VEGF-A(164/165) and PlGF: roles in angiogenesis and arteriogenesis

Hybrid spheroids containing mesenchymal stem cells promote therapeutic angiogenesis by increasing engraftment of co-transplanted endothelial colony-forming cells in vivo

BACKGROUND

Peripheral artery disease is an ischemic vascular disease caused by the blockage of blood vessels supplying blood to the lower extremities. Mesenchymal stem cells (MSCs) and endothelial colony-forming cells (ECFCs) have been reported to alleviate peripheral artery disease by forming new blood vessels. However, the clinical application of MSCs and ECFCs has been impeded by their poor in vivo engraftment after cell transplantation. To augment in vivo engraftment of transplanted MSCs and ECFCs, we investigated the effects of hybrid cell spheroids, which mimic a tissue-like environment, on the therapeutic efficacy and survival of transplanted cells.

METHODS

The in vivo survival and angiogenic activities of the spheroids or cell suspension composed of MSCs and ECFCs were measured in a murine hindlimb ischemia model and Matrigel plug assay. In the hindlimb ischemia model, the hybrid spheroids showed enhanced therapeutic effects compared with the control groups, such as adherent cultured cells or spheroids containing either MSCs or ECFCs.

RESULTS

Spheroids from MSCs, but not from ECFCs, exhibited prolonged in vivo survival compared with adherent cultured cells, whereas hybrid spheroids composed of MSCs and ECFCs substantially increased the survival of ECFCs. Moreover, single spheroids of either MSCs or ECFCs secreted greater levels of pro-angiogenic factors than adherent cultured cells, and the hybrid spheroids of MSCs and ECFCs promoted the secretion of several pro-angiogenic factors, such as angiopoietin-2 and platelet-derived growth factor.

CONCLUSION

These results suggest that hybrid spheroids containing MSCs can serve as carriers for cell transplantation of ECFCs which have poor in vivo engraftment efficiency.

Design, Synthesis, and Biological Evaluation of Indole-2-carboxamides as Potential Multi-Target Antiproliferative Agents

A small set of indole-based derivatives, IV and Va-I, was designed and synthesized. Compounds Va-i demonstrated promising antiproliferative activity, with GI₅₀ values ranging from 26 nM to 86 nM compared to erlotinib's 33 nM. The most potent antiproliferative derivatives-Va, Ve, Vf, Vg, and Vh-were tested for EGFR inhibitory activity. Compound Va demonstrated the highest inhibitory activity against EGFR with an IC₅₀ value of 71 ± 06 nM, which is higher than the reference erlotinib (IC₅₀ = 80 ± 05 nM). Compounds Va, Ve, Vf, Vg, and Vh were further tested for BRAF^V600E inhibitory activity. The tested compounds inhibited BRAF^V600E with IC₅₀ values ranging from 77 nM to 107 nM compared to erlotinib's IC₅₀ value of 60 nM. The inhibitory activity of compounds Va, Ve, Vf, Vg, and Vh against VEGFR-2 was also determined. Finally, in silico docking experiments attempted to investigate the binding mode of compounds within the active sites of EGFR, BRAF^V600E, and VEGFR-2.

VEGF Profile in Early Undifferentiated Arthritis Cohort

Background and Objectives: Early undifferentiated arthritis (UA) is a group of inflammatory joint diseases that are not classified under any specific rheumatic or connective tissue disorder and might evolve into chronic inflammatory arthritis or may be a self-limiting condition. Early recognition and treatment are crucial for the future course of the disease. Vascular endothelial growth factor (VEGF) is an angiogenic regulator that induces the growth of new capillary blood vessels, which are important in joint invasion and destruction during the progression of chronic inflammatory arthritis. The aim of this study was to assess VEGF levels associated with sociodemographic, clinical, laboratory, and ultrasound findings in the early UA patient cohort as well as to evaluate VEGF as a potential prognostic marker for arthritis outcomes. Materials and Methods: Seventy-six patients with inflammatory arthritis in at least one joint, with a duration of arthritis <12 months at the study entry that did not meet any rheumatic disease classification criteria, were enrolled after informed consent was obtained. Patient’s sociodemographic, laboratory data, and clinical disease characteristics were recorded, VEGF levels were measured, and ultrasound (US) of tender and swollen joints was performed. Results: VEGF levels had positive correlation with conventional rheumatic disease activity and diagnostic markers: erythrocyte sedimentation rate (ESR), C−reactive protein (CRP), and rheumatoid factor (RF) (p < 0.05). RF-positive patients had higher VEGF values (p = 0.024). A statistically higher number of patients whose VEGF levels were below the median value presented with active infection (p = 0.046). In patients with a higher number of swollen joints, and a higher score of synovitis and power doppler (PD) seen on US, VEGF levels were statistically significantly higher. Patients who after 12-month follow-up developed rheumatoid arthritis (RA) had statistically higher VEGF levels at baseline compared with those who developed spondyloarthropathies (p = 0.028). Conclusions: This study demonstrated that VEGF levels significantly represented inflammatory processes that were present in the joints (number of swollen joints, synovitis, and PD changes) of the early UA cohort.

VEGF-A controls the expression of its regulator of angiogenic functions, dopamine D2 receptor, on endothelial cells

We have previously demonstrated significant upregulation of dopamine D2 (DAD2) receptor (DRD2) expression on tumor endothelial cells. The dopamine D2 receptors, upon activation, inhibit the proangiogenic actions of vascular endothelial growth factor-A (VEGF-A, also known as vascular permeability factor). Interestingly, unlike tumor endothelial cells, normal endothelial cells exhibit very low to no expression of dopamine D2 receptors. Here, for the first time, we demonstrate that through paracrine signaling, VEGF-A can control the expression of dopamine D2 receptors on endothelial cells via Krüppel-like factor 11 (KLF11)-extracellular signal-regulated kinase (ERK) 1/2 pathway. These results thus reveal a novel bidirectional communication between VEGF-A and DAD2 receptors.

Single-cell analysis of the cellular heterogeneity and interactions in the injured mouse spinal cord

The wound healing process that occurs after spinal cord injury is critical for maintaining tissue homeostasis and limiting tissue damage, but eventually results in a scar-like environment that is not conducive to regeneration and repair. A better understanding of this dichotomy is critical to developing effective therapeutics that target the appropriate pathobiology, but a major challenge has been the large cellular heterogeneity that results in immensely complex cellular interactions. In this study, we used single-cell RNA sequencing to assess virtually all cell types that comprise the mouse spinal cord injury site. In addition to discovering novel subpopulations, we used expression values of receptor-ligand pairs to identify signaling pathways that are predicted to regulate specific cellular interactions during angiogenesis, gliosis, and fibrosis. Our dataset is a valuable resource that provides novel mechanistic insight into the pathobiology of not only spinal cord injury but also other traumatic disorders of the CNS.

