From the cradle to the clinic: VEGF in developmental, physiological, and pathological angiogenesis

Determination of Urine Protein Levels and Analysis of Differences in Vascular Endothelial Growth Factor Levels between Early Onset and Late Onset Preeclampsia

BACKGROUND: Preeclampsia is a disease with the high mortality rate. Data indicate that 23.5% of maternal deaths due to preeclampsia. Urine protein testing is essential for pregnant women to discover the function of kidney during pregnancy and to identify the presence of preeclampsia, both mild and severe, which it can lead to eclampsia. Preeclampsia based on onset can also be detected by examining serum biomarkers of Vascular Endothelial Growth Factor (VEGF). AIM: The aim of this study was to overview the urine protein levels and analyzed the differences serum VEGF levels between the early and late onset of preeclampsia. MATERIALS AND METHODS: This study used design of the cross sectional comparative study in RSUP DR. M Djamil Padang, Pariaman Hospital, Aisiyah Pariaman Hospital, and Padang Pariaman Regional Hospital for 2 years. The population in this study consisted of patients with early and late onset preeclampsia who went to the study site during that time and met the inclusion criteria. Sampling with consecutive sampling consisted of 28 people per group. RESULTS: The results revealed that the number of patients who had urine protein levels with a value of 2+ at the early onset was 14 and at the late onset was 12, meanwhile for patients with a urine protein content value of 3+ at the early onset it was 14 and at the late onset was 10.For the category urine protein with a value of 4+ amounted to 6 people only in the late onset group. The results of the normality test showed that the mean value of VEGF levels at early onset and late onset was 3.91 pg / ml and 4.3 pg / ml, respectively. Thus, the level of VEGF serum had an abnormal distribution and it led to the T test data could not be tested. So then, the testing was done using a non-parametric test, namely the Mann-Whittney test. The mean levels of VEGF, respectively, based on the Mann-Whittney test for early onset preeclampsia and late onset preeclampsia were 29.75 ng / mL and 30.25 ng / mL. VEGF in early onset preeclampsia is lower than late onset preeclampsia. CONCLUSION: Based on the results obtained, it can be concluded that there was no significant difference in the level of VEGF in early onset preeclampsia and late onset preeclampsia (p = 0.42). Keywords: Preeclampsia, early onset, late onset, urine protein, VEGF

Peripheral vascular disease: preclinical models and emerging therapeutic targeting of the vascular endothelial growth factor ligand-receptor system

Introduction: Vascular endothelial growth factor (VEGF)-A is a sought therapeutic target for PAD treatment because of its potent role in angiogenesis. However, no therapeutic benefit was achieved in VEGF-A clinical trials, suggesting that our understanding of VEGF-A biology and ischemic angiogenic processes needs development. Alternate splicing in VEGF-A produces pro- and anti-angiogenic VEGF-A isoforms; the only difference being a 6-amino acid switch in the C-terminus of the final 8th exon of the gene. This finding has changed our understanding of VEGF-A biology and may explain the lack of benefit in VEGF-A clinical trials. It presents new therapeutic opportunities for peripheral arterial disease (PAD) treatment.Areas covered: Literature search was conducted to include: 1) predicted mechanism by which the anti-angiogenic VEGF-A isoform would inhibit angiogenesis, 2) unexpected mechanism of action, and 3) how this mechanism revealed novel signaling pathways that may enhance future therapeutics in PAD.Expert opinion: Inhibiting a specific anti-angiogenic VEGF-A isoform in ischemic muscle promotes perfusion recovery in preclinical PAD. Additional efforts focused on the production of these isoforms, and the pathways altered by modulating different VEGF receptor-ligand interactions, and how this new data may allow bedside progress offers new approaches to PAD are discussed.I.

TIMP3/TGF‑β1 axis regulates mechanical loading‑induced chondrocyte degeneration and angiogenesis

Chondrocytes in injured cartilage tissue are susceptible to mechanical loading; mechanical overloading can induce cartilage degeneration. The aim of the present study was to investigate whether mechanical loading can regulate chondrocyte degeneration and angiogenesis via the tissue inhibitor of matrix metalloproteinase-3 (TIMP3)/transforming growth factor (TGF)-β1 axis. Primary human chondrocytes were obtained from knee articular cartilage of a healthy donor. Then, normal chondrocytes or TIMP3 lentivirus-transfected (LV-TIMP3) chondrocytes were subjected to mechanical loading (10 MPa compression). Then, chondrocytes were stimulated with 1 µg/ml lipopolysaccharide (LPS) or treated with LDN-193189 (inhibitor of TGF-β1 signaling pathway). In addition, human umbilical vein endothelial cells (HUVECs) were co-cultured with chondrocytes or LV-TIMP3 chondrocytes. The expression levels of collagen-I, proteoglycan, TIMP3, TGF-β1, Smad2 and Smad3 were detected by reverse transcription-quantitative PCR and western blotting. Moreover, cell apoptosis and viability were determined using flow cytometry and MTT analysis, while cell migration was observed by Transwell assays. In addition, the vascular endothelial growth factor (VEGF)/VEGF receptor (R)2 binding rate in HUVECs was detected by a solid-phase binding assay. It was demonstrated that mechanical loading significantly inhibited the expression levels of collagen-I and proteoglycan in chondrocytes, as well as reducing cell proliferation and promoting cell apoptosis. In addition, the expression levels of TIMP3, TGF-β1, phosphorylated (p)-Smad2 and p-Smad3 were significantly decreased in degenerated chondrocytes that were induced by LPS, as well as in chondrocytes treated with LDN-193189. Furthermore, TIMP3 overexpression suppressed cell migration and reduced the VEGF/VEGFR2 binding rate in HUVECs. Mechanical loading significantly inhibited the expression levels of TIMP3, TGF-β1, p-Smad2 and p-Smad3 in chondrocytes, and also increased cell migration of HUVECs; TGF-β1 treatment or TIMP3 overexpression reversed these effects. Thus, the TIMP3/TGF-β1 axis may be a vital signaling pathway in mechanical loading-induced chondrocyte degeneration and angiogenesis.

