Divergent endothelial mechanisms drive arteriovenous malformations in Alk1 and SMAD4 loss-of-function

Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder caused by mutations in the bone morphogenetic protein signaling pathway, leading to arteriovenous malformations. While previously thought to share molecular and cellular dysregulation, this study reveals highly distinct mechanisms depending on whether mutations occur in Alk1 or SMAD4. Loss of SMAD4 enhances endothelial cell responses to flow, including flow-regulated transcription and cell migration against blood flow, causing excessive pruning of capillaries and the formation of single large shunts. Conversely, Alk1 deficiency disrupts endothelial flow responses, including cell polarization and directional migration, leading to a dense vascular network and the persistence of a malformation nidus. In vivo cell population tracking of mutant cells validates unique endothelial cell migration defects. Mosaic cell culture models further illustrate that mutant cells co-opt wild-type cells driving distinct Alk1 or SMAD4 mutant-like behavioral defects. These findings demonstrate that arteriovenous malformations develop through fundamentally different cellular mechanisms based on the specific genetic mutation emphasizing the need for tailored diagnostic and therapeutic strategies.

Peptide Lv and Angiogenesis: A Newly Discovered Angiogenic Peptide

Peptide Lv is a small endogenous secretory peptide with ~40 amino acids and is highly conserved among certain several species. While it was first discovered that it augments L-type voltage-gated calcium channels (LTCCs) in neurons, thus it was named peptide "Lv", it can bind to vascular endothelial growth factor receptor 2 (VEGFR2) and has VEGF-like activities, including eliciting vasodilation and promoting angiogenesis. Not only does peptide Lv augment LTCCs in neurons and cardiomyocytes, but it also promotes the expression of intermediate-conductance KCa channels (KCa3.1) in vascular endothelial cells. Peptide Lv is upregulated in the retinas of patients with early proliferative diabetic retinopathy, a disease involving pathological angiogenesis. This review will provide an overview of peptide Lv, its known bioactivities in vitro and in vivo, and its clinical relevance, with a focus on its role in angiogenesis. As there is more about peptide Lv to be explored, this article serves as a foundation for possible future developments of peptide Lv-related therapeutics to treat or prevent diseases.

Identification and Evaluation of Angiogenesis-Related Proteins That Predict Major Adverse Cardiovascular Events in Patients with Peripheral Artery Disease

BACKGROUND

The most common cause of death in patients with peripheral artery disease (PAD) are major adverse cardiovascular events (MACEs), including myocardial infarction (MI) and stroke. However, data on biomarkers that could be used to help predict MACEs in patients with PAD to guide clinical decision making is limited. Angiogenesis-related proteins have been demonstrated to play an important role in systemic atherosclerosis and may act as prognostic biomarkers for MACEs in patients with PAD. In this study, we evaluated a large panel of angiogenesis-related proteins and identified specific biomarkers associated with MACEs in patients with PAD.

METHODS

We conducted a prognostic study using a prospectively recruited cohort of 406 patients (254 with PAD and 152 without PAD). Plasma concentrations of 22 circulating angiogenesis-related proteins were measured at baseline, and the cohort was followed for 2 years. The primary outcome was 2-year MACEs (composite of MI, stroke, or death). Plasma protein concentrations were compared between PAD patients with and without 2-year MACEs using Mann-Whitney U tests. Differentially expressed proteins were further investigated in terms of their prognostic potential. Specifically, Cox proportional hazards analysis was performed to determine the independent association between differentially expressed proteins and 2-year MACEs, controlling for all baseline demographic and clinical characteristics, including existing coronary artery disease and cerebrovascular disease. Kaplan-Meier analysis was conducted to assess 2-year freedom from MACEs in patients with low vs. high levels of the differentially expressed proteins based on median plasma concentrations.

RESULTS

The mean age of the cohort was 68.8 (SD 11.1), and 134 (33%) patients were female. Two-year MACEs occurred in 63 (16%) individuals. The following proteins were significantly elevated in PAD patients with 2-year MACEs compared to those without 2-year MACEs: endostatin (69.15 [SD 58.15] vs. 51.34 [SD 29.07] pg/mL, p < 0.001), angiopoietin-like protein 4 (ANGPTL4) (0.20 [SD 0.09] vs. 0.12 [SD 0.04] pg/mL, p < 0.001), and ANGPTL3 (51.57 [SD 21.92] vs. 45.16 [SD 21.90] pg/mL, p = 0.001). Cox proportional hazards analysis demonstrated that these three proteins were independently associated with 2-year MACEs after adjusting for all baseline demographic and clinical characteristics: endostatin (HR 1.39 [95% CI 1.12-1.71] p < 0.001), ANGPTL4 (HR 1.35 [95% CI 1.08-1.68], p < 0.001), and ANGPTL3 (HR 1.35 [95% CI 1.12-1.63], p < 0.001). Over a 2-year follow-up period, patients with higher levels of endostatin, ANGPTL4, and ANGPTL3 had a lower freedom from MACEs. Supplementary analysis demonstrated that these three proteins were not significantly associated with 2-year MACEs in patients without PAD.

CONCLUSIONS

Among a panel of 22 angiogenesis-related proteins, endostatin, ANGPTL4, and ANGPTL3 were identified to be independently and specifically associated with 2-year MACEs in patients with PAD. Measurement of plasma concentrations of these proteins can support MACE risk stratification in patients with PAD, thereby informing clinical decisions on multidisciplinary referrals to cardiologists, neurologists, and vascular medicine specialists and guiding aggressiveness of medical treatment, thereby improving cardiovascular outcomes in patients with PAD.

Integrin Targeting and Beyond: Enhancing Cancer Treatment with Dual-Targeting RGD (Arginine-Glycine-Aspartate) Strategies

Integrins, an important superfamily of cell adhesion receptors, play an essential role in cancer progression, metastasis, and angiogenesis, establishing them as prime targets for both diagnostic and therapeutic applications. Despite their significant potential, integrin-targeted therapies have faced substantial challenges in clinical trials, including variable efficacy and unmet high expectations. Nevertheless, the consistent expression of integrins on tumor and stromal cells underscores their ongoing relevance and potential. Traditional RGD-based imaging and therapeutic agents have faced limitations, such as inconsistent target expression and rapid systemic clearance, which have reduced their effectiveness. To overcome these challenges, recent research has focused on advancing RGD-based strategies and exploring innovative solutions. This review offers a thorough analysis of the latest developments in the RGD-integrin field, with a particular focus on addressing previous limitations. It delves into new dual-targeting approaches and cutting-edge RGD-based agents designed to improve both tumor diagnosis and therapeutic outcomes. By examining these advancements, this review illuminates new pathways for enhancing the specificity and efficacy of integrin-targeted therapies, paving the way for more effective cancer diagnosis and treatment strategies.

Leptin signaling promotes blood vessel formation in the Xenopus tail during the embryo-larval transition

The signals that regulate peripheral blood vessel formation during development are still under investigation. The hormone leptin promotes blood vessel formation, adipose tissue establishment and expansion, tumor growth, and wound healing, but the underlying mechanisms for these actions are currently unknown. We investigated whether leptin promotes angiogenesis in the developing tail fin using embryonic transgenic xflk-1:GFP Xenopus laevis, which express a green fluorescent protein on vascular endothelial cells to mark blood vessels. We found that leptin protein is expressed in endothelial cells of developing blood vessels and that leptin treatment via injection increased phosphorylated STAT3 signaling, which is indicative of leptin activation of its receptor, in blood vessels of the larval tail fin. Leptin administration via media increased vessel length, branching, and reconnection with the cardinal vein, while decreased leptin signaling via immunoneutralization had an opposing effect on vessel development. We also observed disorganization of major vessels and microvessels of the tail fin and muscle when leptin signaling was decreased. Reduced leptin signaling lowered mRNA expression of cenpk, gpx1, and mmp9, markers for cell proliferation, antioxidation, and extracellular matrix remodeling/cell migration, respectively, in the developing tail, providing insight into three possible mechanisms underlying leptin's promotion of angiogenesis. Together these results illustrate that leptin levels are correlated with embryonic angiogenesis and that leptin coordinates multiple aspects of blood vessel growth and development, showing that leptin is an important morphogen during embryonic development.

