What Went Wrong with VEGF-A in Peripheral Arterial Disease? A Systematic Review and Biological Insights on Future Therapeutics

Caesalpinia sappan L. ethyl acetate extract regulated angiogenesis in atherosclerosis by modulating the miR-126/VEGF signalling pathway

Aims of the study

To investigate the regulatory mechanism of Caesalpinia sappan L. ethyl acetate extract (CSEAE) on angiogenesis in atherosclerosis (AS) based on the miR-126/VEGF signalling pathway.

Materials and methods

Our study first screened for differentially expressed microRNAs (miRNAs) associated with AS using the Gene Expression Omnibus (GEO) public database at the National Center for Biotechnology Information (NCBI) and R language software. Subsequently, our study verified the target-regulatory relationship between miR-126 and vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs) by using the "TargetScan" website and dual-luciferase reporter assay. In cellular experiments, Our study used cell proliferation assays and flow cytometry to assess the effects of CSEAE-Mediated serum on the proliferation and apoptosis of HUVECs. In animal experiments, our study used HE staining, Oil Red O staining and immunohistochemistry (IHC) staining to detect plaque area/lumen area (%), lipid area/plaque area (%) and microvessel density (MVD) in mouse aortas. In addition, our study performed RT‒PCR, ELISA and Western blot assays in ex vivo and in vivo experiments.

Results

A total of 39 differentially expressed miRNAs of AS were identified, among which the miR-126 expression level was significantly downregulated. Dual luciferase reporter gene assay results showed that miR-126 and VEGF have a targeting relationship, and the miR-126 mimic could inhibit the luciferase activity of the wild-type VEGF reporter gene vector (p value < 0.01). In cellular experiments, cell proliferation assays and flow cytometry results showed that CSEAE-Mediated serum significantly increased the proliferative activity after 24-72 h of treatment (p-value <0.01) and decreased the apoptotic level of HUVECs (p value < 0.01), and RT‒PCR results showed that CSEAE-Mediated serum significantly upregulated the expression of miR-126 (p value < 0.01) and downregulated the expression of VEGF mRNA in HUVECs (p value < 0.01). In vivo experiments, HE staining and IHC staining showed that CSEAE significantly reduced the MVD in the aorta and plaques of mice (p value < 0.01) and significantly reduced the aortic plaque area/lumen area (%) (p value < 0.01). Moreover, RT‒PCR assay and Western blot analysis results showed that CSEAE significantly upregulated the expression of miR-126 (p value < 0.01), downregulated the expression of VEGF mRNA (p value < 0.01), and decreased the protein expression levels of VEGF (p value < 0.01), phosphatidyl-inositol-3-kinase (PI3K) (p value < 0.01), and Ser/Thr-protein kinase (AKT1) (p value < 0.01) in mouse aortas, while ELISA showed that CSEAE significantly reduced the serum levels of vascular endothelial growth factor receptor (VEGFR2) (p value < 0.01) and hypoxia-inducible factor-1 (HIF-1) (p value < 0.01) in mice.

Conclusion

This study emphasises CSEAE as a natural medicinal extract for the treatment of AS that can improve the migratory viability and reduce the apoptosis of HUVECs to maintain the health of the arterial endothelial microenvironment, while CSEAE also inhibits angiogenesis and delays plaque formation in ApoE-/- mice, suggesting that the therapeutic effect of CSEAE for AS may be related to its inhibition of neovascularisation and that its molecular mechanism may be related to the miR-126/VEGF signalling pathway.

HIF-1α and VEGF Immunophenotypes as Potential Biomarkers in the Prognosis and Evaluation of Treatment Efficacy of Atherosclerosis: A Systematic Review of the Literature

BACKGROUND

Hypoxia-inducible factor 1 alpha (HIF-1α) and its related vascular endothelial growth factor (VEGF) may play a significant role in atherosclerosis and their targeting is a strategic approach that may affect multiple pathways influencing disease progression. This study aimed to perform a systematic review to reveal current evidence on the role of HIF-1α and VEGF immunophenotypes with other prognostic markers as potential biomarkers of atherosclerosis prognosis and treatment efficacy.

METHODS

We performed a systematic review of the current literature to explore the role of HIF-1α and VEGF protein expression along with the relation to the prognosis and therapeutic strategies of atherosclerosis. We used the terms {"Atherosclerosis" [OR] "Atheroma" [OR] "atheromatous plaque" [OR] "plaque atherosclerotic"} [AND] {"HIF-1α"} [AND] {"VEGF"} from 2009 up to May 2024 and the Medline/Embase/PubMed database. We used methodological approaches to assess unbiased data [ROBIS (Risk of Bias in Systematic) tool]. We used study eligibility criteria, and data were collected and evaluated from original articles by two independent teams, judged by an independent reviewer, and reported by PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) 2020.