Neovascularization of engineered tissues for clinical translation: Where we are, where we should be?

One of the key challenges in engineering three-dimensional tissue constructs is the development of a mature microvascular network capable of supplying sufficient oxygen and nutrients to the tissue. Recent angiogenic therapeutic strategies have focused on vascularization of the constructed tissue, and its integration in vitro; these strategies typically combine regenerative cells, growth factors (GFs) with custom-designed biomaterials. However, the field needs to progress in the clinical translation of tissue engineering strategies. The article first presents a detailed description of the steps in neovascularization and the roles of extracellular matrix elements such as GFs in angiogenesis. It then delves into decellularization, cell, and GF-based strategies employed thus far for therapeutic angiogenesis, with a particularly detailed examination of different methods by which GFs are delivered in biomaterial scaffolds. Finally, interdisciplinary approaches involving advancement in biomaterials science and current state of technological development in fabrication techniques are critically evaluated, and a list of remaining challenges is presented that need to be solved for successful translation to the clinics.

Shuxuening injection, derived from Ginkgo biloba leaf, induced pseudo-allergic reactions through hyperactivation of mTOR

Context: Shuxuening injection (SXNI), derived from the leaf of Ginkgo biloba L. (Ginkgoaceae), is widely used to treat cardio-cerebral vascular system related disease due to the efficacy of dilating the blood vessels and improving the function of microcirculation. Nevertheless, SXNI induces immediate hypersensitivity reactions in clinics and the molecular mechanisms are unknown.Objective: The present study investigates the molecular mechanism of SXNI mediated hypersensitivity reactions.Materials and methods: Naive male ICR mice (n = 10) were administered (i.v.) with negative control combined with Evans blue (EB) (CTL-EB), SXNI (14 or 70 mg/kg) combined with EB (SXNI/1-EB or SXNI/4-EB), vascular leakage was evaluated, ears and lungs were collected for histopathological analysis. In vitro, TSC1 was knockdown in human umbilical vein endothelial cells (HUVECs). HUVECs were incubated with SXNI, and the alterations of endothelial cell permeability were observed. Rapamycin (mTOR inbibitor) was used to investigate SXNI-induced hypersensitivity reactions both in mice and HUVECs.Results: SXNI (70 mg/kg) induced vascular leakage in mice. Slight oedema and microvascular dilation in the ears, and broaden of alveolar septal and monocyte infiltration in the lungs were observed in SXNI (70 mg/kg) treated mice. mTOR inhibitor alleviates SXNI mediated vascular endothelial hyperpermeability both in vitro and in vivo.Discussion and conclusions: SXNI stimulates pseudo-allergic reactions through hyperactivation of mTOR signalling pathway. Our work provides the new molecular mechanism of drug related pseudo-allergic reactions, and a potential drug to prevent and treat SXNI mediated hypersensitivity reactions.

S-glutathionylation, friend or foe in cardiovascular health and disease

Glutathione is a low molecular weight thiol that is present at high levels in the cell. The high levels of glutathione in the cell make it one of the most abundant antioxidants contributing to cellular redox homeostasis. As a general rule, throughout cardiovascular disease and progression there is an imbalance in redox homeostasis characterized by reactive oxygen species overproduction and glutathione underproduction. As research into these imbalances continues, glutathione concentrations are increasingly being observed to drive various physiological and pathological signaling responses. Interestingly in addition to acting directly as an antioxidant, glutathione is capable of post translational modifications (S-glutathionylation) of proteins through both chemical interactions and enzyme mediated events. This review will discuss both the chemical and enzyme-based S-glutathionylation of proteins involved in cardiovascular pathologies and angiogenesis.

Knockout of EGFL6 by CRISPR/Cas9 Mediated Inhibition of Tumor Angiogenesis in Ovarian Cancer

Tumor angiogenesis plays an important role in the progression and metastasis of ovarian cancer. EGFL6 protein is highly expressed in ovarian cancer and has been proposed to play an important role in promoting tumor angiogenesis. Here, a CRISPR/Cas9 system was used to knockout the EGFL6 gene in the ovarian cancer cell line SKOV3, using specific guide RNA targeting the exons of EGFL6. The knockout of EGFL6 markedly inhibited the proliferation, migration, and invasion of SKOV3 cells, as well as promoted apoptosis of tumor cells. In the nude mouse model of ovarian cancer, knockout of EGFL6 remarkably inhibited tumor growth and angiogenesis. The transcript profile assays detected 4,220 differentially expressed genes in the knockout cells, including 87 genes that were correlated to proliferation, migration, invasion, and angiogenesis. Moreover, Western blotting confirmed that EGFL6 knockout downregulated the FGF-2/PDGFB signaling pathway. Thus, the results of this study indicated that EGFL6 could regulate cell proliferation, migration, and angiogenesis in ovarian cancer cells by regulating the FGF-2/PDGFB signaling pathway.

Role of Nrf2 in MALAT1/ HIF-1α loop on the regulation of angiogenesis in diabetic foot ulcer

Diabetic non healing wounds often result in significant morbidity and mortality. The number of effective targets to detect these wounds are meagre. Slow lymphangiogenesis is one of the complex processes involved in impaired healing of wounds. Long non coding RNAs (lncRNAs) have been importantly recognized for their role in pathological conditions. Multiple studies highlighting the role of lncRNAs in the regulation of several biological processes and complex diseases. Herein, we investigated the role of lncRNA Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the progression of diabetic foot ulcer (DFU). We report a significant reduction in the expression of lncRNA MALAT1 in the infected DFU subjects which was positively correlated with the expression of angiogenic factors such as Nrf2, HIF-1α and VEGF. Further, expression of pro-inflammatory markers TNF-α and IL-6 were found to be increased while, the expression of anti-inflammatory marker IL-10 was decreased in infected DFU tissues. Involvement of lncRNA MALAT1 in angiogenesis in EA.hy926 cells was demonstrated by silencing the expression of Nrf2, HIF-1α, and VEGF through interference mediated by MALAT1. In addition, its inflammatory role was demonstrated by decreased expression of TNF-α, IL-6 and not affecting the expression of IL-10. Further, CRISPR-Cas9 knock out of Nrf2 decreased the expression of lncRNA MALAT1, HIF-1α and VEGF which revealed the association of Nrf2 in regulating MALAT1/HIF-1α loop through positive feedback mechanism. Collectively, our results suggested the role of Nrf2 on MALAT1/HIF-1α loop in the regulation of angiogenesis, which could act as a novel target in the treatment of diabetic wounds.