Advancements in Understanding the Hide-and-Seek Strategy of Hibernating Breast Cancer Cells and Their Implications in Oncology from a Broader Perspective: A Comprehensive Overview

Despite recent advancements in technology, breast cancer still poses a significant threat, often resulting in fatal consequences. While early detection and treatments have shown some promise, many breast cancer patients continue to struggle with the persistent fear of the disease returning. This fear is valid, as breast cancer cells can lay dormant for years before remerging, evading traditional treatments like a game of hide and seek. The biology of these dormant breast cancer cells presents a crucial yet poorly understood challenge in clinical settings. In this review, we aim to explore the mysterious world of dormant breast cancer cells and their significant impact on patient outcomes and prognosis. We shed light on the elusive role of the G9a enzyme and many other epigenetic factors in breast cancer recurrence, highlighting its potential as a target for eliminating dormant cancer cells and preventing disease relapse. Through this comprehensive review, we not only emphasise the urgency of unravelling the dynamics of dormant breast cancer cells to improve patient outcomes and advance personalised oncology but also provide a guide for fellow researchers. By clearly outlining the clinical and research gaps surrounding dormant breast cancer cells from a molecular perspective, we aim to inspire further exploration of this critical area, ultimately leading to improved patient care and treatment strategies.

Macrophages upregulate mural cell-like markers and support healing of ischemic injury by adopting functions important for vascular support

Sterile inflammation after injury is important for tissue restoration. In injured human and mouse tissues, macrophages were recently found to accumulate perivascularly. This study investigates if macrophages adopt a mural cell phenotype important for restoration after ischemic injury. Single-cell RNA sequencing of fate-mapped macrophages from ischemic mouse muscles demonstrates a macrophage-toward-mural cell switch of a subpopulation of macrophages with downregulated myeloid cell genes and upregulated mural cell genes, including PDGFRβ. This observation was further strengthened when including unspliced transcripts in the analysis. The macrophage switch was proven functionally relevant, as induction of macrophage-specific PDGFRβ deficiency prevented their perivascular macrophage phenotype, impaired vessel maturation and increased vessel leakiness, which ultimately reduced limb function. In conclusion, macrophages in adult ischemic tissue were demonstrated to undergo a cellular program to morphologically, transcriptomically and functionally resemble mural cells while weakening their macrophage identity. The macrophage-to-mural cell-like phenotypic switch is crucial for restoring tissue function and warrants further exploration as a potential target for immunotherapies to enhance healing.

Decoding Tumor Angiogenesis for Therapeutic Advancements: Mechanistic Insights

Tumor angiogenesis, the formation of new blood vessels within the tumor microenvironment, is considered a hallmark of cancer progression and represents a crucial target for therapeutic intervention. The tumor microenvironment is characterized by a complex interplay between proangiogenic and antiangiogenic factors, regulating the vascularization necessary for tumor growth and metastasis. The study of angiogenesis involves a spectrum of techniques, spanning from biomarker assessment to advanced imaging modalities. This comprehensive review aims to provide insights into the molecular intricacies, regulatory dynamics, and clinical implications of tumor angiogenesis. By delving into these aspects, we gain a deeper understanding of the processes driving vascularization in tumors, paving the way for the development of novel and effective antiangiogenic therapies in the fight against cancer.

From the Mind to the Spine: The Intersecting World of Alzheimer's and Osteoporosis

PURPOSE OF REVIEW

This comprehensive review delves into the intricate interplay between Alzheimer's disease (AD) and osteoporosis, two prevalent conditions with significant implications for individuals' quality of life. The purpose is to explore their bidirectional association, underpinned by common pathological processes such as aging, genetic factors, inflammation, and estrogen deficiency.

RECENT FINDINGS

Recent advances have shown promise in treating both Alzheimer's disease (AD) and osteoporosis by targeting disease-specific proteins and bone metabolism regulators. Monoclonal antibodies against beta-amyloid and tau for AD, as well as RANKL and sclerostin for osteoporosis, have displayed therapeutic potential. Additionally, ongoing research has identified neuroinflammatory genes shared between AD and osteoporosis, offering insight into the interconnected inflammatory mechanisms. This knowledge opens avenues for innovative dual-purpose therapies that could address both conditions, potentially revolutionizing treatment approaches for AD and osteoporosis simultaneously. This review underscores the potential for groundbreaking advancements in early diagnosis and treatment by unraveling the intricate connection between AD and bone health. It advocates for a holistic, patient-centered approach to medical care that considers both cognitive and bone health, ultimately aiming to enhance the overall well-being of individuals affected by these conditions. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Simulation of transvascular transport of nanoparticles in tumor microenvironments for drug delivery applications

Nanomedicine is a promising approach for tumor therapy but penetration is challenged by complex tumor microenvironments. The purpose of this study is to design nanoparticles and analyze their transport in two abnormal microenvironments through a 2-D simulation. Employing a Computational Fluid Dynamics (CFD) approach, tumor vascular-interstitial models were initially simulated, and the impact of nanoparticles on the velocity profile and pressure gradient within the tumor microenvironment was observed. Through meticulous mesh analysis, it was determined that optimal outcomes were achieved using a quadrilateral meshing method for pancreatic tumor and a quad/tri meshing method for hepatic tumor. Results showed an increase in vessel diameter correlated with elevated blood flow velocity, reaching a maximum of 1.40 × 10^-3 m/s with an expanding cell gap. The simulation results for pressure distribution show that as vessel diameter increases, the velocity of nanoparticles in blood increases and decreases the pressure of blood. Intriguingly, distinct fluid flow patterns in pancreatic and hepatic tumors, emphasize how microenvironmental differences, specifically cell pore size, profoundly impact therapeutic agent transport, with implications for drug delivery strategies in cancer therapy. These simulation-based insights enable researchers to anticipate nanofluid behavior in realistic settings. Future work, incorporating immune cells, will enhance the understanding of nanoparticle efficiency in cancer therapy.

Bioactive-Glass-Based Materials with Possible Application in Diabetic Wound Healing: A Systematic Review

Diabetes affected 537 million adults in 2021, costing a total of USD 966 billion dollars in healthcare. One of the most common complications associated with diabetes corresponds to the development of diabetic foot ulcers (DFUs). DFUs affect around 15% of diabetic patients; these ulcers have impaired healing due to neuropathy, arterial disease, infection, and aberrant extracellular matrix (ECM) degradation, among other factors. The bioactive-glass-based materials discussed in this systematic review show promising results in accelerating diabetic wound healing. It can be concluded that the addition of BG is extremely valuable with regard to the wound healing rate and wound healing quality, since BG activates fibroblasts, enhances M1-to-M2 phenotype switching, induces angiogenesis, and initiates the formation of granulation tissue and re-epithelization of the wound. In addition, a higher density and deposition and better organization of collagen type III are seen. This systematic review was made using the PRISMA guideline and intends to contribute to the advancement of diabetic wound healing therapeutic strategies development by providing an overview of the materials currently being developed and their effect in diabetic wound healing in vitro and in vivo.