Enhanced thrombospondin-1 causes dysfunction of vascular endothelial cells derived from Fabry disease-induced pluripotent stem cells

BACKGROUND

Fabry disease (FD) is a recessive X-linked lysosomal storage disorder caused by α-galactosidase A (GLA) deficiency. Although the mechanism is unclear, GLA deficiency causes an accumulation of globotriaosylceramide (Gb3), leading to vasculopathy.

METHODS

To explore the relationship between the accumulation of Gb3 and vasculopathy, induced pluripotent stem cells generated from four Fabry patients (FD-iPSCs) were differentiated into vascular endothelial cells (VECs). Genome editing using CRISPR-Cas9 system was carried out to correct the GLA mutation or to delete Thrombospondin-1 (TSP-1). Global transcriptomes were compared between wild-type (WT)- and FD-VECs by RNA-sequencing analysis.

FINDINGS

Here, we report that overexpression of TSP-1 contributes to the dysfunction of VECs in FD. VECs originating from FD-iPSCs (FD-VECs) showed aberrant angiogenic functionality even upon treatment with recombinant α-galactosidase. Intriguingly, FD-VECs produced more p-SMAD2 and TSP-1 than WT-VECs. We also found elevated TSP-1 in the peritubular capillaries of renal tissues biopsied from FD patients. Inhibition of SMAD2 signaling or knock out of TSP-1 (TSP-1-/-) rescues normal vascular functionality in FD-VECs, like in gene-corrected FD-VECs. In addition, the enhanced oxygen consumption rate is reduced in TSP-1-/- FD-VECs.

INTERPRETATION

The overexpression of TSP-1 secondary to Gb3 accumulation is primarily responsible for the observed FD-VEC dysfunction. Our findings implicate dysfunctional VEC angiogenesis in the peritubular capillaries in some of the complications of Fabry disease.

FUNDING

This study was supported by grant 2018M3A9H1078330 from the National Research Foundation of the Republic of Korea.

Ocular Inflammation in Cynomolgus Macaques Following Intravenous Administration of a Human Monoclonal Antibody

Angiogenesis is a major component of the pathogenesis of various ocular diseases, including age-related macular degeneration (AMD). CNTO95 is a fully human monoclonal antibody against αν integrins that has shown antiangiogenic properties in cynomolgus macaques and rats. Because angiogenesis inhibitors may have the potential to treat AMD, a proof-of-concept study was conducted in a macaque model of laser-induced choroidal neovascularization. In the course of this study, transient, intense anterior chamber ocular inflammation was observed within 24 hours following the first intravitreal or intravenous administration of the human monoclonal antibody. These animals had no outward signs of ocular toxicity or discomfort. Additional ocular safety studies demonstrated that the inflammation following intravenous administration of CNTO95 was not due to a contaminant in the vehicle, not due to endotoxin, and not a nonspecific reaction in the macaques from administration of a human monoclonal antibody. The anterior chamber ocular inflammation noted following the first dose did not recur with subsequent CNTO95 dosing. In repeated-dose toxicology studies, histopathological examination of the eyes revealed no ocular toxicity. The reason for the ocular inflammation following intravenous dosing remains unresolved but may be a secondary manifestation of a first-dose systemic infusion reaction.

Targeting vascular endothelial growth factor ameliorates PMMA-particles induced inflammatory osteolysis in murine calvaria

Cytokines and growth factors mediate inflammatory osteolysis in response to particles released from bone implants. However, the mechanism by which this process develops is not entirely clear. Blood vessels and related factors may be required to deliver immune cells and soluble factors to the injury site. Therefore, in the current study we investigated if, vascular endothelial growth factor (VEGF), which is required for angiogenesis, mediates polymethylmethacrylate (PMMA) particles-induced osteolysis. Using bone marrow derived macrophages (BMMs) and ST2 stromal cell line, we show that PMMA particles increase VEGF expression. Further, using a murine calvarial osteolysis model, we found that PMMA injection over calvaria induce significant increase in VEGF expression as well as new vessel formation, represented by von Willebrand factor (vWF) staining. Co-treatment using a VEGF-neutralizing antibody abrogated expression of vWF, indicating decreased angiogenesis. Finally, VEGF neutralizing antibody reduced expression of Tumor necrosis factor (TNF) and decreased osteoclastogenesis induced by PMMA particles in calvariae. This work highlights the significance of angiogenesis, specifically VEGF, as key driver of PMMA particle-induced inflammatory osteolysis, inhibition of which attenuates this response.

Tendon healing in the context of complex fractures

Tendons connect muscle to bone and play an integral role in bone and joint alignment and loading. Tendons act as pulleys that provide anchorage of muscle forces for joint motion and stability, as well as for fracture reduction and realignment. Patients that experience complex fractures also have concomitant soft tissue injuries, such as tendon damage or rupture. Tendon injuries that occur at the time of bone fracture have long-term ramifications on musculoskeletal health, yet these injuries are often disregarded in clinical treatment and diagnosis for patients with bone fractures as well as in basic science approaches for understanding bone repair processes. Delayed assessment of soft tissue injuries during evaluation of trauma can lead to chronic pain, dysfunction, and delayed bone healing even following successful fracture repair, highlighting the importance of identifying and treating damaged tendons early. Treatment strategies for bone repair, such as mechanical stabilization and biological therapeutics, can impact tendon healing and function. Because poor tendon healing following complex fracture can significantly impact the function of tendon during bone fracture healing, a need exists to understand the healing process of complex fractures more broadly, beyond the healing of bone. In this review, we explored the mechanical and biological interaction of bone and tendon in the context of complex fracture, as well as the relevance and potential ramifications of tendon damage following bone fracture, which has particular impact on patients that experience complex fractures, such as from combat, automobile accidents, and other trauma.

A novel mutation in the conserved sequence of vascular endothelial growth factor receptor 3 leads to primary lymphoedema

Objective

To investigate whether lymphoedema in a Chinese family showed the hereditary and clinical characteristics of Milroy disease, an autosomal dominant form of congenital lymphoedema, typically characterized by chronic lower limb tissue swelling due to abnormal lymphatic vasculature development, and to perform mutational analyses of vascular endothelial growth factor receptor (VEGFR)3.

Methods

Individuals from a three-generation family affected by congenital lymphoedema were clinically assessed for Milroy disease. Mutation analysis of VEGFR3 was performed using DNA from family members and healthy controls.

