Angiogenic Factor AGGF1-Primed Endothelial Progenitor Cells Repair Vascular Defect in Diabetic Mice

Serum levels of AGGF1: Potential association with cutaneous and cardiopulmonary involvements in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by vasculopathy, aberrant immune activation, and extensive tissue fibrosis of the skin and internal organs. Because of the complicated nature of its pathogenesis, the underlying mechanisms of SSc remain incompletely understood. Angiogenic factor with a G-patch domain and a Forkhead-associated domain 1 (AGGF1) is a critical factor in angiogenesis expressed on vascular endothelial cells, associated with inflammatory and fibrotic responses. To elucidate the possible implication of AGGF1 in SSc pathogenesis, we investigated the association between serum AGGF1 levels and clinical manifestations in SSc patients. We conducted a cross-sectional analysis of AGGF1 levels in sera from 60 SSc patients and 19 healthy controls with enzyme-linked immunosorbent assay. Serum AGGF1 levels in SSc patients were significantly higher than those in healthy individuals. In particular, diffuse cutaneous SSc patients with shorter disease duration had higher levels compared to those with longer disease duration and limited cutaneous SSc patients. Patients with higher serum AGGF1 levels had a higher incidence of digital ulcers, higher modified Rodnan Skin Scores (mRSS), elevated serum Krebs von den Lungen-6 (KL-6) levels, C-reactive protein levels, and right ventricular systolic pressures (RVSP) on the echocardiogram, whereas they had reduced percentage of vital capacity (%VC) and percentage of diffusing capacity of the lungs for carbon monoxide (%DLCO) in pulmonary functional tests. In line, serum AGGF1 levels were significantly correlated with mRSS, serum KL-6 and surfactant protein D levels, RVSP, and %DLCO. These results uncovered notable correlations between serum AGGF1 levels and key cutaneous and vascular involvements in SSc, suggesting potential roles of AGGF1 in SSc pathogenesis.

Diosgenin improves post-myocardial infarction cardiac function via HAND2-induced angiogenesis

While diosgenin has been demonstrated effective in various cardiovascular diseases, its specific impact on treating heart attacks remains unclear. Our research revealed that diosgenin significantly improved cardiac function in a myocardial infarction (MI) mouse model, reducing cardiac fibrosis and cell apoptosis while promoting angiogenesis. Mechanistically, diosgenin upregulated the Hand2 expression, promoting the proliferation and migration of endothelial cells under hypoxic conditions. Acting as a transcription factor, HAND2 activated the angiogenesis-related gene Aggf1. Conversely, silencing Hand2 inhibited the diosgenin-induced migration of hypoxic endothelial cells and angiogenesis. In summary, these findings provide new insights into the protective role of diosgenin in MI, validating its effect on angiogenic activity and providing a theoretical basis for clinical treatment strategies.

Exploring early DNA methylation alterations in type 1 diabetes: implications of glycemic control

Background

Prolonged hyperglycemia causes diabetes-related micro- and macrovascular complications, which combined represent a significant burden for individuals living with diabetes. The growing scope of evidence indicates that hyperglycemia affects the development of vascular complications through DNA methylation.

Methods

A genome-wide differential DNA methylation analysis was performed on pooled peripheral blood DNA samples from individuals with type 1 diabetes (T1D) with direct DNA sequencing. Strict selection criteria were used to ensure two age- and sex-matched groups with no clinical signs of chronic complications according to persistent mean glycated hemoglobin (HbA1c) values over 5 years: HbA1c<7% (N=10) and HbA1c>8% (N=10).

Results

Between the two groups, 8385 differentially methylated CpG sites, annotated to 1802 genes, were identified. Genes annotated to hypomethylated CpG sites were enriched in 48 signaling pathways. Further analysis of key CpG sites revealed four specific regions, two of which were hypermethylated and two hypomethylated, associated with long non-coding RNA and processed pseudogenes.

Conclusions

Prolonged hyperglycemia in individuals with T1D, who have no clinical manifestation of diabetes-related complications, is associated with multiple differentially methylated CpG sites in crucial genes and pathways known to be linked to chronic complications in T1D.