PLGF-1 contained in normal wound myofibroblast-derived microvesicles stimulated collagen production by dermal fibroblasts

During the last stages of wound healing, myofibroblasts differentiate mainly from fibroblasts. Myofibroblasts from normal skin wounds (Wmyo) can communicate with its surrounding using secreted factors. They also have the capacity to produce microvesicles (MVs), a type of extracellular vesicles, as mediators of intercellular communication. MVs cargo are potentially capable of regulating the behavior of targeted cells and tissues. The aim of this study is to evaluate the effect of Wmyo-derived MVs on dermal fibroblasts and to determine the responsible signaling molecule. Microvesicles were obtained from culture media of myofibroblasts and characterized using protein quantification, dynamic light scattering and transmission electron microscopy. Uptake of fluorescent MVs in fibroblasts was assessed by flow cytometry. Cytokines concentrations were quantified in MV samples by a multiplex ELISA. Different concentration of MVs or a selected cytokine were used as treatments over fibroblasts culture for 5 days. Following the treatments, parameters linked to the extracellular matrix were studied. Lastly, the selected cytokine was neutralized within MVs before evaluating collagen production. We showed that Wmyo derived-MVs were internalized by dermal fibroblasts. Cytokine array analysis revealed that a large amount of placental growth factor 1 (PLGF-1) (0.88 ± 0.63 pg/μg proteins in MVs) could be detected in MVs samples. Cutaneous fibroblasts treated with MVs or PLGF-1 showed significantly stimulated procollagen I level production (Fold change of 1.80 ± 0.18 and 2.07 ± 0.18, respectively). Finally, the neutralization of PLGF-1 in MVs significantly inhibited the production of procollagen I by fibroblasts. Our study shows that Wmyo derived-MVs are involved in intercellular communication by stimulating collagen production by fibroblasts during wound healing. This effect is possibly attained through PLGF-1 signalling. These findings represent a promising opportunity to gain insight into how MVs and Wmyo may mediate the healing of a skin wound.

The role of oxygen transport in atherosclerosis and vascular disease

Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system-the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.

Sepsis-associated acute respiratory distress syndrome in individuals of European ancestry: a genome-wide association study

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a lung inflammatory process caused mainly by sepsis. Most previous studies that identified genetic risks for ARDS focused on candidates with biological relevance. We aimed to identify novel genetic variants associated with ARDS susceptibility and to provide complementary functional evidence of their effect in gene regulation.

METHODS

We did a case-control genome-wide association study (GWAS) of 1935 European individuals, using patients with sepsis-associated ARDS as cases and patients with sepsis without ARDS as controls. The discovery stage included 672 patients admitted into a network of Spanish intensive care units between January, 2002, and January, 2017. The replication stage comprised 1345 individuals from two independent datasets from the MESSI cohort study (Sep 22, 2008-Nov 30, 2017; USA) and the VISEP (April 1, 2003-June 30, 2005) and MAXSEP (Oct 1, 2007-March 31, 2010) trials of the SepNet study (Germany). Results from discovery and replication stages were meta-analysed to identify association signals. We then used RNA sequencing data from lung biopsies, in-silico analyses, and luciferase reporter assays to assess the functionallity of associated variants.

FINDINGS

We identified a novel genome-wide significant association with sepsis-associated ARDS susceptibility (rs9508032, odds ratio [OR] 0·61, 95% CI 0·41-0·91, p=5·18 × 10^-8) located within the Fms-related tyrosine kinase 1 (FLT1) gene, which encodes vascular endothelial growth factor receptor 1 (VEGFR-1). The region containing the sentinel variant and its best proxies acted as a silencer for the FLT1 promoter, and alleles with protective effects in ARDS further reduced promoter activity (p=0·0047). A literature mining of all previously described ARDS genes validated the association of vascular endothelial growth factor A (VEGFA; OR 0·55, 95% CI 0·41-0·73; p=4·69 × 10^-5).

INTERPRETATION

A common variant within the FLT1 gene is associated with sepsis-associated ARDS. Our findings support a role for the vascular endothelial growth factor signalling pathway in ARDS pathogenesis and identify VEGFR-1 as a potential therapeutic target.

FUNDING

Instituto de Salud Carlos III, European Regional Development Funds, Instituto Tecnológico y de Energías Renovables.

Batroxobin accelerated tissue repair via neutrophil extracellular trap regulation and defibrinogenation in a murine ischemic hindlimb model

Batroxobin, isolated from Bothrops moojeni, is a defibrinogenating agent used as a thrombin-like serine protease against fibrinogen for improving microcirculation. Here, we investigated whether, and if so, how batroxobin restores ischemic tissue injury in terms of anti-inflammatory effects. In an in vitro flow cytometry assay for human neutrophil extracellular traps (NETs), batroxobin (DF-521; Defibrase) inhibited human NETs induced by tumor necrosis factor-α (TNF-α) in the presence of human fibrinogen. Next, the effect of batroxobin was investigated by immunohistochemistry of the anterior tibial muscle (ATM) in an ischemic hindlimb model using C57BL/6J mice intraperitoneally injected with DF-521 versus the saline control. NETs and fibrinogen deposition in the ischemic ATM decreased in DF-521-treated mice on day 2 after ischemia. Meanwhile, reverse transcription-quantitative PCR assay of the ischemic ATM unveiled continuous downregulation in the expression of the genes; Tnf-α and nitric oxide synthase2 (Nos2) with hypoxia-inducible factor-1α (Hif-1α) and vascular endothelial growth factor-a (Vegf-a) from day 3 to day 7, but the upregulation of arginase-1 (Arg-1) and placental growth factor (Plgf) with myogenin (Myog) on day 7. Daily intraperitoneal DF-521 injection for the initial 7 days into mice with ischemic hindlimbs promoted angiogenesis and arteriogenesis on day 14. Moreover, DF-521 injection accelerated myofiber maturation after day 14. Laser doppler imaging analysis revealed that blood perfusion in DF-521-injected mice significantly improved on day 14 versus the saline control. Thus, DF-521 improves microcirculation by protecting NETs with tissue defibrinogenation, thereby protecting against severe ischemic tissue injury and accelerating vascular and skeletal muscular regeneration. To our knowledge, batroxobin might be the first clinically applicable NET inhibitor against ischemic diseases.

Plasma Placental Growth Factor Concentrations Are Elevated Well in Advance of Type 2 Diabetes Mellitus Onset: Prospective Data From the WHS

Background

Pathologic angiogenesis is a hallmark of type 2 diabetes mellitus (T2DM) microvascular complications and may modulate adipogenesis and precede the onset of clinical diabetes mellitus; however, longitudinal data are unavailable. Placental growth factor is a potent proangiogenic factor that stimulates the formation of mature and durable vessels but is understudied in human diseases.