Results

Out of 20 family members, eight were diagnosed with hereditary lymphoedema. Mutation analyses revealed a novel mutation site for c.3163 G>A, resulting in a p.1055D>N mutation in the second tyrosine kinase domain of VEGFR3, which was present in affected individuals only (absent in all unaffected family members and 130 healthy controls). Computed functional analyses showed the mutation may lead to structural alterations with a probability of 0.99999 of being disease causing.

Conclusion

A novel mutation associated with Milroy disease was identified in a Chinese family, expanding our knowledge of VEGFR3 gene function and providing a potential molecular target for treating hereditary lymphoedema.

A Molecular and Clinical Review of Stem Cell Therapy in Critical Limb Ischemia

Peripheral artery disease (PAD) is one of the major vascular complications in individuals suffering from diabetes and in the elderly that can progress to critical limb ischemia (CLI), portending significant burden in terms of patient morbidity and mortality. Over the last two decades, stem cell therapy (SCT) has risen as an attractive alternative to traditional surgical and/or endovascular revascularization to treat this disorder. The primary benefit of SCT is to induce therapeutic neovascularization and promote collateral vessel formation to increase blood flow in the ischemic limb and soft tissue. Existing evidence provides a solid rationale for ongoing in-depth studies aimed at advancing current SCT that may change the way PAD/CLI patients are treated.

Roles of VEGF-Flt-1 signaling in malignant behaviors of oral squamous cell carcinoma

Background

Vascular endothelial growth factor (VEGF) is a highly specific signaling protein for vascular endothelial cells that plays a critical role in tumor growth and invasion through angiogenesis, and may contribute to cell migration and activation of pre-osteoclasts, osteoclasts and some tumor cells.

Objectives

We aimed to clarify the detailed roles of VEGF-Flt-1 signaling in bone invasion of oral squamous cell carcinoma (OSCC) cells.

Results

Forty-two (42) of 54 cases with gingival SCC (77.8%) strongly expressed VEGF, and had a significantly increased number of Flt-1+ osteoclasts (p<0.01) and more aggressive bone invasion (p<0.05). PlGF, a ligand of Flt-1, induced osteoclastogenesis in single culture of bone marrow cells (BMCs), and inhibition of Flt-1-signaling by VEGF tyrosine kinase inhibitor and It’s down stream (Akt and ERK1/2) inhibitos reduced osteoclastogenesis in PlGF-stimulated BMCs (p<0.01). In molecular level, PlGF stimulation significantly upregulated RANKL expression in Flt-1-expressing HSC2 cells via phosphorylation of Akt and ERK1/2. In the co-culture of VEGF-producing HSC2 cells and BMCs, number of TRAP-positive osteoclasts markedly increased (p<0.01). The osteoclastogenesis was significantly inhibited by RANKL-neutralizing antibody (p<0.01) as well as by VEGF tyrosine kinase inhibitor (p<0.01) and it’s downstream (Akt and ERK1/2) inhibitors (p<0.01, p<0.05, respectively).

Conclusion

VEGF-Flt-1 signaling induces osteoclastogenesis in OSCC through two possible ways: 1) VEGF produced from OSCC cells can directly stimulate the Flt-1 pathway in preosteoclasts to induce migration to future bone resorbing area and differentiation into osteoclasts, and 2) VEGF-Flt-1 signaling upregulates RANKL expression in OSCC cells, which indirectly leads to osteoclast differentiation. Therefore, blocking of the VEGF-Flt-1 signaling may help inhibit bone invasion of OSCC.

The role of mechano-growth factor E peptide in the regulation of osteosarcoma

Osteosarcoma is one of the most common bone tumors, and exhibits a high degree of malignancy. Gene therapy is a novel approach to its treatment, however, specific target genes are required to enable effective use of this therapy. In order to investigate the effects of the mechano-growth factor E (MGF-E) peptide, which is derived from the IGF-I alternative splicing isoform, on the regulation of the development of osteosarcoma, the expression of MGF was detected in osteosarcoma cell lines with different degrees of malignancy. Concomitantly, exogenous MGF-E peptide was used to stimulate these osteosarcoma cell lines. The results demonstrated that MGF was overexpressed in malignant osteosarcoma cells, while it was not expressed in the least malignant osteosarcoma cells. Furthermore, MGF-E treatment altered the cell cycle distribution, and promoted the proliferation, migration and invasion of osteosarcoma cells. The possible mechanisms underlying these effects were detected by quantitative polymerase chain reaction and western blotting. Based on these results, it was hypothesized that MGF may be a suitable biomarker for malignant osteosarcoma phenotypes.

Effect of soft-tissue attachment on tibial fracture healing in rats

PURPOSE

To compare tibial fracture healing in rats with or without soft-tissue attachment.

METHODS

The left tibias of 30 Wistar rats were osteotomised and equally randomised into 3 groups. In the avascular segmental fracture group, an 8-mm bone segment were first removed and then immediately put back. In the vascular segmental fracture group, the 8-mm bone segment was not displaced, with periosteal and muscular attachments. In the simple fracture group, a simple fracture in the middle tibia was made. All tibias were then stabilised with an intramedullary nail through the patellar tendon, and the wound was closed with sutures. After 8 weeks, all left tibias and 9 of the intact right tibias were harvested. Bone mineral content and density of the calluses were assessed using dual energy X-ray absorptiometry scanning. The maximum torsional strength, rigidity, and energy to failure of the tibias were measured.

RESULTS

All tibias healed (callus formation), without mal-union or pin migration. The 3 groups did not differ significantly in terms of torsional strength, rigidity, energy to failure, bone mineral content, and bone mineral density. The mean torsional strength of the 9 intact tibias was significantly higher than the healed tibias (14.9 vs. 10.6 Nmm, p=0.021).

CONCLUSION

Soft-tissue detachment from bone segments did not impair bone healing in rats.

Discovering up-regulated VEGF-C expression in swine umbilical vein endothelial cells by classical swine fever virus Shimen

Infection of domestic swine with the highly virulent Shimen strain of classical swine fever virus causes hemorrhagic lymphadenitis and diffuse hemorrhaging in infected swine. We analyzed patterns of gene expression for CSFV Shimen in swine umbilical vein endothelial cells (SUVECs). Transcription of the vascular endothelial growth factor (VEGF) C gene (VEGF-C) and translation of the corresponding protein were significantly up-regulated in SUVECs. Our findings suggest that VEGF-C is involved in mechanisms of acute infection caused by virulent strains of CSFV.