RESULTS

We included 34 original studies investigating 650 human specimens, 21 different cell lines, and 9 animal models. Increased HIF-1α in vascular smooth muscle cells, macrophages, or endothelial cells, under hypoxia, chronic loss of nitric oxide (NO), or reduced micro ribonucleic acid (miRNA)-17 and miR-20, is associated with the upregulation of pro-inflammatory molecules, such as interleukin-1 beta (IL-1β) or tumor necrosis factor-alpha (TNF-α), increased migration inhibitory factor of macrophages, glycolytic flux, lipid accumulation, necroptosis via miR-383, and adverse effects in atherosclerosis and plaque vulnerability. However, increased HIF-1α in lymphocytes is associated with decreased interferon-gamma (IFN-γ) and a favorable prognosis. Increased VEGF in a coronary artery, activated macrophages, or chronic exposure to methamphetamine is associated with elevated levels of serum inflammatory cells (interleukin-18; IL18), p38 mitogen-activated protein kinase (MAPK) phosphorylation, lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), and signal transducer and activator of transcription 6 isoform B (STAT6B) overexpression, leading to atherosclerosis progression and plaque break. However, VEGF overexpression in serum is marginally associated with an elevated risk for atherosclerosis. In contrast, stable overexpression of VEGF in macrophages correlates with reduced hyperplasia after arterial injury, reduced foam cell formation, and attenuation of atherosclerosis progression. HIF-1α/VEGF immunophenotypes reflect atherosclerosis treatment efficacy using, among others, HIF-inhibitors, statins, polyphenols, miR-497-5p, methylation modification, adenosine receptor antagonists, natural products, or glycosides.

CONCLUSION

We present an overview of HIF-1α/VEGF expression in chronic inflammatory-related atherosclerosis disease. Exploring pathogenetic mechanisms and therapeutic options, we included several studies using variable methods to evaluate HIF-1α/VEGF immunophenotypes with controversial and innovative results. Data limitations may include the use of different survival methods. Our data support HIF-1α/VEGF immunophenotypes as potential biomarkers of atherosclerosis prognosis and treatment efficacy.

Bioengineered human arterial equivalent and its applications from vascular graft to in vitro disease modeling

Arterial disorders such as atherosclerosis, thrombosis, and aneurysm pose significant health risks, necessitating advanced interventions. Despite progress in artificial blood vessels and animal models aimed at understanding pathogenesis and developing therapies, limitations in graft functionality and species discrepancies restrict their clinical and research utility. Addressing these issues, bioengineered arterial equivalents (AEs) with enhanced vascular functions have been developed, incorporating innovative technologies that improve clinical outcomes and enhance disease progression modeling. This review offers a comprehensive overview of recent advancements in bioengineered AEs, systematically summarizing the bioengineered technologies used to construct these AEs, and discussing their implications for clinical application and pathogenesis understanding. Highlighting current breakthroughs and future perspectives, this review aims to inform and inspire ongoing research in the field, potentially transforming vascular medicine and offering new avenues for preclinical and clinical advances.

PEGylation of Human Vascular Endothelial Growth Factor

Vascular endothelial growth factor A-165 (VEGF-A165) positively modulates neointimal hyperplasia, lumen stenosis, and neovascularization. One challenge for the use of VEGF-A165 for potential therapy is its short serum half-life. Therefore, we are designing VEGF-A165 bioconjugates carrying polyethylene glycol (PEG). The purity of the recombinantly expressed human VEGF-A165 exceeded 90%. The growth factor had a half-maximal effective concentration of 0.9 ng/mL (EC50) and induced tube formation of human umbilical vein endothelial cells. PEGylation was conducted by Schiff base reaction followed by reductive amination. After purification, two species were obtained, with one or two PEG attached per VEGF-A165 dimer. Both resulting bioconjugates had a purity exceeding 90%, wild-type bioactivity, and increased hydrodynamic radii as required for prolonging the half-life.

Coactivation of Tie2 and Wnt signaling using an antibody-R-spondin fusion potentiates therapeutic angiogenesis and vessel stabilization in hindlimb ischemia

Therapeutic angiogenesis by intentional formation of blood vessels is essential for treating various ischemic diseases, including limb ischemia. Because Wnt/β-catenin and angiopoietin-1/Tie2 signaling play important roles in endothelial survival and vascular stability, coactivation of these signaling pathways can potentially achieve therapeutic angiogenesis. In this study, we developed a bifunctional antibody fusion, consisting of a Tie2-agonistic antibody and the Furin domains of R-spondin 3 (RSPO3), to simultaneously activate Tie2 and Wnt/β-catenin signaling. We identified a Tie2-agonistic antibody T11 that cross-reacted with the extracellular domain of human and mouse Tie2, and evaluated its ability to increase endothelial cell survival and tube formation. We generated a bifunctional T11-RF12 by fusing T11 with the Furin-1 and -2 domains of RSPO3. T11-RF12 could bind not only to Tie2, but also to LGR5 and ZNRF3, which are counterparts of the Furin-1 and -2 domains. T11-RF12 significantly increased Wnt/β-catenin signaling, as well as the formation of capillary-like endothelial tubes, regardless of the presence of Wnt ligands. Coactivation of Tie2 and Wnt/β-catenin signaling by T11-RF12 increased the blood flow, and thereby reduced foot necrosis in a mouse hindlimb ischemia model. In particular, T11-RF12 induced therapeutic angiogenesis by promoting vessel stabilization through pericyte coverage and retaining endothelial expression of Frizzled 10 and active β-catenin. These results indicate that the agonistic synergism of Tie2 and Wnt/β-catenin signaling achieved using T11-RF12 is a novel therapeutic option with potential for treating limb ischemia and other ischemic diseases.