Methods and Results

We conducted a prospective case‐cohort study of baseline placental growth factor and incident T2DM within the WHS (Women's Health Study). A random sample of incident T2DM cases (n=491) occurring over a 15‐year follow‐up period was selected and compared with a reference subcohort (n=561). Case subjects were matched to the reference risk set on 5‐year age groups and race. All subjects in this analysis were required to have a hemoglobin A_1c <6.5% at WHS enrollment. Median baseline levels of placental growth factor were higher in case subjects compare to the reference subcohort (18.0 pg/mL versus 17.2 pg/mL) but were only weakly correlated with glycemic measures and not associated with obesity. The risk of diabetes mellitus increased across placental growth factor quartile in the base model (hazard ratios, 1.00, 1.14, 1.46, and 2.14; P‐trend<0.001) and in multivariable‐adjusted models accounting for clinical T2DM risk factors (hazard ratios, 1.00, 1.17, 1.45, and 2.61; P‐trend<0.001). These findings were not substantially altered by further adjustment for high‐sensitivity C‐reactive protein, hemoglobin A_1c, or fasting insulin and remained robust in sensitivity analyses excluding those diagnosed within 2 years of enrollment and those with baseline hemoglobin A_1c ≥6.0%.

Conclusions

Elevated placental growth factor levels are associated with future T2DM independent of traditional risk factors, measures of glycemia, insulin resistance, and high‐sensitivity C‐reactive protein. These prospective data suggest that pathologic angiogenesis may occur well before the clinical onset of T2DM and thus may have relevance to vascular complications of this disease.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000479.

The dynamics of monocytes in the process of collateralization

Collateralization is an important way for patients with coronary heart disease to supply blood flow to the ischemic area. At present, research on the mechanism of collateral circulation mainly focuses on the inflammatory response. Monocytes are the kernel of inflammatory response during arteriogenesis. Therefore, we reviewed the recent developments in this field in terms of the dynamic changes of monocytes during collateralization. We searched and scanned PubMed for the following terms until November 2018: collateral, collateralization, monocyte, macrophage, and arteriogenesis. Articles were obtained and examined to figure out the dynamics of monocytes in the progress of collateralization. Substantial research shows that recruitment, infiltration, and phenotypic transformation of monocytes can affect function in various ways, respectively. Mechanical or chemical factors that can produce effects on collateral development may be due partly to impact on dynamics of monocytes. Although mechanisms of dynamics of monocytes during arteriogenesis are not elucidated clearly, there is no doubt that deeper exploration of the underlying mechanisms will contribute to pharmaceutical development aiming for promoting collateral development.

Different effects of various anti-angiogenic treatments in an experimental mouse model of retinopathy of prematurity

BACKGROUND

Anti-vascular endothelial growth factor (VEGF) drugs are an option for the treatment of retinopathy of prematurity (ROP). Blocking of other angiogenic factors is also of interest. We therefore investigated in which effects would result blocking of placental growth factor (PlGF).

METHODS

C57BL/6 mice were exposed to 75% oxygen from P7 to P12. Intravitreal injections were performed at P12. Mice of control groups remained untouched after oxygen treatment, or phosphate buffered saline or neutral IgG molecules were injected. In the treatment groups, antibodies against VEGF or PlGF, a mixture of anti-VEGF and anti-PlGF, aflibercept or sunitinib were injected. On P17, electroretinographic (ERG) measurements were performed. Avascular zones and neovascularization were evaluated in retinal flat-mounts. Results are expressed as percent of total retinal area (median with median absolute deviation, MAD).

RESULTS

Eyes of control groups showed similar neovascularization (1.4-3.3%, MAD 0.4-0.9%). Neovascularization was significantly less (0.5-0.7%, MAD 0.1-0.3%) in all treatment groups. Avascular zones in the retinas of control groups showed similar values (18.3-25.7%, MAD 4.8-8.8%). Avascular zones were significantly reduced down to 3.6 ± 1.3% after anti-VEGF injection, but they were not reduced significantly in the other treatment groups (13.3-22%, MAD 3.6-6.1%). ERG measurements did not reveal significant differences between the controls and the treatment groups.

CONCLUSIONS

Blocking of PlGF or injection of sunitinib results in a similar inhibition of neovascularization as by anti-VEGF treatment in the mouse model of ROP. However, physiological angiogenesis that occurs after anti-VEGF treatment is blocked by anti-PlGF or sunitinib treatment, indicating that pathological neovascularization may follow different pathways than physiological angiogenesis.

Vasa Vasorum Angiogenesis: Key Player in the Initiation and Progression of Atherosclerosis and Potential Target for the Treatment of Cardiovascular Disease

Plaque microvascularization and increased endothelial permeability are key players in the development of atherosclerosis, from the initial stages of plaque formation to the occurrence of acute cardiovascular events. First, endothelial dysfunction and increased permeability facilitate the entry of diverse inflammation-triggering molecules and particles such as low-density lipoproteins into the artery wall from the arterial lumen and vasa vasorum (VV). Recognition of entering particles by resident phagocytes in the vessel wall triggers a maladaptive inflammatory response that initiates the process of local plaque formation. The recruitment and accumulation of inflammatory cells and the subsequent release of several cytokines, especially from resident macrophages, stimulate the expansion of existing VV and the formation of new highly permeable microvessels. This, in turn, exacerbates the deposition of pro-inflammatory particles and results in the recruitment of even more inflammatory cells. The progressive accumulation of leukocytes in the intima, which trigger proliferation of smooth muscle cells in the media, results in vessel wall thickening and hypoxia, which further stimulates neoangiogenesis of VV. Ultimately, this highly inflammatory environment damages the fragile plaque microvasculature leading to intraplaque hemorrhage, plaque instability, and eventually, acute cardiovascular events. This review will focus on the pivotal roles of endothelial permeability, neoangiogenesis, and plaque microvascularization by VV during plaque initiation, progression, and rupture. Special emphasis will be given to the underlying molecular mechanisms and potential therapeutic strategies to selectively target these processes.

Decellularized heart ECM hydrogel using supercritical carbon dioxide for improved angiogenesis

Initial angiogenesis within the first 3 days is critical for healing ischemic diseases such as myocardial infarction. Recently, decellularized extracellular matrix (dECM) has been reported to provide tissue-derived ECM components and can be used as a scaffold for cell delivery for angiogenesis in tissue engineering. Decellularization by various detergents such as sodium dodecyl sulfate (SDS) and triton X-100 can remove the cell nuclei in tissue organs. However, this leads to ECM structure denaturation, decreased presence of various ECM proteins and cytokines, and loss of mechanical properties. To overcome these limitations, in this study, we developed a supercritical carbon dioxide and ethanol co-solvent (scCO₂-EtOH) decellularization method, which is a detergent-free system that prevents ECM structure disruption and retains various angiogenic proteins in the heart dECM, and tested on rat heart tissues. The heart tissue was placed into the scCO₂ reactor and decellularized at 37 °C and 350 bar. After scCO₂-EtOH treatment, the effects were evaluated by DNA, collagen, and glycosaminoglycan (GAG) quantification and hematoxylin and eosin and immunofluorescence staining to determine the absence of nucleic acids and preservation of heart ECM components. Similar to the native group, the scCO₂-EtOH group contained more ECM components such as collagen, GAGs, collagen I, laminin, and fibronectin and angiogenic factors including vascular endothelial growth factor, fibroblast growth factor, and platelet-derived growth factor and others in comparison to the detergent group. In addition, to estimate angiogenesis of the dECM hydrogels, the neutralized dECM solution was injected in a rat subcutaneous layer (n = 6 in each group: collagen, scCO₂-EOH, and detergent group), after which the solution naturally formed gelation in the subcutaneous layer. After 3 days, the gels were harvested and estimated by immunofluorescence staining and the ImageJ program for angiogenesis analysis. Consequently, blood vessel formation and density of vWF and α-SMA in the scCO₂-EtOH group were significantly greater than that in the collagen group. Here we suggest that heart-derived decellularized extracellular matrix (dECM) with scCO₂-EtOH treatment is a highly promising angiogenic material for healing in ischemic disease.

