The ratio of VEGF/PEDF expression in bone marrow mesenchymal stem cells regulates neovascularization

Angiogenesis, or neovascularization, is a finely balanced process controlled by pro- and anti-angiogenic factors. Vascular endothelial growth factor (VEGF) is a major pro-angiogenic factor, whereas pigment epithelial-derived factor (PEDF) is the most potent natural angiogenesis inhibitor. In this study, the regulatory role of bone marrow stromal cells (BMSCs) during angiogenesis was assessed by the endothelial differentiation potential, VEGF/PEDF production and responses to pro-angiogenic and hypoxic conditions. The in vivo regulation of blood vessel formation by BMSCs was also explored in a SCID mouse model. Results showed that PEDF was expressed more prominently in BMSCs compared to VEGF. This contrasted with human umbilical vein endothelial cells (HUVECs) where the expression of VEGF was higher than that of PEDF. The ratio of VEGF/PEDF gene expression in BMSCs increased when VEGF concentration reached 40ng/ml in the culture medium, but decreased at 80ng/ml. Under CoCl(2)-induced hypoxic conditions, the VEGF/PEDF ratio of BMSCs increased significantly in both normal and angiogenic culture media. There was no expression of endothelial cell markers in BMSCs cultured in either pro-angiogenic or hypoxia culture conditions when compared with HUVECs. The in vivo study showed that VEGF/PEDF expression closely correlated with the degree of neovascularization, and that hypoxia significantly induced pro-angiogenic activity in BMSCs. These results indicate that, rather than being progenitors of endothelial cells, BMSCs play an important role in regulating the neovascularization process, and that the ratio of VEGF and PEDF may, in effect, be an indicator of the pro- or anti-angiogenic activities of BMSCs.     

Ratio of the vitreous vascular endothelial growth factor and pigment epithelial-derived factor in Eales disease

Eales disease (ED) is an idiopathic inflammatory venous occlusion of the peripheral retina. As neovascularization is prominent in ED, this study attempts to look at the ratio of VEGF, the angiogenic factor, and PEDF, an anti-angiogenic factor in the vitreous of ED patients in comparison with the macular hole (MH) and Proliferative Diabetic Retinopathy (PDR). Vitreous levels of VEGF and PEDF were determined in the undiluted vitreous specimen obtained from 26 ED cases, 17 PDR, and seven patients with MH. The vitreous levels of VEGF and PEDF were estimated by ELISA. The immunohistochemistry (IHC) for VEGF and PEDF were done in the epiretinal membrane of ED and PDR case. The VEGF/PEDF ratio was found to be significantly increased in ED (p = 0.014) and PDR (p = 0.000) compared to MH. However the ratio was 3.5-fold higher in PDR than ED (p = 0.009). The IHC data on the ERM specimen from ED showed the presence of VEGF and PEDF similar to PDR. The high angiogenic potential seen as the ratio of VEGF/PEDF correlates with the peak clinical onset of the disease in the age group 21–30 years and the diseases usually self-resolves above the age of 40, which is reflected by the low ratio of VEGF/PEDF. The study shows that the VEGF/PEDF ratio is significantly increased in ED though the angiogenic potential is higher in PDR than in ED. Clinically Eales Disease is known as a self-limiting disease, while PDR is a progressive disease.     

Pigment epithelium-derived factor exerts opposite effects on endothelial cells of different phenotypes

The anti-angiogenic activity of pigment epithelium-derived factor (PEDF) has recently been discovered on the basis of its inhibition of ischemia-induced retinal neovascularization in an animal model of retinopathy of the premature. Moreover PEDF inhibits the migration and proliferation of various endothelial cells maintained in culture with FGF(2). Since vascular endothelial growth factor (VEGF) is the main angiogenic factor expressed in hypervascularized retinas, we investigated the functions of PEDF on retinal endothelial cells whose angiogenic phenotype is controlled or not by long term exposure to VEGF as observed in human pathologies such as diabetic retinopathy. Here, we observed that PEDF exerts opposite effects on endothelial cells depending on their phenotype. We determined that when PEDF inhibits endothelial cell growth, it inhibits VEGF-induced MAPK activation. However, in endothelial cells cultured with VEGF, PEDF has a synergistic action on cell proliferation with VEGF, and this corresponds to increased MAPK activation.     