Canthin-6-One Inhibits Developmental and Tumour-Associated Angiogenesis in Zebrafish

Tumour-associated angiogenesis play key roles in tumour growth and cancer metastasis. Consequently, several anti-angiogenic drugs such as sunitinib and axitinib have been approved for use as anti-cancer therapies. However, the majority of these drugs target the vascular endothelial growth factor A (VEGFA)/VEGF receptor 2 (VEGFR2) pathway and have shown mixed outcome, largely due to development of resistances and increased tumour aggressiveness. In this study, we used the zebrafish model to screen for novel anti-angiogenic molecules from a library of compounds derived from natural products. From this, we identified canthin-6-one, an indole alkaloid, which inhibited zebrafish intersegmental vessel (ISV) and sub-intestinal vessel development. Further characterisation revealed that treatment of canthin-6-one reduced ISV endothelial cell number and inhibited proliferation of human umbilical vein endothelial cells (HUVECs), suggesting that canthin-6-one inhibits endothelial cell proliferation. Of note, canthin-6-one did not inhibit VEGFA-induced phosphorylation of VEGFR2 in HUVECs and downstream phosphorylation of extracellular signal-regulated kinase (Erk) in leading ISV endothelial cells in zebrafish, suggesting that canthin-6-one inhibits angiogenesis independent of the VEGFA/VEGFR2 pathway. Importantly, we found that canthin-6-one impairs tumour-associated angiogenesis in a zebrafish B16F10 melanoma cell xenograft model and synergises with VEGFR inhibitor sunitinib malate to inhibit developmental angiogenesis. In summary, we showed that canthin-6-one exhibits anti-angiogenic properties in both developmental and pathological contexts in zebrafish, independent of the VEGFA/VEGFR2 pathway and demonstrate that canthin-6-one may hold value for further development as a novel anti-angiogenic drug.

Genetic variants in the renin-angiotensin-aldosterone system: Impact on cancer risk, prognosis, and therapeutic directions

Although renin-angiotensin-aldosterone system (RAAS) is known to maintain blood pressure and electrolyte balance, it has recently been linked to a number of biological processes such as angiogenesis, tumorigenesis, metastasis, and cellular proliferation, increasing the risk of cancer development and progression. Multiple genetic variants have been found to affect the genes encoding RAAS components, altering gene transcription and protein expression. This review provides an up-to-date insight into the role of RAAS in carcinogenesis, as well as the impact of RAAS genetic variants on the risk of cancer development, progression, and patient survival and outcomes, as well as response to treatment. This paves the way for the application of precision medicine in cancer risk assessment and management by implementing preventative programs in individuals at risk and guiding the therapeutic direction in cancer patients.

Advanced Technologies of Drug Delivery to the Posterior Eye Segment Targeting Angiogenesis and Ocular Cancer

Retinoblastoma (RB), a childhood retinal cancer is caused due to RB1 gene mutation which affects the child below 5 years of age. Angiogenesis has been proven its role in RB metastasis due to the presence of vascular endothelial growth factor (VEGF) in RB cells. Therefore, exploring angiogenic pathway by inhibiting VEGF in treating RB would pave the way for future treatment. In preclinical studies, anti-VEGF molecule have shown their efficacy in treating RB. However, treatment requires recurrent intra-vitreal injections causing various side effects along with patient nonadherence. As a result, delivery of anti-VEGF agent to retina requires an ocular delivery system that can transport it in a non-invasive manner to achieve patient compliance. Moreover, development of these type of systems are challenging due to the complicated physiological barriers of eye. Adopting a non-invasive or minimally invasive approach for delivery of anti-VEGF agents would not only address the bioavailability issues but also improve patient adherence to therapy overcoming the side effects associated with invasive approach. The present review focuses on the eye cancer, angiogenesis and various novel ocular drug delivery systems that can facilitate inhibition of VEGF in the posterior eye segment by overcoming the eye barriers.

A 1, 4-benzoquinone derivative isolated from Ardisia crispa (Thunb.) A. DC. root suppresses angiogenesis via its angiogenic signaling cascades

The root hexane extract of Ardisia crispa (ACRH), which belongs to the Primulaceae family, has been reported to possess anti-inflammatory, chemopreventive, anti-arthritic, and antiangiogenic activities. In this study, we isolated a p-benzoquinone derivative, 2-methoxy-6-undecyl-1,4-benzoquinone (AC2), from ACRH and investigated its potential antiangiogenic activity in human umbilical vein endothelial cells (HUVECs) and zebrafish embryo models. Prior to this study, AC2 was characterized using 1H NMR spectroscopy and MS. AC2 significantly suppressed HUVEC proliferation in a time-independent manner, with an IC50 value of 1.35 ± 0.05, 1.15 ± 0.02, and 1.00 ± 0.01 µg/mL at 24, 48, and 72 h, respectively. AC2 also induced apoptosis in HUVECs and significantly suppressed their migration, invasion, and tube formation in a concentration-dependent manner. Additionally, AC2 significantly attenuated most of the analyzed protein markers, including pro-MMP-2, VEGF-C, VEGF-D, angiopoietin-2, endothelin-1, fibroblast growth factor (FGF)-1, FGF-2, follistatin, heparin-binding epidermal growth factor-like growth factor (HB-EGF), and hepatocyte growth factor (HGF) at all tested concentrations. Furthermore, AC2 significantly inhibited zebrafish embryo intersegmental vessels (ISVs), confirming its antiangiogenic role. In conclusion, AC2 exhibits a potential anti-angiogenic effect by suppressing several proangiogenic and growth factors. Further studies are needed to investigate their effects on other excessive angiogenic diseases.

Biomechanical stimulation promotes blood vessel growth despite VEGFR-2 inhibition

BACKGROUND

Angiogenesis, or the growth of new vasculature from existing blood vessels, is widely considered a primary hallmark of cancer progression. When a tumor is small, diffusion is sufficient to receive essential nutrients; however, as the tumor grows, a vascular supply is needed to deliver oxygen and nutrients into the increasing mass. Several anti-angiogenic cancer therapies target VEGF and the receptor VEGFR-2, which are major promoters of blood vessel development. Unfortunately, many of these cancer treatments fail to completely stop angiogenesis in the tumor microenvironment (TME). Since these therapies focus on the biochemical activation of VEGFR-2 via VEGF ligand binding, we propose that mechanical cues, particularly those found in the TME, may be a source of VEGFR-2 activation that promotes growth of blood vessel networks even in the presence of VEGF and VEGFR-2 inhibitors.

RESULTS

In this paper, we analyzed phosphorylation patterns of VEGFR-2, particularly at Y1054/Y1059 and Y1214, stimulated via either VEGF or biomechanical stimulation in the form of tensile strains. Our results show prolonged and enhanced activation at both Y1054/Y1059 and Y1214 residues when endothelial cells were stimulated with strain, VEGF, or a combination of both. We also analyzed Src expression, which is downstream of VEGFR-2 and can be activated through strain or the presence of VEGF. Finally, we used fibrin gels and microfluidic devices as 3D microtissue models to simulate the TME. We determined that regions of mechanical strain promoted increased vessel growth, even with VEGFR-2 inhibition through SU5416.

CONCLUSIONS

Overall, understanding both the effects that biomechanical and biochemical stimuli have on VEGFR-2 activation and angiogenesis is an important factor in developing effective anti-angiogenic therapies. This paper shows that VEGFR-2 can be mechanically activated through strain, which likely contributes to increased angiogenesis in the TME. These proof-of-concept studies show that small molecular inhibitors of VEGFR-2 do not fully prevent angiogenesis in 3D TME models when mechanical strains are introduced.