STATEMENT OF SIGNIFICANCE

Supercritical carbon dioxide (scCO₂) in a supercritical phase has low viscosity and high diffusivity between gas and liquid properties and is known to be affordable, non-toxic, and eco-friendly. Therefore, scCO₂ extraction technology has been extensively used in commercial and industrial fields. Recently, decellularized extracellular matrix (dECM) was applied to tissue engineering and regenerative medicine as a scaffold, therapeutic material, and bio-ink for 3D printing. Moreover, the general decellularization method using detergents has limitations including eliminating tissue-derived ECM components and disrupting their structures after decellularization. To overcome these limitations, heart tissues were treated with scCO₂-EtOH for decellularization, resulting in preserving of tissue due to the various ECM and angiogenic factors derived. In addition, initiation of angiogenesis was highly induced even after 3 days of injection.

Influences of placental growth factor on mouse retinal vascular development

BACKGROUND

Placental growth factor (PGF) is important for wound-healing and vascular collaterogenesis. PGF deficiency is associated with preeclampsia, a hypertensive disease of human pregnancy. Offspring born to preeclamptic mothers display cognitive impairments and brain vascular and neurostructural deviations. Low PGF production during development may contribute to alterations in offspring cerebrovascular beds. Retina is a readily accessible part of the central nervous system with a well-described pattern of vascular development in mice. Impacts of PGF deficiency were addressed during mouse retinal vascularization.

RESULTS

Retinal vessels were compared between Pgf^-/- and congenic C57BL/6 (B6) mice. PGF deficiency altered neonatal retinal vascularization patterns. Some anatomic alterations persisted into adulthood, particularly in males. Greater arterial wall collagen IV expression was found in adult Pgf^-/- females. Pregnancy (studied in adult females at gestational days 11.5 or 18.5) induced subtle changes upon the mother's retinal vasculature but these pregnancy-induced changes did not differ between genotypes. Significant sex-related differences occurred between adult male and female B6 although sexually dimorphic retinal vascular differences were absent in B6 neonates.

CONCLUSIONS

Overall, PGF has a role in retinal vascular angiogenesis and vessel organization during development but does not affect retinal vessel adaptations in adult females during pregnancy. Developmental Dynamics 246:700-712, 2017. © 2017 Wiley Periodicals, Inc.

Effect of Cytokines on the Formation Tube-Like Structures by Endothelial Cells in the Presence of Trophoblast Cells

Despite ample data on cytokine secretion in the uteroplacental interface, the influence of microenvironment cells, in particular, trophoblast cells on angiogenesis and the role of cytokines in this process remain poorly studied. We studied the influence of cytokines on the formation of tube-like structures by endothelial cells in the presence of trophoblast cells and showed that trophoblast cells suppressed the angiogenic potential of endothelial cells. Antiangiogenic cytokines IFN-γ, IL-10, TNF-α, and TGFβ via modulation of trophoblast cells stimulated the formation of tube-like structures by endothelial cells. In the co-culture of endothelial and trophoblast cells, the effects of cytokines changed and they gained additional regulatory functions.

The Role of Vascular Endothelial Growth Factor in Small-airway Remodelling in a Rat Model of Chronic Obstructive Pulmonary Disease

Small-airway remodelling is one of the most remarkable pathological features of chronic obstructive pulmonary disease (COPD), in which angiogenesis plays a critical role that contributes to disease progression. The endothelial cell-specific mitogen vascular endothelial growth factor (VEGF), as well as its receptors, VEGFR1, VEGFR2, are thought to be the major mediators of pathological angiogenesis, and sunitinib exhibits anti-angiogenesis property through VEGF blockage and has been widely used to treat various cancers. In our study, Sprague-Dawley rats were subjected to lipopolysaccharide (LPS) injection and cigarette smoke (CS) inhalation to induce COPD, following sunitinib administration was conducted. Haematoxylin-eosin, Masson staining and immunostaining analysis were used to evaluate the pathological changes; quantitative real-time PCR and enzyme-linked immunosorbent assay were performed to provide more compelling data on the function of VEGF, VEGFR1, VEGFR2 in angiogenesis. Sunitinib treatment was associated with less angiogenesis in small-airway remodelling with a slightly disordered lung architecture, and lower expression level of VEGF, VEGFR1, VEGFR2. Overall, our results indicate that VEGF is a vital important factor that contributes to the small-airway remodelling in a rat model of COPD through promoting angiogenesis, which mainly depend on the specific binding between VEGF and VEGFR1 and can be effectively attenuated by sunitinib.

Cardioprotective activity of placental growth factor combined with oral supplementation of l-arginine in a rat model of acute myocardial infarction

OBJECTIVE

Exogenous administration of placental growth factor (PlGF) stimulates angiogenesis and improves ventricular remodeling after acute myocardial infarction (AMI), and supplementation with l-arginine ameliorates endothelial function. The objective of the present study was to compare the cardioprotective effects of combination therapy of PlGF and l-arginine with those of direct administration of PlGF alone in a rat model of AMI.

MATERIALS AND METHODS

Fifty male Sprague Dawley rats were randomly divided into five groups: sham group, normal saline group, l-arginine group, PlGF group, and combination group (PlGF + l-arginine). An AMI rat model was established by ligation of the left anterior descending of coronary arteries. After 4 weeks of postligation treatment, cardiac function, scar area, angiogenesis and arteriogenesis, myocardial endothelial nitric oxide synthase (eNOS) and collagen I protein content, and plasma concentration of brain natriuretic peptide (BNP) were studied. Echocardiography, Masson's staining, immunohistochemical analyses, Western blot, and enzyme-linked immunosorbent assay were performed.