PEDF derived from glial Müller cells: a possible regulator of retinal angiogenesis

A precise balance between stimulators and inhibitors of angiogenesis, such as vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF), respectively, is essential for angiogenic homeostasis in ocular tissues. Retinal hypoxia is accompanied by some pathological conditions that may promote intraocular neovascularization. Here we demonstrate that retinal glial (Müller) cells express and release pigment epithelium-derived factor (PEDF). Decreasing oxygen concentrations cause strong attenuation of PEDF release resulting in enhanced VEGF/PEDF ratios. Exposure of Müller cells to VEGF suppressed PEDF release in a dose-dependent manner. This may represent a novel mechanism of ocular angiogenic homeostasis sufficient in the control of PEDF levels during normoxia or mild hypoxia but supplemented by other (hitherto unknown) mechanisms in cases of strong hypoxia. In spite of the enhanced VEGF/PEDF ratios resulting from hypoxia, conditioned media of Müller cells failed to stimulate additional proliferation of retinal endothelial cells. These findings suggest that in the ischemic retina, Müller cells generate a permissive condition for angiogenesis by secreting more VEGF and less PEDF, but the onset of retinal endothelial cell proliferation requires another triggering signal that remains to be identified.     

Down-regulation of vascular endothelial growth factor and up-regulation of pigment epithelium-derived factor: a possible mechanism for the anti-angiogenic activity of plasminogen kringle 5.

We have previously shown that intravitreal injection of plasminogen kringle 5 (K5), a potent angiogenic inhibitor, inhibits ischemia-induced retinal neovascularization in a rat model. Here we report that K5 down-regulates an endogenous angiogenic stimulator, vascular endothelial growth factor (VEGF) and up-regulates an angiogenic inhibitor, pigment epithelium-derived factor (PEDF) in a dose-dependent manner in vascular cells and in the retina. The regulation of VEGF and PEDF by K5 in the retina correlates with its anti-angiogenic effect in a rat model of ischemia-induced retinopathy. Retinal RNA levels of VEGF and PEDF are also changed by K5. K5 inhibits the p42/p44 MAP kinase activation and nuclear translocation of hypoxia-inducible factor-1alpha, which may be responsible for the down-regulation of VEGF. Down-regulation of endogenous angiogenic stimulators and up-regulation of endogenous angiogenic inhibitors, thus leading toward restoration of the balance in angiogenic control, may represent a mechanism for the anti-angiogenic activity of K5.     

Pigment epithelium-derived factor inhibits retinal and choroidal neovascularization.

In this study, we investigated whether overexpression of pigment epithelium-derived factor (PEDF) by gene transfer can inhibit neovascularization by testing its effect in three different models of ocular neovascularization. Intravitreous injection of an adenoviral vector encoding PEDF resulted in expression of PEDF mRNA in the eye measured by RT-PCR and increased immunohistochemical staining for PEDF protein throughout the retina. In mice with laser-induced rupture of Bruch's membrane, choroidal neovascularization was significantly reduced after intravitreous injection of PEDF vector compared to injection of null vector or no injection. Subretinal injection of the PEDF vector resulted in prominent staining for PEDF in retinal pigmented epithelial cells and strong inhibition of choroidal neovascularization. In two models of retinal neovascularization (transgenic mice with increased expression of vascular endothelial growth factor (VEGF) in photoreceptors and mice with oxygen-induced ischemic retinopathy), intravitreous injection of null vector resulted in decreased neovascularization compared to no injection, but intravitreous injection of PEDF vector resulted in further inhibition of neovascularization that was statistically significant. These data suggest that sustained increased intraocular expression of PEDF by gene therapy might provide a promising approach for treatment of ocular neovascularization.     