Translational Relevance of Advanced Age and Atherosclerosis in Preclinical Trials of Biotherapies for Peripheral Artery Disease

Approximately 6% of adults worldwide suffer from peripheral artery disease (PAD), primarily caused by atherosclerosis of lower limb arteries. Despite optimal medical care and revascularization, many PAD patients remain symptomatic and progress to critical limb ischemia (CLI) and risk major amputation. Delivery of pro-angiogenic factors as proteins or DNA, stem, or progenitor cells confers vascular regeneration and functional recovery in animal models of CLI, but the effects are not well replicated in patients and no pro-angiogenic biopharmacological procedures are approved in the US, EU, or China. The reasons are unclear, but animal models that do not represent clinical PAD/CLI are implicated. Consequently, it is unclear whether the obstacles to clinical success lie in the toxic biochemical milieu of human CLI, or in procedures that were optimized on inappropriate models. The question is significant because the former case requires abandonment of current strategies, while the latter encourages continued optimization. These issues are discussed in the context of relevant preclinical and clinical data, and it is concluded that preclinical mouse models that include age and atherosclerosis as the only comorbidities that are consistently present and active in clinical trial patients are necessary to predict clinical success. Of the reviewed materials, no biopharmacological procedure that failed in clinical trials had been tested in animal models that included advanced age and atherosclerosis relevant to PAD/CLI.

Aggf1 Specifies Hemangioblasts at the Top of Regulatory Hierarchy via Npas4l and mTOR-S6K-Emp2-ERK Signaling

BACKGROUND

Hemangioblasts are mesoderm-derived multipotent stem cells for differentiation of all hematopoietic and endothelial cells in the circulation system. However, the underlying molecular mechanism is poorly understood.

METHODS

CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (type II CRISPR RNA-guided endonuclease) editing was used to develop aggf1-/- and emp2-/- knockout zebra fish. Whole-mount in situ hybridization and transgenic Tg(gata1-EGFP [enhanced green fluorescent protein]), Tg(mpx-EGFP), Tg(rag2-DsRed [discosoma sp. red fluorescent protein]), Tg(cd41-EGFP), Tg(kdrl-EGFP), and Tg(aggf1-/-;kdrl-EGFP) zebra fish were used to examine specification of hemangioblasts and hematopoietic stem and progenitor cells (HSPCs), hematopoiesis, and vascular development. Quantitative real-time polymerase chain reaction and Western blot analyses were used for expression analysis of genes and proteins.

RESULTS

Knockout of aggf1 impaired specification of hemangioblasts and HSPCs, hematopoiesis, and vascular development in zebra fish. Expression of npas4l/cloche-the presumed earliest marker for hemangioblast specification-was significantly reduced in aggf1-/- embryos and increased by overexpression of aggf1 in embryos. Overexpression of npas4l rescued the impaired specification of hemangioblasts and HSPCs and development of hematopoiesis and intersegmental vessels in aggf1-/- embryos, placing aggf1 upstream of npas4l in hemangioblast specification. To identify the underlying molecular mechanism, we identified emp2 as a key aggf1 downstream gene. Similar to aggf1, emp2 knockout impaired the specification of hemangioblasts and HSPCs, hematopoiesis, and angiogenesis by increasing the phosphorylation of ERK1/2 (extracellular signal-regulated protein kinase 1/2). Mechanistic studies showed that aggf1 knockdown and knockout significantly decreased the phosphorylated levels of mTOR (mammalian target of rapamycin) and p70 S6K (ribosomal protein S6 kinase), resulting in reduced protein synthesis of Emp2 (epithelial membrane protein 2), whereas mTOR activator MHY1485 (4,6-dimorpholino-N-(4-nitrophenyl)-1,3,5-triazin-2-amine) rescued the impaired specification of hemangioblasts and HSPCs and development of hematopoiesis and intersegmental vessels and reduced Emp2 expression induced by aggf1 knockdown.