RESULTS

Left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), and capillary and arteriole densities were higher in the PlGF group than in the normal saline group (P<0.01). Scar area, collagen I protein content, and plasma concentration of BNP were decreased in the PlGF group (P<0.01). Myocardial eNOS protein level was elevated in the l-arginine group and PlGF + l-arginine group (P<0.01). Compared with the PlGF group, LVEF, LVFS, myocardial eNOS, and capillary and arteriole densities were higher in the combination group (P<0.01). Scar area, content of collagen I protein, and plasma concentration of BNP were reduced in the combination group (P<0.01).

CONCLUSION

Exogenous administration of PlGF stimulates angiogenesis and improves cardiac function. l-arginine increases the expression of the eNOS protein. PlGF and l-arginine have a more pronounced, synergistic protective effect on myocardial protection compared with that of exogenous PlGF therapy alone.

Anomalous Origin of the Left Vertebral Artery from the Aortic Arch

Anatomic anomalies of the aortic arch have implications for clinical practice if their significance is understood. Our case study involves a cadaveric finding of the left vertebral artery originating directly from the aortic arch. Although this anatomical variation has been documented, the prevalence of this anomaly may be generally underestimated. After noting this anomaly, we analyzed 27 cases and found that four female cadavers had the left vertebral artery originating from the aortic arch rather than the left subclavian artery. With a prevalence rate of 14.8%, it would seem that this anomaly is more significant than previously thought, which could have implications for surgical practice.

Discovery of pan-VEGF inhibitory peptides directed to the extracellular ligand-binding domains of the VEGF receptors

Receptor tyrosine kinases (RTKs) are key molecules in numerous cellular processes, the inhibitors of which play an important role in the clinic. Among them are the vascular endothelial growth factor (VEGF) family members and their receptors (VEGFR), which are essential in the formation of new blood vessels by angiogenesis. Anti-VEGF therapy has already shown promising results in oncology and ophthalmology, but one of the challenges in the field is the design of specific small-molecule inhibitors for these receptors. We show the identification and characterization of small 6-mer peptides that target the extracellular ligand-binding domain of all three VEGF receptors. These peptides specifically prevent the binding of VEGF family members to all three receptors and downstream signaling but do not affect other angiogenic RTKs and their ligands. One of the selected peptides was also very effective at preventing pathological angiogenesis in a mouse model of retinopathy, normalizing the vasculature to levels similar to those of a normal developing retina. Collectively, our results suggest that these peptides are pan-VEGF inhibitors directed at a common binding pocket shared by all three VEGFRs. These peptides and the druggable binding site they target might be important for the development of novel and selective small-molecule, extracellular ligand-binding inhibitors of RTKs (eTKIs) for angiogenic-dependent diseases.

Expressions of VEGF-A and VEGFR-2 in placentae from GDM pregnancies

BACKGROUND

Gestational diabetes mellitus (GDM) is one of the most common medical complications of pregnancy, and has important health implications for mother and child. Changes in the fetoplacental vessels may predict those in the vasculature of the developing fetus, as these have been implicated in the pathogenesis of human GDM. This study aimed to determine the differences in the localization and expression level of VEGFA and VEGFR2 between placentas of women with GDM and placentas of normal pregnancies, which is the first step in elucidating the possible roles of VEGFA and VEGFR2 in the altered uteroplacental function resulting from maternal hyperglycaemia and ultimately in the manifestation of GDM.

METHODS

The expressions of VEGFA and VEGFR2 mRNA and protein in 20 samples from each group were analyzed by real-time PCR, immunohistochemistry and Western blot. The placental blood barrier and angiogenesis were observed by the transmission electron microscopy (TEM) in10 GDM samples and ten controls.

RESULTS

The expression levels of VEGFA and VEGFR2 mRNA and protein were significantly decreased in the GDM group (P < 0.05 or 0.01). Immunohistochemical analysis showed the reduced expression of VEGFA and VEGFR2 protein in GDM-affected placental tissues, and the degenerative alterations of the terminal villi vascular.

CONCLUSION

The expressions of VEGFA and VEGFR-2 mRNAs and protein were reduced in GDM-affected placental tissues, suggesting that maternal GDM affects the pathophysiological function of placentas.

Association between Placental Lesions, Cytokines and Angiogenic Factors in Pregnant Women with Preeclampsia

Preeclampsia (PE) is considered the leading cause of maternal and perinatal morbidity and mortality. The placenta seems to play an essential role in this disease, probably due to factors involved in its formation and development. The present study aimed to investigate the association between placental lesions, cytokines and angiogenic factors in pregnant women with preeclampsia (PE). We evaluated 20 normotensive pregnant women, 40 with early-onset PE and 80 with late-onset PE. Placental samples were analyzed for histopathology, immunohistochemistry and determination of granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-10 (IL-10), transforming growth factor-beta 1 (TGF-β₁), tumor necrosis factor-alpha (TNF-α), placental growth factor (PlGF), vascular endothelial growth factor (VEGF), fms-like tyrosine-kinase-1 (Flt-1) and endoglin (Eng) levels. Higher percentages of increased syncytial knots and increased perivillous fibrin deposits, and greater levels of TNF-α, TGF-β1and Flt-1 were detected in placentas from early-onset PE. Levels of IL-10, VEGF and PlGF were decreased in PE versus normotensive placentas. Both the TNF-α/IL-10 and sFlt-1/PlGF ratios were higher in placental homogenate of early-onset PE than late-onset PE and control groups. The more severe lesions and the imbalance between TNF-α/IL-10 and PlGF/sFlt-1 in placentas from early-onset PE allows differentiation of early and late-onset PE and suggests higher placental impairment in early-onset PE.

Vascularization of plastic calcium phosphate cement in vivo induced by in-situ-generated hollow channels

Despite calcium phosphate cement (CPC) is promising for bone repair therapy, slow biodegradation and insufficient vascularization in constructs negatively impacts its clinical application. A self-setting CPC composited with gelatin fiber is investigated to test the utility of this tissue engineering strategy to support rapid and extensive vascularization process. The interconnected hollow channels in CPC are formed after dissolution of gelatin fibers in vivo. The CPC-gelatin samples exhibit relatively decent/enhanced mechanical property, compared to the control. When implanted in vivo, the pre-established vascular networks in material anastomose with host vessels and accelerate vascular infiltration throughout the whole tissue construct. Different channel sizes induce different vascularization behaviors in vivo. Results indicate that the channel with the size of 250μm increases the expression of the representative angiogenic factors HIF1α, PLGF and migration factor CXCR4, which benefit the formation of small vessels. On the other hand, the channel with the size of 500μm enhances VEGF-A expression, which benefit the development of large vessels. Notably, the intersection area of channels has high invasive, sprouting and vasculogenesis potential under hypoxic condition, because more HIF1α-positive cells are observed there. Observation of the CD31-positive lumen in the border of scaffold indicates the ingrowth of blood vessels from its host into material through channel, benefited from gradually increased HIF1α expression. This kind of material was suggested to promote the effective application of bone regeneration through the combination of in situ self-setting, plasticity, angiogenesis, and osteoconductivity.