Human apolipoprotein E2 transgenic mice show lipid accumulation in retinal pigment epithelium and altered expression of VEGF and bFGF in the eyes

We investigated the human apolipoprotein E2 (apoE2) transgenic mouse as an animal model system for age-related macular degeneration (AMD). Transgenic mice expressing human apoE2 and C57BL/6J mice were fed normal chow or a high-fat diet for 4 weeks. Eyes were collected from the mice and lipid deposits in retinal pigment epithelium (RPE) were assessed using electron microscopy. The expressions of apoE, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and pigment-epithelium derived factor (PEDF), which are molecular markers for angiogenesis, were assessed with immunohistochemistry. Eyes from apoE2 mice, regardless of diet, contained lipid accumulation in RPE under electron microscopy, whereas control C57BL/6J eyes did not. Lipid accumulation was found predominantly in the RPE and the Bruch's membrane and increased in the eyes of apoE2 mice after one month of a high-fat diet (8 +/- 2 per 50 microm2 for normal chow and 11 +/- 2 per 50 microm2, p < 0.05). ApoE expression was similar in the apoE2 and control mice; however, VEGF and bFGF were overexpressed in the retinal pigment epithelium of apoE2 eyes compared with control eyes, and PEDF expression was slightly decreased. These expression patterns of VEGF, bFGF, and PEDF suggest angiogenesis is progressing in apoE2 eyes. In conclusion, the eyes of apoE2 mice develop typical lipid accumulations, a common characteristic of AMD, making them a suitable animal model for AMD. The expression profile of VEGF and bFGF on the retinal pigment epithelium suggests that apoE2 may induce neovascularization by altering angiogenic cytokines.     

Effect of high glucose concentration on VEGF and PEDF expression in cultured retinal Müller cells

To explore the effect of high glucose concentration on the expression of vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) in the cultured rat retinal Müller cells. Rat Müller cells were cultured and RT-PCR and Western-blot analysis were used to measure the levels of VEGF and PEDF in cultured Müller cells at different high glucose concentrations. Under 10, 20, 30 mmol/L high glucose conditions, the levels of VEGF mRNA and protein increased and the levels of PEDF mRNA and protein decreased. These results suggest that the VEGF and PEDF expression in Müller cells are unbalance under high glucose concentration, which contribute to retinal neovascularization in diabetic retinopathy.     

Vascular endothelial growth factor upregulates pigment epithelium-derived factor expression via VEGFR-1 in human retinal pigment epithelial cells

We previously demonstrated that differentiated retinal pigment epithelial (RPE) cells express high levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF), and a critical balance between VEGF and PEDF is important to prevent the development of choroidal neovascularization. We report here that VEGF secreted by RPE cells upregulates PEDF expression via VEGFR-1 in an autocrine manner. PEDF mRNA and protein expression was downregulated by neutralizing antibody against VEGF in differentiated human RPE cells. VEGFR-1 neutralization decreased PEDF mRNA and protein expression whereas anti-VEGFR-2 antibody had no effect. Addition of placenta growth factor (PlGF) restored PEDF expression in the presence of anti-VEGF antibody. These results demonstrate a regulatory interaction between angiogenesis stimulators and inhibitors to maintain homeostasis in normal human retina.     