Increased vascularization during early healing after biologic augmentation in repair of chronic rotator cuff tears using autologous leukocyte- and platelet-rich fibrin (L-PRF): a prospective randomized controlled pilot trial

HYPOTHESIS

We hypothesized that arthroscopic rotator cuff repairs using leukocyte- and platelet-rich fibrin (L-PRF) in a standardized, modified protocol is technically feasible and results in a higher vascularization response and watertight healing rate during early healing.

METHODS

Twenty patients with chronic rotator cuff tears were randomly assigned to 2 treatment groups. In the test group (N = 10), L-PRF was added in between the tendon and the bone during arthroscopic rotator cuff repair. The second group served as control (N = 10). They received the same arthroscopic treatment without the use of L-PRF. We used a double-row tension band technique. Clinical examinations including subjective shoulder value, visual analog scale, Constant, and Simple Shoulder Test scores and measurement of the vascularization with power Doppler ultrasonography were made at 6 and 12 weeks.

RESULTS

There have been no postoperative complications. At 6 and 12 weeks, there was no significant difference in the clinical scores between the test and the control groups. The mean vascularization index of the surgical tendon-to-bone insertions was always significantly higher in the L-PRF group than in the contralateral healthy shoulders at 6 and 12 weeks (P = .0001). Whereas the L-PRF group showed a higher vascularization compared with the control group at 6 weeks (P = .001), there was no difference after 12 weeks of follow-up (P = .889). Watertight healing was obtained in 89% of the repaired cuffs.

DISCUSSION/CONCLUSIONS

Arthroscopic rotator cuff repair with the application of L-PRF is technically feasible and yields higher early vascularization. Increased vascularization may potentially predispose to an increased and earlier cellular response and an increased healing rate.

Extracellular matrix degradation and tissue remodeling in periprosthetic loosening and osteolysis: focus on matrix metalloproteinases, their endogenous tissue inhibitors, and the proteasome

The leading complication of total joint replacement is periprosthetic osteolysis, which often results in aseptic loosening of the implant, leading to revision surgery. Extracellular matrix degradation and connective tissue remodeling around implants have been considered as major biological events in the periprosthetic loosening. Critical mediators of wear particle-induced inflammatory osteolysis released by periprosthetic synovial cells (mainly macrophages) are inflammatory cytokines, chemokines, and proteolytic enzymes, mainly matrix metalloproteinases (MMPs). Numerous studies reveal a strong interdependence of MMP expression and activity with the molecular mechanisms that control the composition and turnover of periprosthetic matrices. MMPs can either actively modulate or be modulated by the molecular mechanisms that determine the debris-induced remodeling of the periprosthetic microenvironment. In the present study, the molecular mechanisms that control the composition, turnover, and activity of matrix macromolecules within the periprosthetic microenvironment exposed to wear debris are summarized and presented. Special emphasis is given to MMPs and their endogenous tissue inhibitors (TIMPs), as well as to the proteasome pathway, which appears to be an elegant molecular regulator of specific matrix macromolecules (including specific MMPs and TIMPs). Furthermore, strong rationale for potential clinical applications of the described molecular mechanisms to the treatment of periprosthetic loosening and osteolysis is provided.

Vascular endothelial growth factor gene 1154 G/A, 2578 C/A, 460 C/T, 936 C/T polymorphisms and association with recurrent pregnancy losses

Vascular endothelial growth factor (VEGF) regulates endothelial cell proliferation, migration and differentiation. VEGF plays a critical role in angiogenesis during placenta formation. We investigated whether VEGF gene polymorphisms are associated with recurrent pregnancy loss. Thirty-eight women with recurrent pregnancy loss and 30 control women with live-born children were recruited from 2010 to 2011 in the region of Bursa, Turkey. VEGF gene polymorphisms were assessed with PCR-RFLP analysis of DNA samples obtained from leukocytes. DNA fragments were investigated by using appropriate primers. SNP scanning was performed using MnII, BgIII, BshI2361, Hsp92II restriction enzymes for 1154 G/A, 2578 C/A, 460 C/T, and 936 C/T polymorphisms, respectively. The frequencies of 2578 C/A, 460 C/T, 936 C/T polymorphisms were not significantly different between the controls and women with recurrent pregnancy loss. However, the prevalence of the 1154 G/A polymorphism A/A genotype was significantly higher in the recurrent pregnancy loss group (23.7 vs 3.4%). One of the four common polymorphisms of the VEGF gene was found to be more frequent in women with recurrent pregnancy loss. It is possible that disruption of VEGF function and placental angiogenesis can contribute to pregnancy loss in women with recurrent pregnancy loss.

The role of VEGF and KDR polymorphisms in moyamoya disease and collateral revascularization

We conducted a case-control study to investigate whether vascular endothelial growth factor (VEGF −2578, −1154, −634, and 936) and kinase insert domain containing receptor (KDR −604, 1192, and 1719) polymorphisms are associated with moyamoya disease. Korean patients with moyamoya disease (n = 107, mean age, 20.9±15.9 years; 66.4% female) and 243 healthy control subjects (mean age, 23.0±16.1 years; 56.8% female) were included. The subjects were divided into pediatric and adult groups. Among the 64 surgical patients, we evaluated collateral vessel formation after 2 years and divided patients into good (collateral grade A) or poor (collateral grade B and C) groups. The frequencies and distributions of four VEGF (−2578, −1154, −634, and 936) and KDR (−604, 1192, and 1719) polymorphisms were assessed from patients with moyamoya disease and compared to the control group. No differences were observed in VEGF −2578, −1154, −634, and 936 or KDR −604, 1192, and 1719 polymorphisms between the control group and moyamoya disease group. However, we found the −634CC genotype occurred less frequently in the pediatric moyamoya group (p = 0.040) whereas the KDR −604C/1192A/1719T haplotype increased the risk of pediatric moyamoya (p = 0.024). Patients with the CC genotype of VEGF −634 had better collateral vessel formation after surgery. Our results suggest that the VEGF −634G allele is associated with pediatric moyamoya disease and poor collateral vessel formation.

