collagen multilayer (anti-CD34 antibody-modified TEBV) using layer-by-layer self-assembly. Then, TEBVs were implanted into diabetic pigs. All TEBVs remained unobstructed 60 days after implantation, although varying degrees of intimal hyperplasia were detectable. Severe intimal hyperplasia was observed in the control group and peripheral injection of Treg cells group. Intravenous injection of Treg cells significantly inhibited intimal hyperplasia, inflammation, and cell apoptosis. Moreover, intravenous injection increased the proportion of circulating EPCs, while peripheral injection did not have these effects and reduced microvessel density around the TEBV. Interestingly, many Nestin+ cells could be detected in TEBVs, most of which were fusiform, showing the characteristics of smooth-muscle cells. Treg cell intravenous transplantation markedly reduced the number of Nestin+ cells in the TEBV. In conclusion, Treg cells inhibited the intimal hyperplasia of TEBVs in diabetic pigs by promoting EPC mobilization, anti-inflammatory action, and cellular protection.

Limited Treatment Options for Diabetic Wounds: Barriers to Clinical Translation Despite Therapeutic Success in Murine Models

Significance: Millions of people worldwide suffer from diabetes mellitus and its complications, including chronic diabetic wounds. To date, there are few widely successful clinical therapies specific to diabetic wounds beyond general wound care, despite the vast number of scientific discoveries in the pathogenesis of defective healing in diabetes. Recent Advances: In recent years, murine animal models of diabetes have enabled the investigation of many possible therapeutics for diabetic wound care. These include specific cell types, growth factors, cytokines, peptides, small molecules, plant extracts, microRNAs, extracellular vesicles, novel wound dressings, mechanical interventions, bioengineered materials, and more. Critical Issues: Despite many research discoveries, few have been translated from their success in murine models to clinical use in humans. This massive gap between bench discovery and bedside application begs the simple and critical question: what is still missing? The complexity and multiplicity of the diabetic wound makes it an immensely challenging therapeutic target, and this lopsided progress highlights the need for new methods to overcome the bench-to-bedside barrier. How can laboratory discoveries in animal models be effectively translated to novel clinical therapies for human patients? Future Directions: As research continues to decipher deficient healing in diabetes, new approaches and considerations are required to ensure that these discoveries can become translational, clinically usable therapies. Clinical progress requires the development of new, more accurate models of the human disease state, multifaceted investigations that address multiple critical components in wound repair, and more innovative research strategies that harness both the existing knowledge and the potential of new advances across disciplines.

Nerve growth factor enhances the therapeutic effect of mesenchymal stem cells on diabetic periodontitis

Patients with diabetes frequently suffer from periodontitis, which progresses rapidly and is difficult to cure. Mesenchymal stem cell (MSC) transplantation may effectively treat periodontitis, but high glucose limits its therapeutic effect in diabetes. Nerve growth factor (NGF) has the functions of cell protection, anti-apoptosis and immune regulation, and may have potential application in diabetic periodontitis. In the present study, flow cytometry indicated that NGF inhibited MSC apoptosis induced by high glucose. Of note, high glucose promoted the transformation of MSCs into the proinflammatory type. NGF inhibited this transformation of MSCs under diabetic conditions and further decreased the proportion of T cells and monocytes/macrophages among lymphocytes. An animal model of diabetic periodontitis was constructed and MSC transplantation was demonstrated to reduce alveolar bone loss caused by diabetes. NGF enhanced the therapeutic effect of MSCs and maintained transplanted MSC survival in periodontal tissue of diabetic mice. Immunohistochemical analysis of periodontal tissues suggested that in the NGF group, infiltration of T cells and macrophages was reduced. Neurotrophic receptor tyrosine kinase 1 was indicated to have a key role in these effects of NGF. In conclusion, NGF may enhance the therapeutic effect of MSCs on diabetic periodontitis by protecting the cells and promoting the transformation of MSCs into the immunosuppressive type.

Enhanced autophagy promotes the clearance of Pseudomonas aeruginosa in diabetic rats with wounds

Background

To investigate the effects of the Pseudomonas aeruginosa (P. aeruginosa) type 3 secretion system (T3SS) on diabetic wound healing and autophagy-associated proteins.

Methods

P. aeruginosa and P. aeruginosa without T3SS were used to infect back wounds in 36 rats (18 normal and 18 diabetic). Followed infection with P. aeruginosa, another 36 rats (18 normal and 18 diabetic) with back wounds were treated with autophagy inducer rapamycin or gentamicin (positive control). Wound healing, colony count, HE and Masson staining were recorded. Western blot and immunofluorescent were used to determine the expression of the autophagy markers (LC3, beclin-1 and p62) in wound tissues.