视网膜病变早产儿视网膜厚度与血清血管新生细胞因子PEDF和VEGF表达的相关性

摘要 目的：探讨视网膜病变早产儿视网膜厚度与血清血管内皮生长因子（vascular endothelial growth factor,VEGF）、色素上皮衍生因子（pigment epithelium derived factor,PEDF）表达的相关性。方法：采用回顾性研究方法,2016年2月到2021年6月选择在新疆维吾尔自治区人民医院眼科就诊的早产儿视网膜病变患儿80例作为观察组,同期选择足月视网膜病变患儿80例作为对照组,测定两组患儿视网膜厚度,检测血管新生细胞因子-PEDF与VEGF表达情况,对两者进行相关性分析。结果：观察组患儿的颞侧、上方、下方的视网膜神经纤维层厚度都显著高于对照组,两组对比差异明显(P<0.05)。观察组患儿的血清VEGF水平高于对照组,PEDF水平低于对照组,对比差异有统计学意义(P<0.05)。在观察组患儿中,Pearson相关系数相关性分析显示血清PEDF水平与VEGF水平呈现显著负相关性(r=-0.341, P<0.05);患儿颞侧、上方、下方的视网膜神经纤维层厚度与血清PEDF水平成显著负相关性(P<0.05),与血清VEGF水平成显著正相关性(P<0.05)。多元logistic回归分析显示血清PEDF、VEGF水平都为导致早产儿视网膜厚度发生的重要因素(P<0.05)。结论：早产儿视网膜厚度均高于足月儿,血管新生细胞因子PEDF、VEGF呈现异常表达情况,视网膜厚度与PEDF、VEGF的表达都有一定的相关性,PEDF、VEGF也为导致早产儿视网膜病变发生的重要因素。     

Cigarette smoke-related hydroquinone dysregulates MCP-1, VEGF and PEDF expression in retinal pigment epithelium in vitro and in vivo

Background

Age-related macular degeneration (AMD) is the leading cause of legal blindness in the elderly population. Debris (termed drusen) below the retinal pigment epithelium (RPE) have been recognized as a risk factor for dry AMD and its progression to wet AMD, which is characterized by choroidal neovascularization (CNV). The underlying mechanism of how drusen might elicit CNV remains undefined. Cigarette smoking, oxidative damage to the RPE and inflammation are postulated to be involved in the pathophysiology of the disease. To better understand the cellular mechanism(s) linking oxidative stress and inflammation to AMD, we examined the expression of pro-inflammatory monocyte chemoattractant protein-1 (MCP-1), pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial derived factor (PEDF) in RPE from smoker patients with AMD. We also evaluated the effects of hydroquinone (HQ), a major pro-oxidant in cigarette smoke on MCP-1, VEGF and PEDF expression in cultured ARPE-19 cells and RPE/choroids from C57BL/6 mice.

Principal Findings

MCP-1, VEGF and PEDF expression was examined by real-time PCR, Western blot, and ELISA. Low levels of MCP-1 protein were detected in RPE from AMD smoker patients relative to controls. Both MCP-1 mRNA and protein were downregulated in ARPE-19 cells and RPE/choroids from C57BL/6 mice after 5 days and 3 weeks of exposure to HQ-induced oxidative injury. VEGF protein expression was increased and PEDF protein expression was decreased in RPE from smoker patients with AMD versus controls resulting in increased VEGF/PEDF ratio. Treatment with HQ for 5 days and 3 weeks increased the VEGF/PEDF ratio in vitro and in vivo.

Conclusion

We propose that impaired RPE-derived MCP-1-mediated scavenging macrophages recruitment and phagocytosis might lead to incomplete clearance of proinflammatory debris and infiltration of proangiogenic macrophages which along with increased VEGF/PEDF ratio favoring angiogenesis might promote drusen accumulation and progression to CNV in smoker patients with dry AMD.     

Long-Term Retinal PEDF Overexpression Prevents Neovascularization in a Murine Adult Model of Retinopathy

Neovascularization associated with diabetic retinopathy (DR) and other ocular disorders is a leading cause of visual impairment and adult-onset blindness. Currently available treatments are merely palliative and offer temporary solutions. Here, we tested the efficacy of antiangiogenic gene transfer in an animal model that mimics the chronic progression of human DR. Adeno-associated viral (AAV) vectors of serotype 2 coding for antiangiogenic Pigment Epithelium Derived Factor (PEDF) were injected in the vitreous of a 1.5 month-old transgenic model of retinopathy that develops progressive neovascularization. A single intravitreal injection led to long-term production of PEDF and to a striking inhibition of intravitreal neovascularization, normalization of retinal capillary density, and prevention of retinal detachment. This was parallel to a reduction in the intraocular levels of Vascular Endothelial Growth Factor (VEGF). Normalization of VEGF was consistent with a downregulation of downstream effectors of angiogenesis, such as the activity of Matrix Metalloproteinases (MMP) 2 and 9 and the content of Connective Tissue Growth Factor (CTGF). These results demonstrate long-term efficacy of AAV-mediated PEDF overexpression in counteracting retinal neovascularization in a relevant animal model, and provides evidence towards the use of this strategy to treat angiogenesis in DR and other chronic proliferative retinal disorders.     