CONCLUSIONS

These results indicate that aggf1 acts at the top of npas4l and becomes the earliest marker during specification of hemangioblasts. Our data identify a novel signaling axis of Aggf1 (angiogenic factor with G-patch and FHA domain 1)-mTOR-S6K-ERK1/2 for specification of hemangioblasts and HSPCs, primitive and definitive hematopoiesis, and vascular development. Our findings provide important insights into specification of hemangioblasts and HSPCs essential for the development of the circulation system.

AGGF1 therapy inhibits thoracic aortic aneurysms by enhancing integrin α7-mediated inhibition of TGF-β1 maturation and ERK1/2 signaling

Thoracic aortic aneurysm (TAA) is a localized or diffuse dilatation of the thoracic aortas, and causes many sudden deaths each year worldwide. However, there is no effective pharmacologic therapy. Here, we show that AGGF1 effectively blocks TAA-associated arterial inflammation and remodeling in three different mouse models (mice with transverse aortic constriction, Fbn1^C1041G/+ mice, and β-aminopropionitrile-treated mice). AGGF1 expression is reduced in the ascending aortas from the three models and human TAA patients. Aggf1^+/- mice and vascular smooth muscle cell (VSMC)-specific Aggf1^smcKO knockout mice show aggravated TAA phenotypes. Mechanistically, AGGF1 enhances the interaction between its receptor integrin α7 and latency-associated peptide (LAP)-TGF-β1, blocks the cleavage of LAP-TGF-β1 to form mature TGF-β1, and inhibits Smad2/3 and ERK1/2 phosphorylation in VSMCs. Pirfenidone, a treatment agent for idiopathic pulmonary fibrosis, inhibits TAA-associated vascular inflammation and remodeling in wild type mice, but not in Aggf1^+/- mice. In conclusion, we identify an innovative AGGF1 protein therapeutic strategy to block TAA-associated vascular inflammation and remodeling, and show that efficacy of TGF-β inhibition therapies require AGGF1.

Engineering bioactive nanoparticles to rejuvenate vascular progenitor cells

Fetal exposure to gestational diabetes mellitus (GDM) predisposes children to future health complications including type-2 diabetes mellitus, hypertension, and cardiovascular disease. A key mechanism by which these complications occur is through stress-induced dysfunction of endothelial progenitor cells (EPCs), including endothelial colony-forming cells (ECFCs). Although several approaches have been previously explored to restore endothelial function, their widespread adoption remains tampered by systemic side effects of adjuvant drugs and unintended immune response of gene therapies. Here, we report a strategy to rejuvenate circulating vascular progenitor cells by conjugation of drug-loaded liposomal nanoparticles directly to the surface of GDM-exposed ECFCs (GDM-ECFCs). Bioactive nanoparticles can be robustly conjugated to the surface of ECFCs without altering cell viability and key progenitor phenotypes. Moreover, controlled delivery of therapeutic drugs to GDM-ECFCs is able to normalize transgelin (TAGLN) expression and improve cell migration, which is a critical key step in establishing functional vascular networks. More importantly, sustained pseudo-autocrine stimulation with bioactive nanoparticles is able to improve in vitro and in vivo vasculogenesis of GDM-ECFCs. Collectively, these findings highlight a simple, yet promising strategy to rejuvenate GDM-ECFCs and improve their therapeutic potential. Promising results from this study warrant future investigations on the prospect of the proposed strategy to improve dysfunctional vascular progenitor cells in the context of other chronic diseases, which has broad implications for addressing various cardiovascular complications, as well as advancing tissue repair and regenerative medicine.

Drug-loaded liposomal nanoparticles conjugated to endothelial colony-forming cells can improve the vasculogenic potential of vascular progenitor cells exposed to gestational diabetes mellitus.

Therapeutic angiogenesis-based strategy for peripheral artery disease

Peripheral artery disease (PAD) poses a great challenge to society, with a growing prevalence in the upcoming years. Patients in the severe stages of PAD are prone to amputation and death, leading to poor quality of life and a great socioeconomic burden. Furthermore, PAD is one of the major complications of diabetic patients, who have higher risk to develop critical limb ischemia, the most severe manifestation of PAD, and thus have a poor prognosis. Hence, there is an urgent need to develop an effective therapeutic strategy to treat this disease. Therapeutic angiogenesis has raised concerns for more than two decades as a potential strategy for treating PAD, especially in patients without option for surgery-based therapies. Since the discovery of gene-based therapy for therapeutic angiogenesis, several approaches have been developed, including cell-, protein-, and small molecule drug-based therapeutic strategies, some of which have progressed into the clinical trial phase. Despite its promising potential, efforts are still needed to improve the efficacy of this strategy, reduce its cost, and promote its worldwide application. In this review, we highlight the current progress of therapeutic angiogenesis and the issues that need to be overcome prior to its clinical application.