Results

The number of P. aeruginosa colonies in infected wounds began to decrease on day 3 in normal rats and on day 7 in diabetic rats. The decrease was more apparent in P. aeruginosa without T3SS. The expression of LC3-II/LC3-I and beclin-1 gradually increased, and p62 gradually decreased in the wounds in of all groups; however, the changes were more dramatic in normal rats compared with diabetic rats on day 14. Rapamycin increased LC3-II/LC3-I and beclin-1 expression, and decreased p62 expression, gentamicin had no effect on their expression of autophagy markers.

Conclusions

T3SS of P. aeruginosa inhibited the entire autophagy process in wounds. Thus inducing autophagy could enhance the clearance of P. aeruginosa in diabetic wounds and is expected to become a new method of anti-P. aeruginosa infection.

CD150highTreg cells may attenuate graft versus host disease and intestinal cell apoptosis after hematopoietic stem cell transplantation

Combined transplantation of regulatory T cells (Treg cells) may significantly attenuate graft versus host disease (GVHD) after hematopoietic stem cell transplantation (HSCT). Recent studies indicated that CD150+Treg cells could secret adenosine to maintain the quiescent status of HSCs. However, whether it is attributable to the attenuation of GVHD after HSCT is still unclear. In vitro studies revealed that CD150+Treg cells induced immune tolerance was comparable to that induced by CD150-Treg cells, but CD150+Treg cells can secret more adenosine, increase P-AMPK expression and regulate energy metabolism to induce the proliferation of HSC proliferation and inhibit their differentiation into dendritic cells. In this study, GVHD animal model was established, and combined transplantation of Treg cells and HSCs was performed. Results showed the survival time was significantly prolonged, the proliferation rate of HSCs increased significantly and the proportion of undifferentiated HSCs elevated significantly after CD150+Treg transplantation as compared to CD150-Treg transplantation. Immunohistochemistry revealed CD150+Treg cells could secret adenosine, activate AMPK expression and inhibit intestinal cell apoptosis and inflammation after HSCT. Taken together, this study indicates CD150+Treg cells can regulate energy metabolism to attenuate GVHD and intestinal cell apoptosis after HSCT.

Distinct role of autophagy on angiogenesis: highlights on the effect of autophagy in endothelial lineage and progenitor cells

Autophagy plays a critical role in the dynamic growth of each cell through different conditions. It seems that this intracellular mechanism acts as a two-edged sword against the numerous cell insults. Previously, autophagy was described in the context of cell activity and behavior, but little knowledge exists related to the role of autophagy in endothelial cells, progenitors, and stem cells biology from different tissues. Angiogenic behavior of endothelial lineage and various stem cells are touted as an inevitable feature in the restoration of different damaged tissues and organs. This capacity was found to be dictated by autophagy signaling pathway. This review article highlights the fundamental role of cell autophagic response in endothelial cells function, stem cells dynamic, and differentiation rate. It seems that elucidation of the mechanisms related to pro- and/or anti-angiogenic potential of autophagy inside endothelial cells and stem cells could help us to modulate stem cell therapeutic feature post-transplantation.

Sitagliptin-mediated preservation of endothelial progenitor cell function via augmenting autophagy enhances ischaemic angiogenesis in diabetes

Recently, the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin, a major anti-hyperglycaemic agent, has received substantial attention as a therapeutic target for cardiovascular diseases via enhancing the number of circulating endothelial progenitor cells (EPCs). However, the direct effects of sitagliptin on EPC function remain elusive. In this study, we evaluated the proangiogenic effects of sitagliptin on a diabetic hind limb ischaemia (HLI) model in vivo and on EPC culture in vitro. Treatment of db/db mice with sitagliptin (Januvia) after HLI surgery efficiently enhanced ischaemic angiogenesis and blood perfusion, which was accompanied by significant increases in circulating EPC numbers. EPCs derived from the bone marrow of normal mice were treated with high glucose to mimic diabetic hyperglycaemia. We found that high glucose treatment induced EPC apoptosis and tube formation impairment, which were significantly prevented by sitagliptin pretreatment. A mechanistic study found that high glucose treatment of EPCs induced dramatic increases in oxidative stress and apoptosis; pretreatment of EPCs with sitagliptin significantly attenuated high glucose-induced apoptosis, tube formation impairment and oxidative stress. Furthermore, we found that sitagliptin restored the basal autophagy of EPCs that was impaired by high glucose via activating the AMP-activated protein kinase/unc-51-like autophagy activating kinase 1 signalling pathway, although an autophagy inhibitor abolished the protective effects of sitagliptin on EPCs. Altogether, the results indicate that sitagliptin-induced preservation of EPC angiogenic function results in an improvement of diabetic ischaemia angiogenesis and blood perfusion, which are most likely mediated by sitagliptin-induced prevention of EPC apoptosis via augmenting autophagy.