The Supplementation of Sechium edule var. nigrum spinosum (Chayote) Promotes Nrf2-Mediated Antioxidant Protection in Older Adults with Metabolic Syndrome

The aim was to determine the effect of Sechium edule var. nigrum spinosum (chayote) on gene expression related to antioxidant protection mechanisms and the inflammatory process in older adults with metabolic syndrome (MetS). A quasi-experimental study was carried out in a convenience sample of 46 older adults diagnosed with MetS: (i) placebo group (PG; n = 20); (ii) experimental group (EG; n = 26). The clinical, biochemical, anthropometric parameters and SOD, GPx, and CAT enzyme activity, alongside total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), cytokines (IL-6, IL-8 and TNF-α), and mRNA expression of SOD, GPx, CAT, IL-6, IL-8, TNF-α, Nrf2, NFkB p50, and NFkB p65, were measured at baseline and 6 months post-intervention. A statistically significant decrease was observed in TOS (baseline, 28.9 ± 3.6 vs. post, 23.7 ± 3.4, p < 0.01) and OSI (baseline, 24.1 ± 3.8 vs. post, 17.7 ± 4), as well as an increase in IL-6 (baseline, 10.7 ± 1.1 vs. post, 12.3 ± 2, p = 0.03), SOD activity (baseline, 167.1 ± 11.9 vs. post, 180.6 ± 7.6, p < 0.05), CAT activity (baseline, 1.0 ± 0.2 vs. post, 1.3 ± 0.2, p < 0.01), and TAS (baseline, 1.1 ± 0.1 vs. post, 1.4 ± 0.1, p < 0.01) in the EG compared to the PG. Regarding the expression of Nrf2, SOD, and IL-6, the EG showed a significant increase vs. basal levels (47%, 44%, and 43%, respectively). Our findings suggest that Sechium edule supplementation promotes the antioxidant response and decreases oxidative stress via Nrf2.

Sanikovich V, S. Rusanov A, N. Pirogova Y, Boroda A, Rozhkov A, Kemfang Ngowa JD, N. Bagmet L, I. Sekacheva M. Angiogenesis in Lung Cancer: Understanding the Roles of Growth Factors

Research has shown the role of growth factors in lung cancer angiogenesis. Angiogenesis promotes lung cancer progression by stimulating tumor growth, enhancing tumor invasion, contributing to metastasis, and modifying immune system responses within the tumor microenvironment. As a result, new treatment techniques based on the anti-angiogenic characteristics of compounds have been developed. These compounds selectively block the growth factors themselves, their receptors, or the downstream signaling pathways activated by these growth factors. The EGF and VEGF families are the primary targets in this approach, and several studies are being conducted to propose anti-angiogenic drugs that are increasingly suitable for the treatment of lung cancer, either as monotherapy or as combined therapy. The efficacy of the results are encouraging, but caution must be placed on the higher risk of toxicity, outlining the importance of personalized follow-up in the management of these patients.

Angiogenic Microvascular Wall Shear Stress Patterns Revealed Through Three-dimensional Red Blood Cell Resolved Modeling

The wall shear stress (WSS) exerted by blood flowing through microvascular capillaries is an established driver of new blood vessel growth, or angiogenesis. Such adaptations are central to many physiological processes in both health and disease, yet three-dimensional (3D) WSS characteristics in real angiogenic microvascular networks are largely unknown. This marks a major knowledge gap because angiogenesis, naturally, is a 3D process. To advance current understanding, we model 3D red blood cells (RBCs) flowing through rat angiogenic microvascular networks using state-of-the-art simulation. The high-resolution fluid dynamics reveal 3D WSS patterns occurring at sub-endothelial cell (EC) scales that derive from distinct angiogenic morphologies, including microvascular loops and vessel tortuosity. We identify the existence of WSS hot and cold spots caused by angiogenic surface shapes and RBCs, and notably enhancement of low WSS regions by RBCs. Spatiotemporal characteristics further reveal how fluctuations follow timescales of RBC "footprints." Altogether, this work provides a new conceptual framework for understanding how shear stress might regulate EC dynamics in vivo.

Mimicking Molecular Pathways in the Design of Smart Hydrogels for the Design of Vascularized Engineered Tissues

Biomaterials are pivotal in supporting and guiding vascularization for therapeutic applications. To design effective, bioactive biomaterials, understanding the cellular and molecular processes involved in angiogenesis and vasculogenesis is crucial. Biomaterial platforms can replicate the interactions between cells, the ECM, and the signaling molecules that trigger blood vessel formation. Hydrogels, with their soft and hydrated properties resembling natural tissues, are widely utilized; particularly synthetic hydrogels, known for their bio-inertness and precise control over cell-material interactions, are utilized. Naturally derived and synthetic hydrogel bases are tailored with specific mechanical properties, controlled for biodegradation, and enhanced for cell adhesion, appropriate biochemical signaling, and architectural features that facilitate the assembly and tubulogenesis of vascular cells. This comprehensive review showcases the latest advancements in hydrogel materials and innovative design modifications aimed at effectively guiding and supporting vascularization processes. Furthermore, by leveraging this knowledge, researchers can advance biomaterial design, which will enable precise support and guidance of vascularization processes and ultimately enhance tissue functionality and therapeutic outcomes.

Endothelial Senescence and Its Impact on Angiogenesis in Alzheimer's Disease

Endothelial cells are constantly exposed to environmental stress factors that, above a certain threshold, trigger cellular senescence and apoptosis. The altered vascular function affects new vessel formation and endothelial fitness, contributing to the progression of age-related diseases. This narrative review highlights the complex interplay between senescence, oxidative stress, extracellular vesicles, and the extracellular matrix and emphasizes the crucial role of angiogenesis in aging and Alzheimer's disease. The interaction between the vascular and nervous systems is essential for the development of a healthy brain, especially since neurons are exceptionally dependent on nutrients carried by the blood. Therefore, anomalies in the delicate balance between pro- and antiangiogenic factors and the consequences of disrupted angiogenesis, such as misalignment, vascular leakage and disturbed blood flow, are responsible for neurodegeneration. The implications of altered non-productive angiogenesis in Alzheimer's disease due to dysregulated Delta-Notch and VEGF signaling are further explored. Additionally, potential therapeutic strategies such as exercise and caloric restriction to modulate angiogenesis and vascular aging and to mitigate the associated debilitating symptoms are discussed. Moreover, both the roles of extracellular vesicles in stress-induced senescence and as an early detection marker for Alzheimer's disease are considered. The intricate relationship between endothelial senescence and angiogenesis provides valuable insights into the mechanisms underlying angiogenesis-related disorders and opens avenues for future research and therapeutic interventions.

The Tumor Immune Microenvironment in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is a type of kidney cancer that arises from the cells lining the tubes of the kidney. The tumor immune microenvironment (TIME) of ccRCC is a complex interplay of various immune cells, cytokines, and signaling pathways. One of the critical features of the ccRCC TIME is the presence of infiltrating immune cells, including T cells, B cells, natural killer cells, dendritic cells, and myeloid-derived suppressor cells. Among these cells, CD8+ T cells are particularly important in controlling tumor growth by recognizing and killing cancer cells. However, the TIME of ccRCC is also characterized by an immunosuppressive environment that hinders the function of immune cells. Several mechanisms contribute to the immunosuppressive nature of the ccRCC TIME. For instance, ccRCC cells produce cytokines such as interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β), which suppress immune cell activation and promote the differentiation of regulatory T cells (Tregs). Tregs, in turn, dampen the activity of effector T cells and promote tumor growth. In addition, ccRCC cells can express programmed death-ligand 1 (PD-L1), which interacts with the programmed cell death protein 1 (PD-1) receptor on T cells to inhibit their function. In addition, other immune checkpoint proteins, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and lymphocyte activation gene 3 (LAG-3), also contribute to the immunosuppressive milieu of the ccRCC TIME. Finally, the hypoxic and nutrient-poor microenvironment of ccRCC can stimulate the production of immunosuppressive metabolites, such as adenosine and kynurenine, which further impair the function of immune cells. Understanding the complex interplay between tumor cells and the immune system in the ccRCC TIME is crucial for developing effective immunotherapies to treat this disease.