Identification and characterization of a special type of subnuclear structure: AGGF1-coated paraspeckles

AGGF1 is an angiogenic factor with G-Patch and FHA domains 1 described by our group. Gain-of-function mutations in AGGF1 cause Klippel-Trenaunay syndrome, whereas somatic loss-of-function mutations cause cancer. Paraspeckles are small membraneless subnuclear structures with a diameter of 0.5-1 μm, and composed of lncRNA NEAT1 as the scaffold and three core RNA-binding proteins NONO, PSPC1, and PSF. Here, we show that AGGF1 is a key regulatory and structural component of paraspeckles that induces paraspeckle formation, forms an outside rim of paraspeckles, wraps around the NONO/PSF/PSPC1/NEAT1 core, and regulates the size and number of paraspeckles. AGGF1-paraspeckles are larger (>1 μm) than conventional paraspeckles. RNA-FISH in combination with immunostaining shows that AGGF1, NONO, and NEAT1_2 co-localize in 20.58% of NEAT1_2-positive paraspeckles. Mechanistically, AGGF1 interacts with NONO, PSF, and HNRNPK, and upregulates NEAT1_2, a longer, 23 kb NEAT1 transcript with a key role in regulation of paraspeckle size and number. RNA-immunoprecipitation shows that AGGF1 interacts with NEAT1, which may be another possible mechanism underlying the formation of AGGF1-paraspeckles. NEAT1_2 knockdown reduces the number and size of AGGF1-paraspeckles. Functionally, AGGF1 regulates alternative RNA splicing as it decreases the exon skipping/inclusion ratio in a CD44 model. AGGF1 is also localized in some nuclear foci without NEAT1 or NONO, suggesting that AGGF1 is an important liquid-liquid phase separation (LLPS) driver for other types of AGGF1-positive nuclear condensates (referred to as AGGF1-bodies). Our results identify a special type of AGGF1-coated paraspeckles and provide important insights into the formation, structure, and function of paraspeckles.

Neuroprotective effect of AGGF1 against isoflurane-induced cognitive dysfunction in aged rats through activating the PI3K/AKT signaling pathways

PURPOSE

This study aimed to evaluate and identify the value and explore the mechanisms of Angiogenic Factor with G-patch and FHA domains 1 (AGGF1) in postoperative cognitive dysfunction (POCD).

METHODS

Rats were separated into four different groups, namely sham, isoflurane, isoflurane + recombinant human Aggf1 (rh-Aggf1) (5 μg kg-1), and isoflurane + rh-Aggf1 (10 μg kg-1). qPCR and western blot assays were applied to detect the correlation between the expression of AGGF1 and isoflurane administration. Then, the Morris water maze (MWM) test was applied to evaluate the effect of AGGF1 on improving the POCD rats. Subsequently, TUNEL assay was applied and the cell apoptosis-related proteins were tested to reveal the anti-apoptotic effect of AGGF1 in POCD rats. Furthermore, the mRNA and protein levels of TNF-α, IL-6, and IL-1β were also detected by qPCR and ELISA to verify the anti-inflammatory effects of AGGF1 on POCD rats. Besides, the protein expression levels of PI3K, Akt, and NF-κB in each group were examined by western blot.

RESULTS

In this study, the results revealed that isoflurane induced a decrease in AGGF1 expression in the hippocampus of aged rats. In addition, exogenous AGGF1 attenuated POCD in aged rats. Meanwhile, exogenous AGGF1 had anti-apoptotic and anti-inflammatory effects in POCD rats. Further research indicated that AGGF1 activated the PI3K/Akt pathway.