Vascular endothelial growth factor gene polymorphisms in spontaneously aborted fetuses

PROBLEMS

The VEGF-1154G>A polymorphism has been reported to be a genetic risk factor for recurrent spontaneous abortion in various studies; however, these studies have focused on genetic analyses of pregnant women rather than aborted fetuses. To evaluate and confirm the association between the VEGF-1154G>A polymorphism and spontaneous abortion, we focused on the relationship between four polymorphisms in the VEGF gene (-2578C>A, -1154G>A, -634G>C, and 936C>T) and spontaneously aborted fetuses (SAFs).

METHOD OF STUDY

The subjects included 118 SAFs at <20 weeks gestation and 380 normal controls consisting of children and adults. The polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Spontaneously aborted fetuses exhibited significantly different frequencies of the -2578CA+AA/-634CC and -1154GA+AA/-634CC combined genotypes compared with control subjects. The frequency of the -2578A/-1154A/-634C/936C haplotype was significantly higher in SAFs.

CONCLUSIONS

VEGF genes -2578CA+AA/-634CC and -1154GA+AA/-634CC in the fetus are possible risk factors for spontaneous abortion.

Vascular endothelial growth factor gene polymorphisms in Korean patients with premature ovarian failure

OBJECTIVE

To study the association of vascular endothelial growth factor (VEGF) polymorphisms (-2578C>A, -1154G>A, -634G>C, and 936C>T) with premature ovarian failure (POF) in Korean patients.

STUDY DESIGN

Prospective case-control study. One hundred and thirty five patients with POF and confirmed serum follicle-stimulating hormone levels of >40IU/L before the age of 40 years and 120 healthy controls with at least one live birth, regular menstrual cycles, and karyotype 46, XX.

RESULTS

POF patients exhibited significantly different frequencies of the VEGF -1154GA genotype (odds ratio [OR], 2.002; 95% confidence interval [CI], 1.116-3.592; P=0.019), and -2578CA+AA/-1154GA+AA combination genotype (OR, 1.805; 95% CI, 1.013-3.217; P=0.044) compared to the control group. The frequency of the -2578A/-1154A haplotype (OR, 1.647; 95% CI, 1.017-2.677; P=0.041) was significantly higher in the POF group than in the control group.

CONCLUSION

The VEGF -1154G>A mutation, -2578CA+AA/-1154GA+AA combination genotype, and -2578A/-1154A haplotype are significantly associated with POF in Korean women.

Immunohistochemical study of angiogenesis and angiogenic factors in equine granulosa cell tumours

The first part of our study (Müller et al., 2009) characterized angiogenesis in the equine cycling ovary through histomorphological and immunohistochemical examinations (vascular endothelial growth factors A and B [VEGF A, VEGF B], vascular endothelial growth factor receptors 1 and 2 [VEGF-R1, VEGF-R2], vascular angiopoietins 1 and 2 [Ang1, Ang2], angiopoietin receptor [Tie2], and von Willebrand Factor). Since angiogenesis plays an important role in development and growth of numerous tumours, the second part of our study involved a similar examination of 70 equine granulosa cell tumours (GCTt). The results of the second study were compared with those of the normal equine ovary. Certain similarities in the expression pattern could be detected between normal, cyclical ovaries (Müller et al., 2009) and GCTt. The immunoreactivity of granulosa cells and Leydig-like cells in GCTt resembles granulosa cells and luteinized thecal cells in periovulatory cycling ovaries. The neoplastic cells support circulation, supply and growth of GCTt by contributing to angiogenesis.

Effects of SU5416 and a vascular endothelial growth factor neutralizing antibody on wear debris-induced inflammatory osteolysis in a mouse model

Background

The development of highly vascularized and inflammatory periprosthetic tissue characterizes the progress of aseptic loosening, a major complication of joint arthroplasty. Vascular endothelial growth factor (VEGF) is an important cell signaling protein involved in angiogenesis. The purpose of this study was to investigate whether R2/Fc (a VEGF neutralizing antibody) and SU5416 (a VEGF receptor II [Flk-1] inhibitor) could ameliorate particle-induced inflammatory osteolysis in a mouse model.

Methods

Ultrahigh molecular weight polyethylene (UHMWPE) particles were introduced into established air pouches in BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. Drug treatment was started 2 weeks after bone implantation, and mice without drug treatment were included as controls. Pouch tissues were harvested 4 weeks after bone implantation for molecular and histological analysis, and implanted bone degradation was analyzed by microcomputed tomography.

Results

Exposure to UHMWPE particles induced inflammatory osteolysis, which was associated with increased expression of VEGF/Flt-1 proteins. Treatment with R2/Fc significantly improved UHMWPE particle-induced inflammatory osteolysis, and reduced the expression of VEGF/Flt-1 proteins. However, SU5416 treatment showed no effect on UHMWPE particle-induced inflammatory osteolysis.

Conclusion

Our findings indicate that VEGF signaling exerts a regulatory effect on the development of UHMWPE-induced inflammatory osteolysis, through its unique Flt-1, rather than Flk-1, receptor located on monocyte/macrophage cell lineages. These data provide a biological rationale for a VEGF/Flt-1-targeted treatment strategy, especially during the early stages of the wear debris-induced inflammatory response.

Comparison of the vascularity of fasciocutaneous tissue and muscle for coverage of open tibial fractures

BACKGROUND

Early coverage with vascularized soft-tissue flaps has dramatically improved the outcome in open tibial fractures. However, the ideal tissue for covering open fractures remains controversial. Several clinical studies suggest that muscle is superior to fasciocutaneous tissue; this is attributed to the presumed higher vascularity of muscle, although experimental evidence is inconclusive. The authors' previously described novel murine fracture model, which allows exclusive comparison of both tissues, demonstrated enhanced healing beneath muscle. The present study was undertaken to compare the vascularity of muscle and fasciocutaneous tissues over the course of fracture healing.

METHODS

Two experimental groups comprised mice with tibial fractures in contact with either muscle or fasciocutaneous tissues exclusively. Controls included a nontrauma group and those where soft tissues and periosteum were dissected but the tibia was not fractured. Animals were harvested between 3 and 28 days after fracture (n = 170 in total). The vascular density of the soft tissues was assessed using immunohistochemical techniques.