A Brief Review on Cerium Oxide (CeO2NPs)-Based Scaffolds: Recent Advances in Wound Healing Applications

The process of wound healing is complex and involves the interaction of multiple cells, each with a distinct role in the inflammatory, proliferative, and remodeling phases. Chronic, nonhealing wounds may result from reduced fibroblast proliferation, angiogenesis, and cellular immunity, often associated with diabetes, hypertension, vascular deficits, immunological inadequacies, and chronic renal disease. Various strategies and methodologies have been explored to develop nanomaterials for wound-healing treatment. Several nanoparticles such as gold, silver, cerium oxide and zinc possess antibacterial properties, stability, and a high surface area that promotes efficient wound healing. In this review article, we investigate the effectiveness of cerium oxide nanoparticles (CeO₂NPs) in wound healing-particularly the effects of reducing inflammation, enhancing hemostasis and proliferation, and scavenging reactive oxygen species. The mechanism enables CeO₂NPs to reduce inflammation, modulate the immunological system, and promote angiogenesis and tissue regeneration. In addition, we investigate the efficacy of cerium oxide-based scaffolds in various wound-healing applications for creating a favorable wound-healing environment. Cerium oxide nanoparticles (CeO₂NPs) exhibit antioxidant, anti-inflammatory, and regenerative characteristics, enabling them to be ideal wound healing material. Investigations have shown that CeO₂NPs can stimulate wound closure, tissue regeneration, and scar reduction. CeO₂NPs may also reduce bacterial infections and boost wound-site immunity. However, additional study is needed to determine the safety and efficacy of CeO₂NPs in wound healing and their long-term impacts on human health and the environment. The review reveals that CeO₂NPs have promising wound-healing properties, but further study is needed to understand their mechanisms of action and ensure their safety and efficacy.

Endometrial Angiogenesis of Abnormal Uterine Bleeding and Infertility in Patients with Uterine Fibroids-A Systematic Review

Uterine fibroids are the most common benign tumors in women, with abnormal uterine bleeding (AUB) as the main reported symptom. Additionally, an association between fibroids and infertility has been established, especially if the fibroid protrudes in the uterine cavity. Hormonal therapy is associated with side-effects and as well as hysterectomy, which is incompatible with a desire to conceive. To improve treatment, it is essential to unravel the etiology of fibroid-related symptoms. We aim to evaluate endometrial angiogenesis in women with fibroids, with and without AUB, and the influence of pharmaceutical therapies in these patients. Furthermore, we explore the possible role of altered angiogenesis in patients with fibroids and infertility. We performed a systematic review according to PRISMA-guidelines (PROSPERO: CRD42020169061), and included 15 eligible studies. Endometrial expression of vascular endothelial growth factor (VEGF) and adrenomedullin was increased in patients with fibroids. This suggests aberrant angiogenesis, potentially involving disturbed vessel maturation, resulting in immature and fragile vessels. Treatment with gonadotropin-releasing hormone agonist, ulipristal acetate, and continuous oral contraception pills reduced several angiogenic parameters, including VEGF. If infertile and fertile patients with fibroids were compared, a significant decreased expression of the bone morphogenetic protein/Smad-protein pathway was found, possibly caused by the increased expression of transforming growth factor-beta. For future therapeutic development, these different angiogenic pathways could be of interest as possible targets to treat fibroid-related symptoms.

Fine, Vascular Network Formation in Patients with Vein of Galen Aneurysmal Malformation

BACKGROUND AND PURPOSE

A vein of Galen aneurysmal malformation is known to present with recruitment of dural feeders and, in our cohort, a fine, vascular network formation. The vessels we have observed differ from dural vascular recruitment in that they produce a hairlike, collateral network of vessels. We reviewed treatment courses of vein of Galen aneurysmal malformation treatments in a series of 36 cases that displayed a fine, vascular network formation.

MATERIALS AND METHODS

We retrospectively analyzed 36 cases of vein of Galen aneurysmal malformation, including tectal/thalamic AVMs, treated at our center from January 2004 to September 2021, and reviewed fine, vascular network formations in the subarachnoid space and subependymal zone alongside the vein of Galen aneurysmal malformation.

RESULTS

Patients at first endovascular treatment ranged from neonates to 157 months (median age, 4.3 months). Patients with preinterventional fine, vascular network formations were significantly older at the initial angiogram than patients with postinterventional fine, vascular network formations (P < .05). On average, for 20 control choroidal/mural vein of Galen aneurysmal malformations whose treatment course had been completed and in which no plexiform network was visualized, a mean of 2.63 (SD, 1.64) treatments were required to achieve a radiographic cure. For the 36 choroidal/mural vein of Galen aneurysmal malformations whose treatment course had been completed and in which a fine, vascular network formation was visualized, a mean of 5.94 (SD, 2.73) treatments were required to achieve a radiographic cure (P < .01).

CONCLUSIONS

Development of a fine, vascular network formation is an acquired and reversible phenomenon that differs from typical dural vessel recruitment, given the hairlike nature of the network and its rapid onset postinterventionally. It typically resolves after completion of treatment, and this resolution correlates with closure of the vein. We recommend that neurointerventionalists avoid delays in treatment wherever possible to reduce the likelihood of a fine, vascular network formation.

Single-cell RNA sequencing reveals differential expression of EGFL7 and VEGF in giant-cell tumor of bone and osteosarcoma

Dysregulation of angiogenesis is associated with tumor development and is accompanied by altered expression of pro-angiogenic factors. EGFL7 is a newly identified antigenic factor that plays a role in various cancers such as breast cancer, lung cancer, and acute myeloid leukemia. We have recently found that EGFL7 is expressed in the bone microenvironment, but its role in giant-cell tumor of bone (GCTB) and osteosarcoma (OS) is unknown. The aims of this study are to examine the gene expression profile of EGFL7 in GCTB and OS and compare with that of VEGF-A-D and TNFSF11 using single-cell RNA sequencing data. In-depth differential expression analyses were employed to characterize their expression in the constituent cell types of GCTB and OS. Notably, EGFL7 in GCTB was expressed at highest levels in the endothelial cell (EC) cluster followed by osteoblasts, myeloid cells, and chondrocytes, respectively. In OS, EGFL7 exhibited highest expression in EC cell cluster followed by osteoblastic OS cells, myeloid cells 1, and carcinoma associated fibroblasts (CAFs), respectively. In comparison, VEGF-A is expressed at highest levels in myeloid cells followed by OCs in GCTB, and in myeloid cells, and OCs in OS. VEGF-B is expressed at highest levels in chondrocytes in GCTB and in OCs in OS. VEGF-C is strongly enriched in ECs and VEGF-D is expressed at weak levels in all cell types in both GCTB and OS. TNFSF11 (or RANKL) shows high expression in CAFs and osteoblastic OS cells in OS, and osteoblasts in GCTB. This study investigates pro-angiogenic genes in GCTB and OS and suggests that these genes and their expression patterns are cell-type specific and could provide potential prognostic biomarkers and cell type target treatment for GCTB and OS.