CONCLUSION

AGGF1 has neuroprotective effect against isoflurane-induced cognitive dysfunction in aged rats via activating the PI3K/AKT signaling pathways.

Regulation of endothelial progenitor cell functions during hyperglycemia: new therapeutic targets in diabetic wound healing

Diabetes is primarily characterized by hyperglycemia, and its high incidence is often very costly to patients, their families, and national economies. Unsurprisingly, the number and function of endothelial progenitor cells (EPCs) decrease in patients resulting in diabetic wound non-healing. As precursors of endothelial cells (ECs), these cells were discovered in 1997 and found to play an essential role in wound healing. Their function, number, and role in wound healing has been widely investigated. Hitherto, a lot of complex molecular mechanisms have been discovered. In this review, we summarize the mechanisms of how hyperglycemia affects the function and number of EPCs and how the affected cells impact wound healing. We aim to provide a complete summary of the relationship between diabetic hyperglycosemia, EPCs, and wound healing, as well as a better comprehensive platform for subsequent related research.

Endothelial cell metabolic memory causes cardiovascular dysfunction in diabetes

AIMS

The aim of this study was to identify the molecular mechanism for hyperglycaemia-induced metabolic memory in endothelial cells (ECs), and to show its critical importance to development of cardiovascular dysfunction in diabetes.

METHODS AND RESULTS

Hyperglycaemia induces increased nuclear factor-κB (NF-κB) signalling, up-regulation of miR-27a-3p, down-regulation of nuclear factor erythroid-2 related factor 2 (NRF2) expression, increased transforming growth factor-β (TGF-β) signalling, down-regulation of miR-29, and induction of endothelial-to-mesenchymal transition (EndMT), all of which are memorized by ECs and not erased when switched to a low glucose condition, thereby causing perivascular fibrosis and cardiac dysfunction. Similar metabolic memory effects are found for production of nitric oxide (NO), generation of reactive oxygen species (ROS), and the mitochondrial oxygen consumption rate in two different types of ECs. The observed metabolic memory effects in ECs are blocked by NRF2 activator tert-butylhydroquinone and a miR-27a-3p inhibitor. In vivo, the NRF2 activator and miR-27a-3p inhibitor block cardiac perivascular fibrosis and restore cardiovascular function by decreasing NF-κB signalling, down-regulating miR-27a-3p, up-regulating NRF2 expression, reducing TGF-β signalling, and inhibiting EndMT during insulin treatment of diabetes in streptozotocin-induced diabetic mice, whereas insulin alone does not improve cardiac function.

CONCLUSIONS

Our data indicate that disruption of hyperglycaemia-induced EC metabolic memory is required for restoring cardiac function during treatment of diabetes, and identify a novel molecular signalling pathway of NF-κB/miR-27a-3p/NRF2/ROS/TGF-β/EndMT involved in metabolic memory.

Receptor and Molecular Mechanism of AGGF1 Signaling in Endothelial Cell Functions and Angiogenesis

Objective

Angiogenic factor AGGF1 (angiogenic factor with G-patch and FHA [Forkhead-associated] domain 1) promotes angiogenesis as potently as VEGFA (vascular endothelial growth factor A) and regulates endothelial cell (EC) proliferation, migration, specification of multipotent hemangioblasts and venous ECs, hematopoiesis, and vascular development and causes vascular disease Klippel-Trenaunay syndrome when mutated. However, the receptor for AGGF1 and the underlying molecular mechanisms remain to be defined.

Approach and Results

Using functional blocking studies with neutralizing antibodies, we identified [alpha]5[beta]1 as the receptor for AGGF1 on ECs. AGGF1 interacts with [alpha]5[beta]1 and activates FAK (focal adhesion kinase), Src (proto-oncogene tyrosine-protein kinase), and AKT (protein kinase B). Functional analysis of 12 serial N-terminal deletions and 13 C-terminal deletions by every 50 amino acids mapped the angiogenic domain of AGGF1 to a domain between amino acids 604-613 (FQRDDAPAS). The angiogenic domain is required for EC adhesion and migration, capillary tube formation, and AKT activation. The deletion of the angiogenic domain eliminated the effects of AGGF1 on therapeutic angiogenesis and increased blood flow in a mouse model for peripheral artery disease. A 40-mer or 15-mer peptide containing the angiogenic domain blocks AGGF1 function, however, a 15-mer peptide containing a single amino acid mutation from -RDD- to -RGD- (a classical RGD integrin-binding motif) failed to block AGGF1 function.