Interstitial Outburst of Angiogenic Factors During Skeletal Muscle Regeneration After Acute Mechanical Trauma

Angiogenesis is a key event during tissue regeneration, but the intimate mechanisms controlling this process are still largely unclear. Therefore, the cellular and molecular interplay along normal tissue regeneration should be carefully unveiled. To this matter, we investigated by xMAP assay the dynamics of some angiogenic factors known to be involved in tissue repair, such as follistatin (FST), Placental Growth Factor-2 (PLGF-2), epidermal growth factor (EGF), betacellulin (BTC), and amphiregulin (AREG) using an animal model that mimics acute muscle contusion injuries. In situ immunofluorescence was used for the evaluation and tissue distribution of their cellular sources. Tissue levels of explored factors increased significantly during degeneration and inflammatory stage of regeneration, peaking first week postinjury. However, except for PLGF-2 and EGF, their levels remained significantly elevated after the inflammatory process started to fade. Serum levels were significantly increased only after 24 h for AREG and EGF. Though, for all factors except FST, the levels in injured samples did not correlate with serum or contralateral tissue levels, excluding the systemic influence. We found significant correlations between the levels of EGF and AREG, BTC, FST and FST and AREG in injured samples. Interstitial cells expressing these factors were highlighted by in situ immunolabeling and their number correlated with measured levels dynamics. Our study provides evidence of a dynamic level variation along the regeneration process and a potential interplay between selected angiogenic factors. They are synthesized, at least partially, by cell populations residing in skeletal muscle interstitium during regeneration after acute muscle trauma.

Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The 'response to microorganisms' was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the 'neuron projection morphogenesis' process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis', which have been never anticipated in ALI pathogenesis, promotes lung-protective effects of LVT with high levels of PEEP.

Cell type- and tumor zone-specific expression of pVEGFR-1 and its ligands influence colon cancer metastasis

Background

Detailed knowledge of the essential pro-angiogenic biomolecules, the vascular endothelial growth factor (VEGF) family and its receptors, in the characteristically heterogeneous tumor tissue is a pre-requisite for an effective personalized target therapy. The effects of VEGF receptors after ligand binding are mediated through receptor tyrosine autophosphorylation. We determined the relevance of the VEGFR-1 activating pathway for colon cancer (CC) metastasis.

Methods

The expression profiles of VEGFR-1, phosphorylated (activated) VEGFR-1 (pVEGFR-1^Tyr1048, pVEGFR-1^Tyr1213 and pVEGFR-1^Tyr1333) and the VEGFR-1 ligands (VEGF, PlGF and VEGF-B) were investigated using immunohistochemistry in different tumor compartments (intratumoral - invasive front - extratumoral), cell types (tumor cells – macro- (large and small vessels) and the microvasculature (capillaries) - inflammatory cells) in human sporadic non-metastatic, lymphogenous metastatic and haematogenous metastatic CC.

Results

VEGF and PlGF produced by tumor cells have an autocrine affinity for their receptor VEGFR-1. Subsequent PlGF-mediated receptor activation by autophosphorylation at Tyr1048 and Tyr1213 is a potential signaling pathway, which in turn seems to protect against distant metastasis and, in regions of tumor budding, additionally against lymph node metastasis. This autocrine link could be supported by possible formation of PlGF-VEGF heterodimers and PlGF-PlGF homodimers, which are known to have anti-metastatic properties. In contrast, in order to enhance their potential for distant metastasis tumor cells produce paracrine-acting VEGF-B. VEGFR-1 activation in tumor-associated macrovasculature but not capillaries appears to affect metastatic ability. Paracrine-mediated receptor autophosphorylation at Tyr1048 and Tyr1213 in small vessels located intratumorally and along the invasive front appears to be inversely correlated with metastasis, especially distant metastasis. Additionally, macrovessels are able to produce VEGFR-1 ligands, which influence the metastatic potential. Paracrine-acting VEGF-B production by intratumorally located small vessels and autocrine-acting PlGF production by extratumorally located small vessels seem to be associated with the non-metastatic phenotype. In contrast, VEGF-B-expressing extratumoral large and small vessels correlate with distant metastasis. Lymphocyte-associated VEGFR-1 expression in the invasive front without accompanying autophosphorylation could prevent against distant metastasis possibly by acting as a decoy and scavenger receptor.

Conclusion

VEGFR-1 and its ligands participate in vascular, tumor cell-mediated and immuno-inflammatory processes in a complex biomolecule-dependent and tumor zone-specific manner and hence could influence metastatic behavior in CC.

Leukocyte driven-decidual angiogenesis in early pregnancy

Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed.

The pathophysiology of retinopathy of prematurity: an update of previous and recent knowledge

Retinopathy of prematurity (ROP) is a disease that can cause blindness in very low birthweight infants. The incidence of ROP is closely correlated with the weight and the gestational age at birth. Despite current therapies, ROP continues to be a highly debilitating disease. Our advancing knowledge of the pathogenesis of ROP has encouraged investigations into new antivasculogenic therapies. The purpose of this article is to review the findings on the pathophysiological mechanisms that contribute to the transition between the first and second phases of ROP and to investigate new potential therapies. Oxygen has been well characterized for the key role that it plays in retinal neoangiogenesis. Low or high levels of pO2 regulate the normal or abnormal production of hypoxia-inducible factor 1 and vascular endothelial growth factors (VEGF), which are the predominant regulators of retinal angiogenesis. Although low oxygen saturation appears to reduce the risk of severe ROP when carefully controlled within the first few weeks of life, the optimal level of saturation still remains uncertain. IGF-1 and Epo are fundamentally required during both phases of ROP, as alterations in their protein levels can modulate disease progression. Therefore, rhIGF-1 and rhEpo were tested for their abilities to prevent the loss of vasculature during the first phase of ROP, whereas anti-VEGF drugs were tested during the second phase. At present, previous hypotheses concerning ROP should be amended with new pathogenetic theories. Studies on the role of genetic components, nitric oxide, adenosine, apelin and β-adrenergic receptor have revealed new possibilities for the treatment of ROP. The genetic hypothesis that single-nucleotide polymorphisms within the β-ARs play an active role in the pathogenesis of ROP suggests the concept of disease prevention using β-blockers. In conclusion, all factors that can mediate the progression from the avascular to the proliferative phase might have significant implications for the further understanding and treatment of ROP.