RESULTS

Fasciocutaneous tissue was found to have a higher vascular density compared with muscle in contact with the fracture site at all time points (p < 0.0001, two-way analysis of variance), despite accelerated healing of fractures covered by muscle.

CONCLUSIONS

The authors' data show that the more advanced healing of fractures covered by muscle compared with fasciocutaneous tissue is not related to the vascularity of the tissues, as the latter had a higher vascular density at all time points. Therefore, provided that a flap has sufficient vascularity to effectively reconstitute the soft-tissue envelope, other factors may be important in specifically promoting fracture healing.

Vascular endothelial growth factor gene polymorphisms and pregnancy

Vascular endothelial growth factor (VEGF) is a major angiogenic factor and prime regulator of endothelial cell proliferation. During pregnancy, VEGF is essential for the proliferation of trophoblasts, the development of embryonic vasculature and the growth of maternal and fetal blood cells in utero. In cases of pre-eclampsia and in some circumstances of preterm labor-raised umbilical cord serum, VEGF levels might be correlated with the clinical development of the above pathological disorders. Genetic alteration as 936C/T VEGF gene polymorphism has a statistical significant correlation with the severity of pre-eclampsia. The same VEGF gene polymorphism, which has been associated with lower protein production, has an increased risk of spontaneous preterm delivery in a Greek-studied population. Homozygotes were found to carry the greatest risk with a lesser proportionate risk associated with heterozygosity, whereas women with the -1154 allele of the VEGF gene have an increased risk of recurrent pregnancy loss. In this review, we present evidence that demonstrates an implication of VEGF gene polymorphisms in the pathological disorders of pregnancy. However, further genetic studies are needed to confirm these data.

Characterization of vascular endothelial growth factor receptors on the endothelial cell surface during hypoxia using whole cell binding arrays

Angiogenesis plays a central role in a variety of important biological processes such as reproduction, tissue development, and wound healing, as well as being critical to tumor formation in cancer. The development of chromosomal substitution (consomic) rat strains has permitted the chromosomal localization of genetic factors critical to angiogenesis, but many questions remain as to the mechanisms involved. Here we utilize a novel cell capture assay to assess changes in the functional expression of vascular endothelial growth factor (VEGF) receptors on the surface of vascular endothelial cells isolated from rat strains that are normal or impaired in angiogenesis. We show that functional VEGF receptor expression is increased under hypoxic conditions in rat strains that exhibit normal angiogenesis but not in a strain impaired in angiogenesis. This result implicates the dysregulation of VEGF receptor expression levels on the endothelial cell surface as a key factor in impaired angiogenesis.

Decreased endothelial progenitor cells in umbilical cord blood in severe preeclampsia

BACKGROUND/AIMS

We compared the numbers of endothelial progenitor cells (EPCs) in umbilical cord blood in severe preeclampsia and normal pregnancy, along with the cord blood plasma levels of free VEGF and sVEGFR-1.

METHODS

Umbilical cord blood EPC counts in severe preeclampsia (n = 15) and gestationally matched normal pregnant women (n = 30) were retrospectively analyzed. Cord plasma free VEGF and sVEGFR-1 levels were measured by enzyme immunoassay.

RESULTS

Significantly higher systolic blood pressure, lower birth weight, and higher rate of small for gestational age were noted in the severe preeclampsia group. Circulating EPCs in cord blood and umbilical cord plasma free VEGF were significantly decreased in severe preeclampsia compared to the control group (p = 0.009 and 0.04, respectively).

CONCLUSION

In severe preeclampsia, cord blood EPCs were reduced markedly and this was accompanied by a significant decrease in cord plasma free VEGF which is known to play a role in EPC mobilization.

The distribution of the growth factors FGF-2 and VEGF, and their receptors, in growing red deer antler

The cellular distributions of the growth factors FGF-2 and VEGF, and their receptors FGFR1, FGFR2 and FGFR3, and VEGFR-2 respectively, were visualized by immunohistochemistry and light microscopy in sections of growing red deer antler. Both of these signalling systems were widely expressed in the integument and osteocartilaginous compartments. FGF-2 was found in the same cells as all three FGFRs, indicating that FGF signalling may be principally autocrine. The patterns of labelling for VEGF and its receptor were similar to those seen for FGF-2 and FGFR-3, in both compartments. Our data are consistent with the findings of others in suggesting that FGF-2 induces expression of VEGF, to stimulate and maintain high rates of neovascularisation and angiogenesis, thereby providing nutrients to both velvet and bone as they rapidly grow and develop. The presence of FGF and VEGF and their receptors in epithelial cells suggests that these signalling systems play a role in skin development, raising the possibility that one or both may be involved in the close coupling of the coordinated growth of the integument and osteocartilage of antler, a process which is poorly understood at present.

Angiogenesis, vasculogenesis, and induction of healing in chronic wounds

A key central stage of wound healing requires neovascularization of the wound base granulation tissue. In the adult, neovascularization is now known to occur by both angiogenesis and vasculogenesis. Understanding the biology of these 2 processes offers promising new therapeutic options for patients who suffer from chronic, nonhealing ischemic wounds. The authors review the current literature on the processes of angiogenesis and vasculogenesis and how it relates to wound healing.

Association between UHMWPE particle-induced inflammatory osteoclastogenesis and expression of RANKL, VEGF, and Flt-1 in vivo

Wear debris-induced vascularized granulomatous periprosthetic tissue may augment the progress of prosthetic loosening, a major clinical problem after total joint replacement. The purpose of this study is to investigate the association of ultra-high-molecular-weight polyethylene (UHMWPE) particle-induced inflammatory osteoclastogenesis and expression of RANK/RANKL and VEGF/VEGF receptors (Flt-1 and Flk-1) using a mouse osteolysis model. UHMWPE particles were introduced into established air pouches on BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. Mice were injected with either recombinant VEGF or VEGF inhibitor (VEGF R2/F(c) Chimera). Mice without drug treatment, as well as mice injected with saline alone were included. Each group contains 10 mice. Pouch tissues were harvested 2 weeks after bone implantation for histological and molecular analysis. UHMWPE stimulation significantly increased VEGF gene expression, and exerted a lower enhancement effect on the gene expression of Flt-1 and Flk-1. UHMWPE-stimulated VEGF production was markedly reduced by VEGF inhibitor treatment. Immunofluorescent staining indicated that pouch tissue macrophages were the main source of both VEGF and Flt-1 production. A positive association was observed between tissue inflammation and the levels of VEGF and Flt-1 gene transcripts. Both RANK and RANKL gene transcripts were significantly increased by UHMWPE stimulation, which was subsequently reduced by VEGF inhibitor treatment (p<0.05). VEGF treatment increased TRAP(+) cells in pouches either with or without UHMWPE particle stimulation, and VEGF inhibitor treatment caused a significant reduction in the number of TRAP(+) cells in UHMWPE-containing pouches. This study suggests that VEGF has a role in the regulation of RANK/RANKL-mediated osteoclastogenesis, and warrant future investigations to elucidate the role of VEGF signaling in the pathogenesis of prosthetic loosening.