Conclusions

We have identified integrin [alpha]5[beta]1 as an EC receptor for AGGF1 and a novel AGGF1-mediated signaling pathway of [alpha]5[beta]1-FAK-Src-AKT for angiogenesis. Our results identify an FQRDDAPAS angiogenic domain of AGGF1 crucial for its interaction with [alpha]5[beta]1 and signaling.

The Relationship Between UBE2C and AGGF1 Overexpression and Tumor Angiogenesis in Non-Small Cell Lung Cancer

Background

Tumor infiltration and metastasis are the leading causes of death for patients with tumors. Angiogenesis is a prerequisite for tumor growth and metastasis. Angiogenic factor with G patch and FHA domains 1 (AGGF1) is an angiogenic factor, whereas ubiquitin-conjugating enzyme E2C (UBE2C) functions in protein ubiquitination. Microvessel density (MVD) is the most common indicator of tumor microvessels, and vasculogenic mimicry (VM) facilitates blood supply to tumors. This study explored UBE2C and AGGF1 expression in non-small cell lung cancer (NSCLC) and their relationship with angiogenesis and prognosis to identify biological factors that might predict NSCLC infiltration, metastasis, and prognosis.

Methods

The specimens and clinical pathological data of patients with NSCLC confirmed by pathology after surgical resection between January 2013 and December 2015 were collected. UBE2C and AGGF1 expression, as well as microvessel formation and VM in NSCLC, was observed using immunohistochemistry. The relationships between UBE2C, AGGF1, MVD, VM, and clinical pathological parameters and their relationships with overall survival (OS) and disease-free survival (DFS) were analyzed.

Results

UBE2C and AGGF1 levels in NSCLC tissues were significantly higher than those in corresponding normal tissues (57.1% vs 15.6 and 59.7% vs 25.3%, respectively; P < 0.05). UBE2C, AGGF1, MVD, and VM were positively correlated with each other (P < 0.05) and were all related to tumor size, lymph node metastasis, and tumor-node-metastasis stage (P < 0.05). Kaplan–Meier analysis showed that patient OS and DFS in the UBE2C, AGGF1, VM-positive, and high-MVD groups were reduced (all P < 0.001). Univariate and multivariate analyses showed that UBE2C, AGGF1, VM, and MVD were independent risk factors for NSCLC prognosis.

Conclusion

UBE2C and AGGF1 overexpression is associated with angiogenesis and poor prognosis and may be important for predicting NSCLC invasion, metastasis, and prognosis.

Fuyuan Xingnao Decoction Promotes Angiogenesis Through the Rab1/AT1R Pathway in Diabetes Mellitus Complicated With Cerebral Infarction

Fuyuan Xingnao decoction (FYXN), a traditional Chinese formula comprised of seven herbs, has been utilized to treat diabetes mellitus complicated with cerebral infarction (DMCI) for years. Yet, its protective and regulatory mechanism is poorly understood. The aim of the study is to investigate the effects of FYXN on DMCI in vitro and in vivo, as well as its mechanism in angiogenesis. For in vivo experiments, FYXN was administered to DMCI rats with streptozotocin (STZ) injection-induced diabetes. Then middle cerebral artery occlusion (MCAO) was conducted and the cerebral cortex sections of the rats were obtained. The ultrastructure of cerebral microvessels and new vessel density of ischemic penumbra were evaluated by the transmission electron microscopy (TEM) assay and immunohistochemistry, respectively. Protein and mRNA expression levels of Rab1/AT1R in cortex were assayed by Western blotting and real-time fluorescence quantitative real-time polymerase chain reaction (RT-qPCR). In vitro, FYXN serum was produced in rats on the fourth day 2 h after the last FYXN administration. Green fluorescence was observed after transfection with lentivirus packaged Rab1-WT or siRNA for 24 h. The activity of brain microvascular endothelial cells (BMECs) treated with sera from these rats was tested by MTT assay and Transwell assays, respectively. The expression of AT1R on the cell membrane and endoplasmic reticulum of BMECs was evaluated by immunofluorescence staining. Protein expression levels of signaling molecules in the Rab1/AT1R pathways were also detected. Results showed that in vivo, FYXN treatment significantly intensified CD31 staining in the cortical areas and enhanced the mRNA and protein levels of AT1R, Ang II, Rab1a, Rab1b and VEGF expression in ischemic cerebral cortex tissues. In vitro, the expression levels of AT1R, Ang II, Rab1a, Rab1b and VEGF in the cerebral infarction model group were significantly higher than those in the control group, with further increases after administration of FYXN drug serum. FYXN promoted the proliferation and migration of BMECs by activating the Rab1/AT1R signaling pathway. In conclusion, FYXN exerts a protective effect against DMCI by promoting angiogenesis via the Rab1/AT1R pathway, which provides strong evidence for the therapeutic effect of FYXN on DMCI.