A review of the current state in neointimal hyperplasia development following endovascular intervention and minor emphasis on new horizons in immunotherapy

Endovascular strategies play a vital role in the treatment of peripheral arterial disease (PAD). However, luminal loss or restenosis after endovascular intervention remains a significant challenge. The main underlying mechanisms are negative vascular remodeling and elastic recoil in balloon angioplasty. During stenting, the main reason for this complex is neointimal proliferation. Endothelial cell injury due to endovascular intervention initiates a series of molecular events, such as overexpression of growth factors, cytokine secretion, and adhesion molecules. These induce platelet activation and inflammatory processes, which trigger the proliferation and migration of vascular smooth muscle cells into the intima, resulting in neointimal hyperplasia. During this process, PAD progression is mainly caused by chronic inflammation, in which macrophages play a central role. Of the current strategies, drug release interventions aim to suppress restenosis using antiproliferative drugs, such as sirolimus and paclitaxel, during drug release. These drugs inhibit vascular reendothelialization and reduce late in-stent restenosis. For this reason, immunotherapy can be considered an important alternative. Interventions that polarize macrophages to the M2 subtype are particularly important, as they shape the immune response in an anti-inflammatory direction and contribute to tissue repair. However, there are several challenges to overcome, such as localizing antiproliferative or polarizing agents only to areas of vascular injury. This review discusses, based on the early study observations, immunotherapeutic approaches to prevent restenosis after endovascular intervention for the treatment of PAD.

The Concentration of Pro- and Antiangiogenic Factors in Saliva and Gingival Crevicular Fluid Compared to Plasma in Patients with Peripheral Artery Disease and Type 2 Diabetes

Several studies have investigated various biomarkers in relation to peripheral artery disease (PAD) for disease stratification and early-onset detection. In PAD, angiogenesis is required for tissue restoration and tissue perfusion. Considering changes in angiogenesis in patients with PAD, angiogenic factors could be explored as one of the new prognostic molecules. In recent studies, saliva and gingival crevicular fluid (GCF) have gained recognition as new, easily obtained diagnostic materials. This study aimed to compare the levels of selected circulating angiogenic factors (VEGF-A, PDGF-BB, and ANG-1) in unstimulated whole saliva (WS) and GCF versus plasma at three points in time to find possible correlations between their concentrations among patients with PAD and diabetes type 2 in 32 patients with Rutherford stages 5 and 6. A significant positive correlation has been demonstrated between circulating PDGF-BB levels in GCF and plasma. In most cases, comorbidities do not have an impact on the change in general correlation for the whole group. Our results clearly showed that GCF could be a good source for PDGF assessment. However, future studies with a larger number of subjects are warranted to confirm this finding and identify the most accurate angiogenic biomarkers in saliva or GCF that could be applied in clinical practice.

Muscle progenitor cells are required for skeletal muscle regeneration and prevention of adipogenesis after limb ischemia

Skeletal muscle injury in peripheral artery disease (PAD) has been attributed to vascular insufficiency, however evidence has demonstrated that muscle cell responses play a role in determining outcomes in limb ischemia. Here, we demonstrate that genetic ablation of Pax7+ muscle progenitor cells (MPCs) in a model of hindlimb ischemia (HLI) inhibited muscle regeneration following ischemic injury, despite a lack of morphological or physiological changes in resting muscle. Compared to control mice (Pax7WT), the ischemic limb of Pax7-deficient mice (Pax7Δ) was unable to generate significant force 7 or 28 days after HLI. A significant increase in adipose was observed in the ischemic limb 28 days after HLI in Pax7Δ mice, which replaced functional muscle. Adipogenesis in Pax7Δ mice corresponded with a significant increase in PDGFRα+ fibro/adipogenic progenitors (FAPs). Inhibition of FAPs with batimastat decreased muscle adipose but increased fibrosis. In vitro, Pax7Δ MPCs failed to form myotubes but displayed increased adipogenesis. Skeletal muscle from patients with critical limb threatening ischemia displayed increased adipose in more ischemic regions of muscle, which corresponded with fewer satellite cells. Collectively, these data demonstrate that Pax7+ MPCs are required for muscle regeneration after ischemia and suggest that muscle regeneration may be an important therapeutic target in PAD.