SEC is an antiangiogenic virulence factor that promotes Staphylococcus aureus endocarditis independent of superantigen activity

The superantigen staphylococcal enterotoxin C (SEC) is critical for Staphylococcus aureus infective endocarditis (SAIE) in rabbits. Superantigenicity, its hallmark function, was proposed to be a major underlying mechanism driving SAIE but was not directly tested. With the use of S. aureus MW2 expressing SEC toxoids, we show that superantigenicity does not sufficiently account for vegetation growth, myocardial inflammation, and acute kidney injury in the rabbit model of native valve SAIE. These results highlight the critical contribution of an alternative function of superantigens to SAIE. In support of this, we provide evidence that SEC exerts antiangiogenic effects by inhibiting branching microvessel formation in an ex vivo rabbit aortic ring model and by inhibiting endothelial cell expression of one of the most potent mediators of angiogenesis, VEGF-A. SEC's ability to interfere with tissue revascularization and remodeling after injury serves as a mechanism to promote SAIE and its life-threatening systemic pathologies.

APJ/apelin: a promising target for the treatment of retinopathy of prematurity

Retinopathy of prematurity is a noticeable retinal abnormality causing common blindness in children. An uncontrolled retinal vasculature in retinopathy of prematurity inflicts vision loss in numerous children despite the accessibility to a wide range of clinical treatments prescribed for retinopathy of prematurity. Apelin/APJ [class A (rhodopsin-like) G-protein-coupled receptor] signaling regulates retinopathy of prematurity augmented with uncontrolled angiogenesis. Antagonists targeting pathological apelin/APJ-signaling-induced angiogenesis could be effective in attenuating retinopathy of prematurity. The therapeutic proficiency of antagonists in diverse modalities: peptides, bioactive molecules and antibodies, targeting apelin peptides or the APJ receptor is discussed in this review. We hypothesize the antagonists could effectively attenuate the retinal vasculature triggered by apelin/APJ signaling activation governing vision impairment in young children.

Mechanoregulation of Vascular Endothelial Growth Factor Receptor 2 in Angiogenesis

The endothelial cells that compose the vascular system in the body display a wide range of mechanotransductive behaviors and responses to biomechanical stimuli, which act in concert to control overall blood vessel structure and function. Such mechanosensitive activities allow blood vessels to constrict, dilate, grow, or remodel as needed during development as well as normal physiological functions, and the same processes can be dysregulated in various disease states. Mechanotransduction represents cellular responses to mechanical forces, translating such factors into chemical or electrical signals which alter the activation of various cell signaling pathways. Understanding how biomechanical forces drive vascular growth in healthy and diseased tissues could create new therapeutic strategies that would either enhance or halt these processes to assist with treatments of different diseases. In the cardiovascular system, new blood vessel formation from preexisting vasculature, in a process known as angiogenesis, is driven by vascular endothelial growth factor (VEGF) binding to VEGF receptor 2 (VEGFR-2) which promotes blood vessel development. However, physical forces such as shear stress, matrix stiffness, and interstitial flow are also major drivers and effectors of angiogenesis, and new research suggests that mechanical forces may regulate VEGFR-2 phosphorylation. In fact, VEGFR-2 activation has been linked to known mechanobiological agents including ERK/MAPK, c-Src, Rho/ROCK, and YAP/TAZ. In vascular disease states, endothelial cells can be subjected to altered mechanical stimuli which affect the pathways that control angiogenesis. Both normalizing and arresting angiogenesis associated with tumor growth have been strategies for anti-cancer treatments. In the field of regenerative medicine, harnessing biomechanical regulation of angiogenesis could enhance vascularization strategies for treating a variety of cardiovascular diseases, including ischemia or permit development of novel tissue engineering scaffolds. This review will focus on the impact of VEGFR-2 mechanosignaling in endothelial cells (ECs) and its interaction with other mechanotransductive pathways, as well as presenting a discussion on the relationship between VEGFR-2 activation and biomechanical forces in the extracellular matrix (ECM) that can help treat diseases with dysfunctional vascular growth.

COVID-19 and dys-regulation of pulmonary endothelium: implications for vascular remodeling

Coronavirus disease-2019 (COVID-19), the disease caused by severe acute respiratory syndrome-coronavirus-2, has claimed more than 4.4 million lives worldwide (as of 20 August 2021). Severe cases of the disease often result in respiratory distress due to cytokine storm, and mechanical ventilation is required. Although, the lungs are the primary organs affected by the disease, more evidence on damage to the heart, kidney, and liver is emerging. A common link in these connections is the cardiovascular network. Inner lining of the blood vessels, called endothelium, is formed by a single layer of endothelial cells. Several clinical manifestations involving the endothelium have been reported, such as its activation via immunomodulation, endotheliitis, thrombosis, vasoconstriction, and distinct intussusceptive angiogenesis (IA), a unique and rapid process of blood-vessel formation by splitting a vessel into two lumens. In fact, the virus directly infects the endothelium via TMPRSS2 spike glycoprotein priming to facilitate ACE-2-mediated viral entry. Recent studies have indicated a significant increase in remodeling of the pulmonary vascular bed via intussusception in patients with COVID-19. However, the lack of circulatory biomarkers for IA limits its detection in COVID-19 pathogenesis. In this review, we describe the implications of angiogenesis in COVID-19, unique features of the pulmonary vascular bed and its remodeling, and a rapid and non-invasive assessment of IA to overcome the technical limitations in patients with COVID-19.

Epigenetic Regulation of the Vascular Endothelium by Angiogenic LncRNAs

The functional properties of the vascular endothelium are diverse and heterogeneous between vascular beds. This is especially evident when new blood vessels develop from a pre-existing closed cardiovascular system, a process termed angiogenesis. Endothelial cells are key drivers of angiogenesis as they undergo a highly choreographed cascade of events that has both exogenous (e.g., hypoxia and VEGF) and endogenous regulatory inputs. Not surprisingly, angiogenesis is critical in health and disease. Diverse therapeutics target proteins involved in coordinating angiogenesis with varying degrees of efficacy. It is of great interest that recent work on non-coding RNAs, especially long non-coding RNAs (lncRNAs), indicates that they are also important regulators of the gene expression paradigms that underpin this cellular cascade. The protean effects of lncRNAs are dependent, in part, on their subcellular localization. For instance, lncRNAs enriched in the nucleus can act as epigenetic modifiers of gene expression in the vascular endothelium. Of great interest to genetic disease, they are undergoing rapid evolution and show extensive inter- and intra-species heterogeneity. In this review, we describe endothelial-enriched lncRNAs that have robust effects in angiogenesis.

Review and comparative analysis of machine learning-based predictors for predicting and analyzing of anti-angiogenic peptides

Cancer is one of the leading causes of death worldwide and underlying this is angiogenesis that represents one of the hallmarks of cancer. Ongoing effort is already under way in the discovery of anti-angiogenic peptides (AAPs) as a promising therapeutic route by tackling the formation of new blood vessels. As such, the identification of AAPs constitutes a viable path for understanding their mechanistic properties pertinent for the discovery of new anti-cancer drugs. In spite of the abundance of peptide sequences in public databases, experimental efforts in the identification of anti-angiogenic peptides have progressed very slowly owing to its high expenditures and laborious nature. Owing to its inherent ability to make sense of large volumes of data, machine learning (ML) represents a lucrative technique that can be harnessed for peptide-based drug discovery. In this review, we conducted a comprehensive and comparative analysis of ML-based AAP predictors in terms of their employed feature descriptors, ML algorithms, cross-validation methods and prediction performance. Moreover, the common framework of these AAP predictors and their inherent weaknesses are also discussed. Particularly, we explore future perspectives for improving the prediction accuracy and model interpretability, which represents an interesting avenue for overcoming some of the inherent weaknesses of existing AAP predictors. We anticipate that this review would assist researchers in the rapid screening and identification of promising AAPs for clinical use.