Vasculogenic cytokines in wound healing

Chronic wounds represent a growing healthcare burden that particularly afflicts aged, diabetic, vasculopathic, and obese patients. Studies have shown that nonhealing wounds are characterized by dysregulated cytokine networks that impair blood vessel formation. Two distinct forms of neovascularization have been described: vasculogenesis (driven by bone-marrow-derived circulating endothelial progenitor cells) and angiogenesis (local endothelial cell sprouting from existing vasculature). Researchers have traditionally focused on angiogenesis but defects in vasculogenesis are increasingly recognized to impact diseases including wound healing. A more comprehensive understanding of vasculogenic cytokine networks may facilitate the development of novel strategies to treat recalcitrant wounds. Further, the clinical success of endothelial progenitor cell-based therapies will depend not only on the delivery of the cells themselves but also on the appropriate cytokine milieu to promote tissue regeneration. This paper will highlight major cytokines involved in vasculogenesis within the context of cutaneous wound healing.

Chronic hypoxia and VEGF differentially modulate abundance and organization of myosin heavy chain isoforms in fetal and adult ovine arteries

Chronic hypoxia increases vascular endothelial growth factor (VEGF) and thereby promotes angiogenesis. The present study explores the hypothesis that hypoxic increases in VEGF also remodel artery wall structure and contractility through phenotypic transformation of smooth muscle. Pregnant and nonpregnant ewes were maintained at sea level (normoxia) or 3,820 m (hypoxia) for the final 110 days of gestation. Common carotid arteries harvested from term fetal lambs and nonpregnant adults were denuded of endothelium and studied in vitro. Stretch-dependent contractile stresses were 32 and 77% of normoxic values in hypoxic fetal and adult arteries. Hypoxic hypocontractility was coupled with increased abundance of nonmuscle myosin heavy chain (NM-MHC) in fetal (+37%) and adult (+119%) arteries. Conversely, hypoxia decreased smooth muscle MHC (SM-MHC) abundance by 40% in fetal arteries but increased it 123% in adult arteries. Hypoxia decreased colocalization of NM-MHC with smooth muscle α-actin (SM-αA) in fetal arteries and decreased colocalization of SM-MHC with SM-αA in adult arteries. Organ culture with physiological concentrations (3 ng/ml) of VEGF-A(165) similarly depressed stretch-dependent stresses to 37 and 49% of control fetal and adult values. The VEGF receptor antagonist vatalanib ablated VEGF's effects in adult but not fetal arteries, suggesting age-dependent VEGF receptor signaling. VEGF replicated hypoxic decreases in colocalization of NM-MHC with SM-αA in fetal arteries and decreases in colocalization of SM-MHC with SM-αA in adult arteries. These results suggest that hypoxic increases in VEGF not only promote angiogenesis but may also help mediate hypoxic arterial remodeling through age-dependent changes in smooth muscle phenotype and contractility.

Betaine inhibits in vitro and in vivo angiogenesis through suppression of the NF-κB and Akt signaling pathways

Angiogenesis is defined as the formation of new blood vessels form existing vessels surrounding a tumor. The process of angiogenesis is an important step for tumor growth and metastasis, as is inflammation. Thus, angiogenesis inhibitors that suppress inflammation have been studied as an anticancer treatment. Recently, many research groups have investigated the anti-angiogenic activity of natural compounds since some have been demonstrated to have anticancer properties. Among many natural compounds, we focused on betaine, which is known to suppress inflammation. Betaine, trimethylglycine (TMG), was first discovered in the juice of sugar beets and was later shown to be present in wheat, shellfish and spinach. In Southeast Asia, betaine is used in traditional oriental medicine for the treatment of hepatic disorders. Here, we report the anti-angiogenic action of betaine. Betaine inhibited in vitro angiogenic cascade, tube formation, migration and invasion of human umbilical vein endothelial cells (HUVECs). Betaine also inhibited in vivo angiogenesis in the mouse Matrigel plug assay. The mRNA expression levels of basic fibroblast growth factor (bFGF), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in HUVECs were decreased by betaine treatment. In addition, betaine suppressed NF-κB and Akt activation.

Improvement of cardiac function in the failing rat heart after transfer of skeletal myoblasts engineered to overexpress placental growth factor

BACKGROUND

Transplant of skeletal myoblasts is an attractive alternative to repair irreversibly damaged myocardium in ischemic heart failure. We investigated whether transplant of myoblasts overexpressing placental growth factor would stimulate angiogenesis and enhance myoblast survival in a rat heart failure model.

METHODS

Three weeks after myocardial infarction, Sprague-Dawley rats in heart failure received intramyocardial injections of Ringer solution (control) or autologous myoblasts, unmodified or transfected with placental growth factor expression plasmid. Sham-operated animals served as noninfarct controls. Cardiac function was assessed by echocardiography to 86 days after engraftment. Immunocytochemistry and fluorescence imaging were used to investigate vessel formation, grafted myoblast survival, infarct wall thickness, and infarct size. Quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting measured tissue messenger RNA and protein expressions.

RESULTS

Left ventricular function significantly improved with time, and fractional shortening on day 86 was significantly enhanced in transfected myoblast group relative to control (P < .01) and unmodified myoblast (P < .05) groups. Vascular density (P < .01) and myoblast survival (P < .05) were enhanced in rats treated with transfected myoblasts relative to other groups (P < .05). Mean fraction of fibrotic scar tissue was decreased in unmodified and transfected myoblast groups relative to controls on day 86 (P < .05), and left ventricular wall thickness was significantly increased in transfected myoblast group relative to other groups (P < .05).

CONCLUSIONS

Intramyocardial injections of autologous myoblasts overexpressing placental growth factor improved cardiac function, attenuated adverse cardiac remodeling, induced angiogenesis, and probably enhanced survival of grafted myoblasts.

Abnormal placentation, angiogenic factors, and the pathogenesis of preeclampsia

Preeclampsia is a common complication of pregnancy with potentially devastating consequences to both the mother and the baby.It is the leading cause of maternal deaths in developing countries. In developed countries it is the major cause of iatrogenic premature delivery and contributes significantly to increasing health care cost associated with prematurity. There is currently no known treatment for preeclampsia; ultimate treatment involves delivery of the placenta. Although there are several risk factors (such as multiple gestation or chronic hypertension), most patients present with no obvious risk factors. The molecular pathogenesis of preeclampsia is just now being elucidated. It has been proposed that abnormal placentation and an imbalance in angiogenic factors lead to the clinical findings and complications seen in preeclampsia. Preeclampsia is characterized by high levels of circulating antiangiogenic factors such as soluble fms-like tyrosine kinase-1 and soluble endoglin, which induce maternal endothelial dysfunction. These soluble factors are altered not only at the time of clinical disease but also several weeks before the onset of clinical signs and symptoms. Many methods of prediction and surveillance have been proposed to identify women who will develop preeclampsia, but studies have been inconclusive. With the recent discovery of the role of angiogenic factors in preeclampsia, novel methods of prediction and diagnosis are being developed to aid obstetricians and midwives in clinical practice. This article discusses the role of angiogenic factors in the pathogenesis, prediction, diagnosis, and possible treatment of preeclampsia.