Differential gene and protein expression in abluminal sprouting and intraluminal splitting forms of angiogenesis

In adult skeletal muscle, abluminal sprouting or longitudinal splitting of capillaries can be initiated separately by muscle overload and elevated microcirculation shear stress respectively. In the present study, gene and protein expression patterns associated with the different forms of angiogenesis were examined using a targeted gene array (Superarray), validated by quantitative RT (reverse transcription)-PCR and immunoblots. Sprouting angiogenesis induced large changes in expression levels in genes associated with extracellular matrix remodelling, such as MMP-2 (matrix metalloproteinase-2), TIMP (tissue inhibitor of metalloproteinases), SPARC (secreted protein, acidic and rich in cysteine) and thrombospondin. Changes in neuropilin, midkine and restin levels, which may underpin changes in endothelial morphology, were seen during splitting angiogenesis. Up-regulation of VEGF (vascular endothelial growth factor), Flk-1, angiopoietin-2 and PECAM-1 (platelet/endothelial cell adhesion molecule-1) was seen in both forms of angiogenesis, representing a common angiogenic response of endothelial cells. In conclusion, the present study demonstrates that general angiogenic signals from growth factors can be influenced by the local microenvironment resulting in differing forms of capillary growth to produce a co-ordinated expansion of the vascular bed.

siRNA-mediated inhibition of angiogenesis

Small interfering RNA (siRNA) has rapidly become the agent of choice for gene function analysis through loss-of-function phenotypes. Especially in complicated (patho)physiological processes such as angiogenesis, where vast numbers of proteinaceous factors are involved, the siRNA application allows relatively fast analysis of pathways and identification of new target genes. The first studies on the therapeutic effects of siRNA in angiogenesis show that this new 'drug' class holds great promise for therapeutic intervention. Two strategies emerge: the use of unmodified or the use of complexed, targeted and/or protected nucleic acids. The challenge for clinical application will be to control off-target effects and the transient character of the sequence-specific silencing effect, and to address the targeted delivery to the cell types involved in the various stages of angiogenesis. This is especially important as clinical studies indicate a profound heterogeneity of the angiogenic vasculature.

Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part III: leucocyte activation: a new feature for platelet concentrates?

Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this third article, we investigate the immune features of this biomaterial. During PRF processing, leucocytes could also secrete cytokines in reaction to the hemostatic and inflammatory phenomena artificially induced in the centrifuged tube. We therefore undertook to quantify 5 significant cell mediators within platelet poor plasma supernatant and PRF clot exudate serum: 3 proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), an antiinflammatory cytokine (IL-4), and a key growth promoter of angiogenesis (VEGF). Our data are correlated with that obtained in plasma (nonactivated blood) and in sera (activated blood). These initial analyses revealed that PRF could be an immune regulation node with inflammation retrocontrol abilities. This concept could explain the reduction of postoperative infections when PRF is used as surgical additive.

The bone marrow-derived endothelial progenitor cell response is impaired in delayed wound healing from ischemia

OBJECTIVE

Vasculogenesis relies on the recruitment of bone marrow-derived endothelial progenitor cells (BMD EPCs) and is stimulated by tissue-level ischemia. We hypothesized that the BMD EPC response is impaired in ischemic wounds and studied the relationship between BMD EPCs and wound healing.

METHODS

We used transgenic Tie-2/LacZ mice, which carry the beta-galactosidase (beta-gal) reporter gene under Tie-2 promoter control. Wild-type mice were lethally irradiated and reconstituted with Tie-2/LacZ bone marrow. Four weeks later, the mice underwent unilateral femoral artery ligation/excision and bilateral wounding of the hindlimbs. Ischemia was confirmed and monitored with laser Doppler imaging. A subset of mice received incisional vs excisional nonischemic bilateral hindlimb wounds, without femoral ligation. Excisional wound closure was measured by using daily digital imaging and software-assisted calculation of surface area.

RESULTS

Ischemia resulted in significantly delayed wound healing and differentially affected the number of BMD EPCs recruited to wound granulation tissue and muscle underlying the wounds. At 3 days postwounding, the granulation tissue of the wound base contained significantly fewer numbers of BMD EPCs in ischemic wounds compared with the nonischemic wounds (P < .05). In contrast, significantly more BMD EPCs were present in the muscle underlying the ischemic wounds at this same time point compared with the muscle under the nonischemic wounds (P < .05). In ischemic wounds, eventual wound closure significantly correlated with a delayed rise in BMD EPCs within the wound granulation tissue (Kendall's correlation, -.811, P = .0005) and was significantly associated with a gradual recovery of hindlimb perfusion (P < .0001). By 7 days postwounding, BMD EPCs were incorporated into the neovessels in the granulation tissue. At 14 days and 75 days, BMD EPCs were rarely observed within the wounds.

CONCLUSIONS

Granulation tissue of excisional ischemic wounds showed significantly less BMD EPCs 3 days postwounding, in association with significantly delayed wound closure. However, the number of BMD EPCs were increased in ischemic hindlimb skeletal muscle, consistent with the notion that ischemia is a powerful signal for vasculogenesis. To our knowledge, this is the first report identifying a deficit in BMD EPCs in the granulation tissue of ischemic skin wounds and reporting the key role for these cells in both ischemic and nonischemic wound healing.