Angiopoietin-2 enhances retinal vessel sensitivity to vascular endothelial growth factor

Increased expression of vascular endothelial growth factor (VEGF) in the retina starting after postnatal day (P)7 results in neovascularization originating from deep retinal capillaries, but not those in the superficial capillary bed. Doxycycline was administered starting P0 to double transgenic mice with inducible expression of VEGF in the retina. These mice showed proliferation and dilation of superficial retinal capillaries, indicating that at this stage of development, the superficial capillaries are sensitive to the effects of VEGF. Angiopoietin-2 (Ang2) is expressed along the surface of the retina for several days after birth, but by P7 and later, Ang2 is only expressed in the region of the deep capillary bed. In mice with ubiquitous doxycycline-inducible expression of Ang2, in the absence of doxycycline, intravitreous injection of a gutless adenoviral vector expressing VEGF (AGV.VEGF) resulted in neovascularization of the cornea and iris, but no retinal neovascularization. After treatment with doxycycline to induce Ang2 expression, intravitreous injection of AGV.VEGF caused retinal neovascularization in addition to corneal and iris neovascularization. The retinal neovascularization originated from both the superficial and deep capillary beds. These data suggest that Ang2 promotes sensitivity to the angiogenic effects of VEGF in retinal vessels.     

Hypoxic induction of endothelial cell growth factors in retinal cells: identification and characterization of vascular endothelial growth factor (VEGF) as the mitogen.

BACKGROUND: New vessel growth is often associated with ischemia, and hypoxic tissue has been identified as a potential source of angiogenic factors. In particular, ischemia is associated with the development of neovascularization in a number of ocular pathologies. For this reason, we have studied the induction of endothelial cell mitogens by hypoxia in retinal cells. MATERIALS AND METHODS: Human retinal pigment epithelium (hRPE) were grown under normoxic and hypoxic conditions and examined for the production of endothelial mitogens. Northern analysis, biosynthetic labeling and immunoprecipitation, and ELISA were used to assess the levels of vascular endothelial growth factor/vascular permeability factor (VEGF) and basic fibroblast growth factor (bFGF), two endothelial cell mitogens and potent angiogenic factors. Soluble receptors for VEGF were employed as competitive inhibitors to determine the contribution of the growth factor to the hypoxia-stimulated mitogen production. RESULTS: Following 6-24 hr of hypoxia, confluent and growing cultures of hRPE increase their levels of VEGF mRNA and protein synthesis. Biosynthetic labeling studies and RT-PCR analysis indicate that the cells secrete VEGF121 and VEGF165, the soluble forms of the angiogenic factor. In contrast, hRPE cultured under hypoxic conditions show reduced steady-state levels of basic fibroblast growth factor (bFGF) mRNA and decreased bFGF protein synthesis. Unlike VEGF, bFGF is not found in conditioned media of hRPE following 24 hr of hypoxia. Using a soluble high-affinity VEGF receptor as a competitive inhibitor of VEGF, we demonstrate that a VEGF-like activity is the sole hypoxia-inducible endothelial mitogen produced by cultured hRPE. CONCLUSIONS: From this comparison we conclude that hRPE do not respond to hypoxia with a general, nonspecific increase in the overall levels of growth factors, as is seen during cell wounding responses or serum stimulation. The physiological relevance of data from this in vitro model are affirmed by separate studies in an animal model of retinal ischemia-induced ocular neovascularization (1) in which retina-derived VEGF levels have been shown to correlate spatio-temporally with the onset of angiogenesis. Taken together, these data support the hypothesis that the induction of VEGF by hypoxia mediates the rapid, initial angiogenic response to retinal ischemia.     