Experimental Study on the Effect of Allogeneic Endothelial Progenitor Cells on Wound Healing in Diabetic Mice

Endothelial progenitor cells (EPCs) are involved in the neovascularization in traumatic and ischemic sites, but EPCs are "detained" in bone marrow under diabetic conditions, which results in reduction of the number of EPCs and their biological activity in peripheral blood. Based on our previous study to mobilize autologous bone marrow EPCs by administering AMD3100+G-CSF to realize the optimal effect, our present study is aimed at exploring the effects of transplanting EPCs locally in a wound model of diabetic mice. First, we prepared and identified EPCs, and the biological functions and molecular characteristics were compared between EPCs from DB/+ and DB/DB mice. Then, we performed full-thickness skin resection in DB/DB mice and tested the effect of local transplantation of EPCs on skin wound healing. The wound healing process was recorded using digital photographs. The animals were sacrificed on postoperative days 7, 14, and 17 for histological and molecular analysis. Our results showed that DB/+ EPCs were biologically more active than those of DB/DB EPCs. When compared with the control group, local transplantation of EPCs accelerated wound healing in DB/DB mice by promoting wound granulation tissue formation, angiogenesis, and collagen fiber deposition, but there was no significant difference in wound healing between DB/+ EPCs and DB/DB EPCs transplanted into the wound. Furthermore, local transplantation of EPCs promoted the expression of SDF-1, CXCR4, and VEGF. We speculated that EPC transplantation may promote wound healing through the SDF-1/CXCR4 axis. This point is worth exploring further. Present data are of considerable significance because they raise the possibility of promoting wound healing by isolating autologous EPCs from the patient, which provides a new approach for the clinical treatment of diabetic wounds in the future.

Exendin-4 reverses high glucose-induced endothelial progenitor cell dysfunction via SDF-1β/CXCR7-AMPK/p38-MAPK/IL-6 axis

AIM

Exendin-4, a glucagon-like peptide-1 (GLP-1) analog, has been used for treating diabetes mellitus (DM). However, its effects on improving the dysfunction of high glucose (HG)-induced endothelial progenitor cells (EPCs) remain unclear. The present study explored the effects of Exendin-4 on improving dysfunction of EPCs and the underlying mechanism.

METHODS

EPCs were isolated from SD rats and identified by flow cytometry. Next, the EPCs were treated by HG and high or low concentration of Exendin-4, and cell viability, migration and tube formation were, respectively, examined by performing MTT assay, wound-healing assay and tube formation assay. Interleukin-6 (IL-6) secretion was measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions of relative stromal-derived growth factor-1β (SDF-1β), C-X-C chemokine receptor type 7 (CXCR7), AMP-activated protein kinase (AMPK), p38 and expressions of CXCR7 and IL-6 in EPCs were measured by Western blot. The cell behaviors of EPCs treated by HG and Exendin-4 with or without silencing of CXCR7 and IL-6 were detected.