Effect of snail mucus on angiogenesis during wound healing

Background: Angiogenesis is the process through which new blood vessels are formed from existing ones. This process plays an important role in supplying the oxygen and nutrients needed for cellular metabolism and eliminating cell debris during wound healing. Snail mucus can bind to several factors that stimulate angiogenesis, including vascular endothelial growth factor, platelet-derived growth factor, and fibroblast growth factor. The aim of this study is to observe changes in angiogenesis during the healing of wounds topically applied with snail mucus. Methods: Punch biopsy was performed on the back of male Wistar rats to obtain four wounds, and different concentrations of snail mucus were applied to each of these wounds. The animals were sacrificed on days 2, 4, and 7 to observe the extent of angiogenesis during wound healing by microscopy. Results: Two-way ANOVA showed differences in number of blood vessels formed (p = 0.00) and day of observation (p = 0.00) between groups. Post hoc Tukey's HSD test showed that 24% snail mucus treatment does not significantly affect wound healing (p = 0.488); by contrast, treatment with 48% and 96% snail mucus demonstrated significant effects on angiogenesis (p = 0.01). Spearman's test showed interactive effects between snail mucus concentration and day of observation on the extent of angiogenesis (p = 0.001, R = 0.946). Conclusion: Topical application of snail mucus gel can increase angiogenesis during wound healing in Wistar rat skin.

Developmental events and cellular changes occurred during esophageal development of quail embryos

The current study focused on the histogenesis of the esophagus in quail embryos. Formation of the gut tube occurred on the 4th day of incubation. Development of the muscular layers occurred in a sequential manner; the inner circular layer on the 7th day, the outer longitudinal layer on the 8th day and the muscularis mucosae on the 9th day. Glandular development began on the 13th day of incubation. The epithelium was pseudostratified columnar that consisted of mucous cells, dendritic cells, and keratinocyte precursors. Epithelial stratification occurred on the 15th day of incubation. We used Mallory trichrome, Weigert-Van Gieson, and Gomori silver stains to visualize fibrous components. Scanned samples showed formation of endoderm and mesoderm on the 5th day of incubation. A layer of myoblasts developed on the 8th day of incubation. Formation of mucosal folds, which contained glandular openings, occurred on the 14th to 17th days of incubation. On the 5th to 8th days of incubation, CD34 and vascular endothelial growth factor (VEGF) positive-mesodermal cells, and telocytes (TCs) were detected. On the 15th day of incubation, CD34 and VEGF positive-telocytes, and fibroblasts, were identified. The current study described the correlations between functional morphology and evolutionary biology.

Telocytes are major constituents of the angiogenic apparatus

The current study investigated role of telocytes (TCs) in angiogenesis during embryonic development of quail using immunohistochemistry (IHC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The angiogenic apparatus consisted of TCs, endothelial cells, and macrophages. TCs were identified morphologically by their telopodes and podoms using TEM and SEM and immunohistochemically using CD34, and vascular endothelial growth factor (VEGF). TCs also expressed CD68. TCs formed a three-dimensional network and established direct contact with blood vessels, sprouting endothelial cells, and active macrophages, while exerting their effect through paracrine signaling. VEGF was also expressed by endothelial cells and macrophages. Matrix metalloproteinase–9 (MMP-9) was expressed by TCs, endothelial cells, and macrophages. In conclusion, the expression of VEGF by TCs, endothelial cells, and macrophages is required for the proliferation and migration of endothelial cells and vascular growth. The expression of MMP-9 by TCs, endothelial cells, and macrophages is essential for the degradation of extracellular matrix (ECM) components during neoangiogenesis. Macrophages may facilitate phagocytosis and elimination of the degraded ECM components.

Anti-angiogenic activity of chloride and potassium channel modulators: repurposing ion channel modulators

Background

Excessive angiogenesis can be the root cause of many pathological conditions. Various types of ion channels are found on the endothelial cells. These ion channels play a vital role in the multi-stepped process of angiogenesis. The study aims to investigate the anti-angiogenic effects of specific ion channel modulators mefloquine (volume-regulated chloride channel blocker), lubiprostone (ClC-2 channel agonist), and 4-aminopyridine (voltage-gated potassium channel blocker).

Results

The anti-angiogenic activity of ion channel modulators was screened by measuring its effects on the area of neovascularization and histopathological studies by in vivo (corneal neovascularization) method and by in vitro assays, endothelial cell proliferation assay, cell migration assay, and matrigel cord-like morphogenesis assay. The test and standard drug (bevacizumab) groups were compared with the control group using one-way ANOVA, followed by post hoc test, and Dunnett’s test to compare the mean of all the groups with the control mean. The results revealed that mefloquine at the dose of 0.6% w/v and 1.0% w/v, lubiprostone at the dose of 0.5% w/v and 1.0% w/v, and 4-aminopyridine at the dose of 2% w/v and 4% w/v showed significant anti-angiogenic property. In the studies on human umbilical vein endothelial cells, the test drugs (100 nM) showed significant inhibition of proliferation, migration, and decrease in network length of cord-like tubes.

Conclusion

The scientific findings indicate that the test drugs have potent anti-angiogenic activity by inhibiting the cell proliferation, inhibiting the cell volume increase, arresting the cell cycle progression and by causing membrane hyperpolarization. The potent anti-angiogenic drugs obtained by repurposing these ion channel modulators, in the further studies, will be able to treat the diseases due to excess angiogenesis from the root cause.

Graphical abstract

When Innate Immunity Meets Angiogenesis-The Role of Toll-Like Receptors in Endothelial Cells and Pulmonary Hypertension

Toll-like receptors serve a central role in innate immunity, but they can also modulate cell function in various non-immune cell types including endothelial cells. Endothelial cells are necessary for the organized function of the vascular system, and part of their fundamental role is also the regulation of immune function and inflammation. In this review, we summarize the current knowledge of how Toll-like receptors contribute to the immune and non-immune functions of the endothelial cells.

New methods for objective angiogenesis evaluation of rat nerves using microcomputed tomography scanning and conventional photography

INTRODUCTION

Nerve regeneration involves multiple processes, which enhance blood supply that can be promoted by growth factors. Currently, tools are lacking to visualize the vascularization patterns in transplanted nerves in vivo. The purpose of this study was to describe three-dimensional visualization of the vascular system in the rat sciatic nerve and to quantify angiogenesis of nerve reconstruction.

MATERIALS AND METHODS

In 12 Lewis rats (weighing 250-300 g), 10 mm sciatic nerve gaps were repaired with ipsilateral reversed autologous nerve grafts. At 12 and 16 weeks of sacrifice, Microfil® contrast compound was injected in the aorta. Nerve autografts (N = 12) and contralateral untreated nerves (N = 12) were harvested and cleared while preserving the vasculature. The amount of vascularization was measured by quantifying the vascular surface area using conventional photography (two-dimensional) and the vascular volume was calculated with microcomputed tomography (three-dimensional). For each measurement, a vessel/nerve area ratio was calculated and expressed in percentages (vessel%).