Proliferative diabetic retinopathy is associated with a low level of the natural ocular anti-angiogenic agent pigment epithelium-derived factor (PEDF) in aqueous humor. a pilot study.

Retinopathy is the most common microvascular diabetes complication and represents a major threat to the eyesight. The aim of this study was to address the role of pro- and anti-angiogenic molecules in diabetic retinopathy in the aqueous humor of the eye. Aqueous humor was collected at cataract surgery from 19 diabetic patients and from 13 age- and sex-matched normoglycemic controls. Levels of pro-angiogenic vascular endothelial growth factor (VEGF) and angiogenic inhibitor pigment epithelium-derived factor (PEDF) were determined. Angiogenic activity of the aqueous humor was quantified by measuring its effect on the migration of capillary endothelial cells. In the aqueous fluid, VEGF levels were increased in diabetics (mean values: 501 vs. 367 pg/ml; p = 0.05), compared to controls. PEDF was found to be decreased in diabetics (mean values: 2080 vs. 5780 ng/ml; p = 0.04) compared to controls. In seven diabetic patients with proliferative retinopathy, the most profound finding was a significant decrease of the PEDF level (mean value: 237 ng/ml), whereas VEGF levels were comparable to diabetic patients without proliferation (mean value: 3153; p = 0.003). Angiogenic activity in samples of patients from the control group was generally inhibitory due to PEDF, and inhibition was blocked by neutralizing antibodies to PEDF. Likewise, in diabetics without proliferation, angiogenic activity was also blocked by antibodies to PEDF. We will demonstrate here that the level of the natural ocular anti-angiogenic agent PEDF is inversely associated with proliferative retinopathy. PEDF is an important negative regulator of angiogenic activity of aqueous humor. Our data may have implications for the development of novel regimens for diabetic retinopathy.     

Intraocular gutless adenoviral-vectored VEGF stimulates anterior segment but not retinal neovascularization

Vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1) have been implicated as important stimulatory factors for retinal neovascularization. In this study, we used intraocular gene transfer with gutless adenoviral (AGV) vectors to determine the effect of increased intraocular expression of VEGF, IGF-1, or sphingosine kinase (SPK), which produces sphingosine-1-phosphate, another angiogenic factor. Retinal neovascularization did not occur from intravitreous AGV-vectored VEGF, IGF-1, SPK, or combined VEGF and IGF-1, except occasionally adjacent to the retinal penetration site from the injection. However, corneal and iris neovascularization occurred after 2 weeks in all eyes injected with AGV.VEGF, but not those injected with only AGV.IGF-1 or AGV.SPK. These data suggest that the superficial capillary bed of the retina is relatively insensitive to VEGF, IGF-1, or SPK in adult mice, except when combined with retinal trauma. However, AGV-vectored VEGF is sufficient to consistently cause severe corneal and iris neovascularization. This provides a model for anterior segment neovascularization, which unlike previous models is relatively inexpensive and is not plagued by spontaneous regression, and therefore, may be useful for identification of new treatments.     

Vitreous TIMP-1 levels associate with neovascularization and TGF-β2 levels but not with fibrosis in the clinical course of proliferative diabetic retinopathy