Construction of Antithrombotic Tissue-Engineered Blood Vessel via Reduced Graphene Oxide Based Dual-Enzyme Biomimetic Cascade

Thrombosis is one of the biggest obstacles in the clinical application of small-diameter tissue-engineered blood vessels (TEBVs). The implantation of an unmodified TEBV will lead to platelet aggregation and further activation of the coagulation cascade, in which the high concentration of adenosine diphosphate (ADP) that is released by platelets plays an important role. Inspired by the phenomenon that endothelial cells continuously generate endogenous antiplatelet substances via enzymatic reactions, we designed a reduced graphene oxide (RGO) based dual-enzyme biomimetic cascade to successively convert ADP into adenosine monophosphate (AMP) and AMP into adenosine. We used RGO as a support and bound apyrase and 5'-nucleotidase (5'-NT) on the surface of RGO through covalent bonds, and then, we modified the surface of the collagen-coated decellularized vascular matrix with the RGO-enzyme complexes, in which RGO functions as a platform with a large open surface area and minimal diffusion barriers for substrates/products to integrate two catalytic systems for cascading reactions. The experimental results demonstrate that the two enzymes can synergistically catalyze procoagulant ADP into anticoagulant AMP and adenosine successively under physiological conditions, thus reducing the concentration of ADP. AMP and adenosine can weaken or even reverse the platelet aggregation induced by ADP, thereby inhibiting thrombosis. Adenosine can also accelerate the endothelialization of TEBVs by regulating cellular energy metabolism and optimizing the microenvironment, thus ensuring the antithrombotic function and patency of TEBVs even after the RGO-enzyme complex loses its activity.

Sitagliptin Attenuates Endothelial Dysfunction of Zucker Diabetic Fatty Rats: Implication of the Antiperoxynitrite and Autophagy

Although the contributions of sitagliptin to endothelial function in diabetes mellitus were previously reported, the potential mechanisms still remain undefined. Our research was intended to explore the underlying mechanisms of protective effects of sitagliptin treatment on endothelial dysfunction in Zucker diabetic fatty (ZDF) rats. Male lean nondiabetic Zucker rats were used as control and male obese ZDF rats were randomly divided into ZDF and ZDF + sitagliptin groups. The significant decrease in endothelium-dependent relaxation induced by acetylcholine was observed in mesenteric arteries and thoracic aorta rings of ZDF rats. The administration of sitagliptin restored the vascular function effectively. The morphology study showed severe endothelial injuries in thoracic aortas of ZDF rats, and sitagliptin treatment attenuated these changes. The increased malondialdehyde levels and decreased superoxide dismutase activities in serum of ZDF rats were reversed by sitagliptin treatment. Sitagliptin also increased the expression of endothelial nitric oxide synthase and microtubule-associated protein 1 light chain 3 (LC3) and decreased the expression of inducible nitric oxide synthase, 3-nitrotyrosine, and p62 in ZDF rats. After giving Fe (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride porphyrin pentachloride (FeTMPyP, a peroxynitrite [ONOO^-] scavenger) or sitagliptin to high-glucose (30 mmol/L, 48 hours) cultured human umbilical vein endothelial cells (HUVECs), the increased levels of Beclin-1 and lysosome-associated membrane protein type 2 were detected. Both FeTMPyP and sitagliptin also significantly increased the number of mRFP-GFP-LC3 dots per cell, suggesting that autophagic flux was increased in HUVECs. Our study indicated that sitagliptin treatment can improve the endothelium-dependent relaxation and attenuate the endothelial impairment of ZDF rats. The protective effects of sitagliptin are possibly related to antiperoxynitrite and promoting autophagy.

Clinical application prospect of umbilical cord-derived mesenchymal stem cells on clearance of advanced glycation end products through autophagy on diabetic wound

Nowadays, wound healing delay due to diabetes is considered to be closely related to the accumulation of advanced glycation end products (AGEs). Although mesenchymal stem cells (MSCs) exhibit positive effects on diabetic wound healing, related mechanisms are still not fully elucidated. It has been reported that MSCs can improve the activity of autophagy in injured tissues, thereby playing an important role in wound healing. The autophagy induced by MSCs may be beneficial to diabetic wound healing via removing AGEs, which provide new ideas for clinical treatment of diabetic wounds with the potential of broad application prospects. In this study, the current research situation and application prospect of umbilical cord-derived MSCs on the clearance of AGEs in diabetic wound were reviewed.

An Overview on Current Issues and Challenges of Endothelial Progenitor Cell-Based Neovascularization in Patients with Diabetic Foot Ulcer

Diabetic foot ulcer's impaired wound healing, which leads to the development of chronic non-healing wounds and ultimately amputation, is a major problem worldwide. Although recently endothelial progenitor cell-derived cell therapy has been used as a therapeutic intervention to treat diabetic wounds, thereby promoting neovascularization, the results, however, are not satisfactory. In this article, we have discussed the several steps that are involved in the neovascularization process, which might be impaired during diabetes. In addition, we have also discussed the reported possible interventions to correct these impairments. Thus, we have summarized neovascularization as a process with a coordinated sequence of multiple steps and thus, there is the need of a combined therapeutic approach to achieve better treatment outcomes.