RESULTS

The vascular volume measured 3.53 ± 0.43% in autografts and 4.83 ± 0.45% vessels in controls at 12 weeks and 4.95 ± 0.44% and 6.19 ± 0.29% vessels at 16 weeks, respectively. The vascular surface area measured 25.04 ± 2.77% in autografts and 26.87 ± 2.13% vessels in controls at 12 weeks, and 28.11 ± 3.47% and 33.71 ± 2.60% vessels at 16 weeks, respectively. The correlation between both methods was statistically significant (p = .049).

CONCLUSIONS

Both methods are considered to successfully reflect the degree of vascularization. Application of this technique could be used to visualize and objectively quantify angiogenesis of the transplanted nerve graft. Moreover, this simple method is easily reproducible and could be extrapolated to any other desired target organ ex vivo in small animals to investigate the vascular network.

Novel chitosan derivative based composite scaffolds with enhanced angiogenesis; potential candidates for healing chronic non-healing wounds

The success of wound healing depends upon the proper growth of vascular system in time in the damaged tissues. Poor blood supply to wounded tissues or tissue engineered grafts leads to the failure of wound healing or rejection of grafts. In present paper, we report the synthesis of novel organosoluble and pro-angiogenic chitosan derivative (CSD) by the reaction of chitosan with 1,3-dimethylbarbituric acid and triethylorthoformate (TEOF). The synthesized material was characterized by FTIR and ¹³C-NMR to confirm the incorporated functional groups and new covalent connectivities. Biodegradability of the synthesized chitosan derivative was tested in the presence of lysozyme and was found to be comparable with CS. The cytotoxicity and apoptosis effect of new derivative was determined against gastric adenocarcinoma (AGS) cells and was found to be non-toxic. The CSD was found to be soluble in majority of organic solvents. It was blended with polycaprolactone (PCL) to form composite scaffolds. From an ex ovo CAM assay, it was noted that CSD stimulated the angiogenesis.

Combined Application of Bevacizumab and Mitomycin C or Bevacizumab and 5-Fluorouracil in Experimental Glaucoma Filtration Surgery

The present study aimed at observing the effect of a single subconjunctival injection of bevacizumab (BVZ) combined with 5-fluorouracil (5-Fu) or mitomycin C (MMC) on the antiscarring effect of glaucoma filtration surgery (GFS). The inhibitory effect of combined BVZ and 5-Fu in retinal pigment epithelial cells on vascular endothelial growth factor (VEGF) levels was demonstrated through in vitro experiments. Combined BVZ and 5-Fu and combined BVZ and MMC inhibited cell cycle, induced apoptosis, and inhibited human umbilical vein endothelial cell migration. Also, the cytotoxicity of combined BVZ and 5-Fu was lower. In animal experiments, the observation of filtering bleb survival, hematoxylin and eosin and Masson staining of filtering bleb scars, and mRNA expression levels of fibrosis markers in filtering blebs showed that combined BVZ and 5-Fu had a better antiscarring effect compared with single drugs; however, the antiscarring effect of combined BVZ and MMC was not significantly different from MMC. Therefore, the findings of this study provided more reference for the clinical use of adjuncts to inhibit scarring after GFS and helped understand the regulatory effect of combined anti-VEGF antibody BVZ and antimetabolites on wound healing more comprehensively.

Expression, purification and functionality of bioactive recombinant human vascular endothelial growth factor VEGF165 in E. coli

Vascular endothelial growth factor (VEGF) is associated with tumour growth and metastasis. Because VEGF is the major player in both angiogenesis and vascular permeability and the most explored factor in angio-inhibitory therapies, many expression procedures have been developed to produce functional VEGF₁₆₅ in convenient yield. In this study, recombinant human VEGF₁₆₅ was cloned and expressed in Escherichia coli (BL21)-DE3 cells and large scale production was performed by fermentation. A high yield of active soluble protein was obtained after protein extraction employing both lysozyme and sonication treatment. Inclusion bodies were also isolated from the cell lysate and subjected to a simple protocol of solubilisation and refolding. Single-step purification was performed using nickel affinity chromatography and the purified proteins were able to recognize monoclonal Anti-poly-His antibody. The biological activity of the VEGF₁₆₅ was successfully tested using the Chicken chorioallantoic membrane assay, wound-healing migration and proliferation assay on human umbilical vein endothelial cells (HUVEC).

Increased putamen hypercapnic vasoreactivity in levodopa-induced dyskinesia

In a rodent model of Parkinson's disease (PD), levodopa-induced involuntary movements have been linked to striatal angiogenesis - a process that is difficult to document in living human subjects. Angiogenesis can be accompanied by localized increases in cerebral blood flow (CBF) responses to hypercapnia. We therefore explored the possibility that, in the absence of levodopa, local hypercapnic CBF responses are abnormally increased in PD patients with levodopa-induced dyskinesias (LID) but not in their nondyskinetic (NLID) counterparts. We used H215O PET to scan 24 unmedicated PD subjects (12 LID and 12 NLID) and 12 matched healthy subjects in the rest state under normocapnic and hypercapnic conditions. Hypercapnic CBF responses were compared to corresponding levodopa responses from the same subjects. Group differences in hypercapnic vasoreactivity were significant only in the posterior putamen, with greater CBF responses in LID subjects compared with the other subjects. Hypercapnic and levodopa-mediated CBF responses measured in this region exhibited distinct associations with disease severity: the former correlated with off-state motor disability ratings but not symptom duration, whereas the latter correlated with symptom duration but not motor disability. These are the first in vivo human findings linking LID to microvascular changes in the basal ganglia.

Vasculogenic potential evaluation of bottom-up, PCL scaffolds guiding early angiogenesis in tissue regeneration

Vascularization is a key factor in the successful integration of tissue engineered (TE) grafts inside the host body. Biological functions of the newly formed tissue depend, in fact, on a reliable and fast spread of the vascular network inside the scaffold. In this study, we propose a technique for evaluating vascularization in TE constructs assembled by a bottom-up approach. The rational, ordered assembly of building blocks (BBs) into a 3D scaffold can improve vessel penetration, and-unlike most current technologies-is compatible with the insertion of different elements that can be designed independently (e.g. structural units, growth factor depots etc.). Poly(ε-caprolactone) scaffolds composed of orderly and randomly assembled sintered microspheres were used to assess the degree of vascularization in a pilot in vivo study. Scaffolds were implanted in a rat subcutaneous pocket model, and retrieved after 7 days. We introduce three quantitative factors as a measure of vascularization: the total percentage of vascularization, the vessels diameter distribution and the vascular penetration depth. These parameters were derived by image analysis of microcomputed tomographic scans of biological specimens perfused with a radiopaque polymer. The outcome of this study suggests that the rational assembly of BBs helps the onset and organization of a fully functional vascular network.

Plants and their active compounds: natural molecules to target angiogenesis

Angiogenesis, or new blood vessel formation, is an important process in the pathogenesis of several diseases and thus has been targeted for the prevention and treatment for many disorders. However, the anti-angiogenic agents that are currently in use are mainly synthetic compounds and humanized monoclonal antibodies, which are either expensive or toxic, thereby limiting their use in many patients. Therefore, it is necessary to identify less toxic, inexpensive, novel and effective anti-angiogenic molecules. Several studies have indicated that natural plant products can meet these criteria. In this review, we discuss the anti-angiogenic properties of natural compounds isolated from plants and the molecular mechanisms by which these molecules act. Finally, we summarize the advantages of using plant products as anti-angiogenic agents. Compared with currently available anti-angiogenic drugs, plant products may not only have similar therapeutic potential but are also inexpensive, less toxic, and easy to administer. However, novel and effective strategies are necessary to improve their bioavailability for clinical use.