In proliferative diabetic retinopathy (PDR), vascular endothelial growth factor (VEGF) and CCN2 (connective tissue growth factor; CTGF) cause blindness by neovascularization and subsequent fibrosis. This angio-fibrotic switch is associated with a shift in the balance between vitreous levels of CCN2 and VEGF in the eye. Here, we investigated the possible involvement of other important mediators of fibrosis, tissue inhibitor of metalloproteinases (TIMP)-1 and transforming growth factor (TGF)-β2, and of the matrix metalloproteinases (MMP)-2 and MMP-9, in the natural course of PDR. TIMP-1, activated TGF-β2, CCN2 and VEGF levels were measured by ELISA in 78 vitreous samples of patients with PDR (n = 28), diabetic patients without PDR (n = 24), and patients with the diabetes-unrelated retinal conditions macular hole (n = 10) or macular pucker (n = 16), and were related to MMP-2 and MMP-9 activity on zymograms and to clinical data, including degree of intra-ocular neovascularization and fibrosis. TIMP-1, CCN2 and VEGF levels, but not activated TGF-β2 levels, were significantly increased in the vitreous of diabetic patients, with the highest levels in PDR patients. CCN2 and the CCN2/VEGF ratio were the strongest predictors of degree of fibrosis. In diabetic patients with or without PDR, activated TGF-β2 levels correlated with TIMP-1 levels, whereas in PDR patients, TIMP-1 levels, MMP-2 and proMMP-9 were associated with degree of neovascularization, like VEGF levels, but not with fibrosis. We confirm here our previous findings that retinal fibrosis in PDR patients is significantly correlated with vitreous CCN2 levels and the CCN2/VEGF ratio. In contrast, TIMP-1, MMP-2 and MMP-9 appear to have a role in the angiogenic phase rather than in the fibrotic phase of PDR.     

Decreased expression of pigment epithelium derived factor (PEDF), an inhibitor of angiogenesis, in placentas of unexplained stillbirths

Normal placental vascular development depends upon the complex interactions between angiogenic inducers and inhibitors within the placenta. Alterations within the placental microenvironment can promote an imbalance in angiogenic mediators which may be associated with adverse perinatal outcomes. The purpose of this study was to investigate the placentas of infants with unexplained stillbirth as compared to live-born infants and to determine whether alterations in angiogenic inducer vascular endothelial growth factor (VEGF) or inhibitor pigment epithelium-derived factor (PEDF) are associated with altered angiogenesis, vascular remodeling and stillbirth. Placentas of 22 unexplained stillbirths and 44 age-matched live-born controls were scored for microvascular density (MVD), vasculopathy and microvascular permeability. A subset was scored for expression of angiogenic inducer VEGF and inhibitor pigment epithelium-derived factor. Stillborn placentas demonstrated higher MVD than controls (mean+SD: 116.6+/-46.3 v. 60.8+/-13.5, respectively, p<0.001). Vasculopathy was present in 10/22 (45%) stillbirths compared to 0/44 (0%) controls (p<0.001); increased vascular permeability was present in 15/22 (68%) cases and 5/44 (11%) controls (p<0.001). PEDF expression was significantly lower in stillborn placentas (1.7+/-0.3) than live-born controls (3.6+/-0.8, p<0.01) while VEGF expression was similar (3.3+/-0.7 v. 3.7+/-0.4, respectively, p>0.05). In conclusion, we found that unexplained stillbirth is associated with loss of angiogenic inhibitor PEDF, vasculopathy and heightened angiogenesis in the placenta.     

Pigment epithelium-derived factor in ulcerative colitis: possible relationship with disease activity

OBJECTIVES: Pigment epithelium-derived factor (PEDF) is an endogenous most potential angiogenic inhibitor and increased expression of PEDF in intestinal mucosa specimens was shown in the course of ulcerative colitis (UC). The aim of the present study was to evaluate serum concentration of pigment epithelium-derived growth factor, a potent anti-angiogenic factor and its possible association with vascular endothelial growth factor (VEGF) levels and disease activity. METHODS: Concentrations of PEDF and VEGF were measured in sera of 33 patients (13 females and 20 males) with active UC. RESULTS: There was significant increase of serum PEDF (32.3+/-2.9 vs. 20.6+/-4.7 ng/mL, P<0.05) as well as VEGF (326.4+/-58.1 vs. 110.9+/-15.7 pg/mL, P<0.05) in UC patients compared to healthy controls. Serum PEDF showed strong, positive correlation with endoscopic score (r=0.622, P<0.001), while such association was absent in respect to VEGF (r=0.05, P=0.77). In contrast serum VEGF decreased in severe UC comparing to patients with a mild course of disease, however the difference was not significant (274.9+/-64.9 vs. 360.4+/-103.4 pg/mL, P=0.53). CONCLUSIONS: Increase in serum PEDF during UC, especially in severe forms of disease suggests its involvement in UC pathogenesis.