RESULTS

Exendin-4 reversed the inhibitory effects of HG on viability, migration and tube formation of EPCs and on SDF-1β/CXCR7-AMPK pathway in EPCs in a dose-dependent manner. Moreover, Exendin-4 promoted the effects of HG on IL-6 level in EPCs through the promotion of p38-MAPK phosphorylation and reduction of cleaved caspase-3 protein expressions in EPCs. However, silencing of CXCR7 and IL-6 reversed the effects of Exendin-4 on cell behaviors, inactivated SDF-1β/CXCR7-AMPK pathway and increased cleaved caspase-3 expression in EPCs.

CONCLUSIONS

Exendin-4 could ameliorate HG-induced EPC dysfunction through regulating the production of IL-6 via SDF-1β/CXCR7-AMPK/p38-MAPK axis.

Identification and Comparison of Hyperglycemia-Induced Extracellular Vesicle Transcriptome in Different Mouse Stem Cells

Extracellular vesicles (EVs) derived from stem /progenitor cells harbor immense potential to promote cardiomyocyte survival and neovascularization, and to mitigate ischemic injury. However, EVs’ parental stem/progenitor cells showed modest benefits in clinical trials, suggesting autologous stem cell/EV quality might have been altered by stimuli associated with the co-morbidities such as hyperglycemia associated with diabetes. Hyperglycemia is a characteristic of diabetes and a major driving factor in cardiovascular disease. The functional role of stem/progenitor cell-derived EVs and the molecular signature of their secreted EV cargo under hyperglycemic conditions remain elusive. Therefore, we hypothesized that hyperglycemic stress causes transcriptome changes in stem/progenitor cell-derived EVs that may compromise their reparative function. In this study, we performed an unbiased analysis of EV transcriptome signatures from 3 different stem/progenitor cell types by RNA sequencing. The analysis revealed differential expression of a variety of RNA species in EVs. Specifically, we identified 241 common-dysregulated mRNAs, 21 ncRNAs, and 16 miRNAs in three stem cell-derived EVs. Gene Ontology revealed that potential function of common mRNAs mostly involved in metabolism and transcriptional regulation. This study provides potential candidates for preventing the adverse effects of hyperglycemia-induced stem/progenitor cell-derived EV dysfunction, and reference data for future biological studies and application of stem/progenitor cell-derived EVs.

Vaccarin Regulates Diabetic Chronic Wound Healing through FOXP2/AGGF1 Pathways

Background: Diabetes mellitus is a growing global health issue nearly across the world. Diabetic patients who are prone to develop diabetes-related complications often exhibit progressive neuropathy (painless and sensory loss). It is usual for small wounds to progress to ulceration, which especially worsens with peripheral arterial disease and in the presence of anaerobic bacteria, culminating into gangrene. In our study, vaccarin (VAC), the main active monomer extracted from Chinese herb vaccariae semen, is proven to have a role in promoting diabetic chronic wound healing through a cytoprotective role under high glucose conditions. Materials and methods: We constructed a pressure ulcer on both VAC-treated and control mice based on a type 1 diabetes (T1DM) model. The wound healing index was evaluated by an experimental wound assessment tool (EWAT). We also determined the effect of VAC on the proliferation and cell migration of human microvascular endothelial cells (HMEC-1) by a cell counting kit (CCK-8), a scratch and transwell assay. Results: The results demonstrated that VAC could promote the proliferation and migration of high glucose-stimulated HMEC-1 cells, which depend on the activation of FOXP2/AGGF1. Activation of the angiogenic factor with G patch and FHA domains 1 (AGGF1) caused enhanced phosphorylation of serine/threonine kinase (Akt) and extracellular regulated protein kinases (Erk1/2). By silencing the expression of forkhead box p2 (FOXP2) protein by siRNA, both mRNA and protein expression of AGGF1 were downregulated, leading to a decreased proliferation and migration of HMEC-1 cells. In addition, a diabetic chronic wound model in vivo unveiled that VAC had a positive effect on chronic wound healing, which involved the activation of the above-mentioned pathways. Conclusions: In summary, our study found that VAC promoted chronic wound healing in T1DM mice by activating the FOXP2/AGGF1 pathway, indicating that VAC may be a promising candidate for the treatment of the chronic wounds of diabetic patients.