Vascular endothelial growth factor gene polymorphisms and idiopathic recurrent pregnancy loss

OBJECTIVE

To investigate whether four common polymorphisms (-2578C/A, -1154G/A, -634G/C, and 936C/T) of the gene encoding for vascular endothelial growth factor (VEGF) are associated with idiopathic recurrent miscarriage.

DESIGN

Prospective case-control study.

SETTING

University teaching hospital.

PATIENT(S)

Fifty-two patients with a history of three or more unexplained consecutive pregnancy losses and 82 healthy, postmenopausal controls with at least two live births and no history of pregnancy loss.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction and restriction fragment length polymorphism analysis were performed to identify the different VEGF alleles.

RESULT(S)

There was a significant difference in the -1154G/A genotype and allele frequency between women with recurrent pregnancy loss and controls. The risk of recurrent pregnancy loss was lower in the carriers of the G allele than in women carrying the A allele (odds ratio = 1.91, 95% confidence interval, 0.12-3.28). No significant association between recurrent spontaneous abortions and -2578C/A, -634G/C, and 936C/T genotypes was found. Between women with primary and secondary idiopathic recurrent miscarriage, no statistically significant differences with respect to allele frequencies were observed.

CONCLUSION(S)

This is the first report on VEGF gene polymorphisms in women with recurrent miscarriage, demonstrating that the -1154G/A VEGF gene polymorphism is associated with idiopathic recurrent abortions.

Vascular endothelial growth factor-C promotes vasculogenesis, angiogenesis, and collagen constriction in three-dimensional collagen gels

OBJECTIVE

Neovascularization, angiogenesis, and collagen constriction are essential for wound healing. We tested whether vascular endothelial growth factor-C (VEGF-C) can promote collagen constriction, capillary sprouting (angiogenesis), and invasion/migration of bone marrow-derived endothelial progenitor cells into collagen (vasculogenesis).

METHODS

We used a recently characterized three-dimensional collagen matrix assay with either monolayers of human dermal microvascular endothelial cells (HMVECs) or bone marrow-derived endothelial progenitor cells (BMD EPCs), obtained from Tie-2 LacZ transgenic mice, overlaid with an acellular layer and then a cellular layer of collagen embedded with fibroblasts, that were nontransduced or transduced with either LacZ adenoviral vector (Ad5) or VEGF-C/Ad5. The ability of VEGF-C to enhance fibroblast-mediated collagen constriction was measured, and gels overlying HMVECs or BMD EPCs were co-cultured, harvested, and assayed for HMVEC migration, sprouting, and capillary-like formation; gels containing BMD EPCs were assayed for EPC invasion/migration into the collagen extracellular matrix.

RESULTS

VEGF-C significantly increased collagen constriction and formation of capillary-like structures with true lumina (P < .05) assessed by von Willebrand factor and VEGF receptor-2 immunoassaying. VEGF-C induced a significant increase in HMVEC migration, tubular polarization, and branching sprouts associated with a significant up-regulation of membrane type 1 matrix metalloproteinase (MT1-MMP) ( P < .05). Fibroblasts were necessary to support BMD-EPC invasion/migration from the monolayer into the collagen. Moreover, fibroblasts overexpressing VEGF-C significantly enhanced EPC invasion/migration ( P < .05) into the extracellular matrix by two-fold, and this effect could not be achieved with equivalent levels of exogenous VEGF-C in the absence of fibroblasts. The addition of a soluble VEGF-C competitor protein only partially inhibited these responses, reducing the EPCs by three-fold, but significant numbers of EPCs still invaded/migrated into the extracellular matrix, suggesting that other fibroblast-specific signals also contribute to the vasculogenic response.

CONCLUSION

Fibroblast-specific expression of VEGF-C promotes collagen constriction by fibroblasts and enhances microvascular endothelial cell migration, branching, and capillary sprouting in association with up-regulating MT1-MMP expression. Fibroblasts are necessary for BMD EPC invasion/migration into collagen, and their overexpression of VEGF-C enhances this fibroblast-mediated vasculogenic effect. Collectively, these findings suggest a role for VEGF-C in multiple biologic steps required for wound healing (angiogenesis, vasculogenesis, and collagen constriction).

CLINICAL RELEVANCE

Ischemic wound healing remains an unsolved problem with no previously identified molecular target for therapeutic intervention. This study demonstrates that VEGF-C overexpression by fibroblasts stimulates multiple biologic processes known to impact wound healing, such as collagen constriction, capillary sprouting, and EPC invasion and migration through extracellular matrix. Most ischemic wounds fail to heal and frequently lead to major limb amputation. Available cytokine ointments are ineffective, and revascularization is often not technically feasible. Even when these procedures are accomplished, many ischemic wounds frequently still do not heal because of multifactorial tissue level impairments in the fibroblastic and neovascularization responses at the wound base. Our findings identify an important role for two novel tissue level targets, dermis-derived fibroblasts and VEGF-C, in collagen constriction, angiogenesis, and postnatal vasculogenesis from BMD EPCs. Thus the findings are particularly relevant to the unsolved clinical problem of ischemic wound healing.

Lysophospholipids in development: Miles apart and edging in

Sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are endogenous bioactive lipids that participate in the regulation of mammalian cell proliferation, apoptosis, migration, and angiogenesis. These processes are each critical for successful embryogenesis, raising the possibility that lysophospholipid signaling may contribute to normal animal development. In fact, recent studies in developmental model systems have established that S1P and LPA are necessary for diverse developmental programs including those required for morphogenesis of vertebrate reproductive, cardiovascular and central and peripheral nervous systems (PNS), as well as the establishment of maternal-fetal circulation and the immune system. Genetic, morphological, and biochemical characterization of developmental model systems offer powerful approaches to elucidating the molecular mechanisms of lysophospholipid signaling and its contributions to animal development and postnatal physiology. In this review, the routes of S1P and LPA metabolism and our current understanding of lysophospholipid-mediated signal transduction in mammalian cells will be summarized. The evidence implicating lysophospholipid signaling in the development of specific vertebrate systems will then be reviewed, with an emphasis on signals mediated through G protein-coupled receptors of the Edg family. Lastly, recent insights derived from the study of simple metazoan models and implications regarding lysophospholipid signaling in organisms in which Edg receptors are not conserved will be explored.