Biomedical subjects

Mike Boulton

Publications and source records attributed to Mike Boulton.

18 recordsLinked to original sources

PubMed2006

Vascular endothelial growth factor C promotes survival of retinal vascular endothelial cells via vascular endothelial growth factor receptor-2.

AIM: To determine vascular endothelial growth factor C (VEGF-C) expression in retinal endothelial cells, its antiapoptotic potential and its putative role in diabetic retinopathy. METHOD: Cultured retinal endothelial cells and pericytes were exposed to tumour necrosis factor (TNF)alpha and VEGF-C expression determined by reverse transcriptase-polymerase chain reaction. Secreted VEGF-C protein levels in conditioned media from endothelial cells were examined by western blotting analysis. The ability of VEGF-C to prevent apoptosis induced by TNFalpha or hyperglycaemia in endothelial cells was assessed by flow cytometry. The expression of VEGF-C in diabetic retinopathy was studied by immunohistochemistry of retinal tissue. RESULT: VEGF-C was expressed by both vascular endothelial cells and pericytes. TNFalpha up regulated both VEGF-C and vascular endothelial growth factor receptor-2 (VEGFR)-2 expression in endothelial cells in a dose-dependent manner, but had no effect on VEGFR-3. Flow cytometry results showed that VEGF-C prevented endothelial cell apoptosis induced by TNFalpha and hyperglycaemia and that the antiapoptotic effect was mainly via VEGFR-2. In pericytes, the expression of VEGF-C mRNA remained stable on exogenous TNFalpha treatment. VEGF-C immunostaining was increased in retinal vessels in specimens with diabetes compared with retinal specimens from controls without diabetes. CONCLUSION: In retinal endothelial cells, TNFalpha stimulates the expression of VEGF-C, which in turn protects endothelial cells from apoptosis induced by TNFalpha or hyperglycaemia via VEGFR-2 and thus helps sustain retinal neovascularisation.

Animals↗

PubMed2006

Decreased pigment epithelium-derived factor expression in human breast cancer progression.

PURPOSE: The aim of this study was to correlate the expression of pigment epithelium-derived factor (PEDF), a potent endogenous antiangiogenic molecule, with severity and prognosis in breast cancer. EXPERIMENTAL DESIGN: To investigate the gene expression profile of PEDF in human breast cancer in relation to a patient's clinical variables, we examined human breast cancer tissue (n = 119), background breast tissue (n = 33), and a range of cell lines for mRNA and protein levels of PEDF by using reverse transcription PCR, real-time quantitative PCR, immunohistochemistry, and ELISA. RESULTS: By using reverse transcription PCR, real-time quantitative PCR, immunohistochemistry, and ELISA, PEDF expression was found to be dramatically decreased in breast cancer. An overall outlook for the patients inversely correlated with PEDF mRNA levels. Exogenous PEDF inhibits endothelial tubule formation induced by breast cancer cell-conditioned medium, in vitro. CONCLUSION: These observations collectively support the hypothesis that a lack of PEDF expression is a potent factor for the enhancement of tumor growth and angiogenesis in breast cancer.

Breast Neoplasms↗

PubMed2006

The contribution of DNA repair and antioxidants in determining cell type-specific resistance to oxidative stress.

The aims of this study were; (i) to elucidate the mechanisms involved in determining cell type-specific responses to oxidative stress and (ii) to test the hypothesis that cell types which are subjected to high oxidative burdens in vivo, have greater oxidative stress resistance. Cultures of the retinal pigment epithelium (RPE), corneal fibroblasts, alveolar type II epithelium and skin epidermal cells were studied. Cellular sensitivity to H2O2 was determined by the MTT assay. Cellular antioxidant status (CuZnSOD, MnSOD, GPX, CAT) was analyzed with enzymatic assays and the susceptibility and repair capacities of nuclear and mitochondrial genomes were assessed by QPCR. Cell type-specific responses to H2O2 were observed. The RPE had the greatest resistance to oxidative stress (P>0.05; compared to all other cell types) followed by the corneal fibroblasts (P < 0.05; compared to skin and lung cells). The oxidative tolerance of the RPE coincided with greater CuZnSOD, GPX and CAT enzymatic activity (P < 0.05; compared to other cells). The RPE and corneal fibroblasts both had up-regulated nDNA repair post-treatment (P < 0.05; compared to all other cells). In summary, variations in the synergistic interplay between enzymatic antioxidants and nDNA repair have important roles in influencing cell type-specific vulnerability to oxidative stress. Furthermore, cells located in highly oxidizing microenvironments appear to have more efficient oxidative defence and repair mechanisms.

Antioxidants↗

PubMed2006

Differential regulation of key stages in early corneal wound healing by TGF-beta isoforms and their inhibitors.

PURPOSE: Inhibition of TGF-beta reduces myofibroblast differentiation and fibrosis in the cornea. Determining the actions of distinct TGF-beta isoforms and their inhibitors during early corneal wound healing is an essential step in guiding therapeutic intervention. METHODS: Bovine serum-free corneal cell and wounded organ cultures were challenged with a range of concentrations of TGF-beta1, -beta2, and -beta3; IL-10; and neutralizing human monoclonal antibodies (mAbs) against TGF-beta1 (CAT-192) or -beta2, (CAT-152). Cultures were assessed for re-epithelialization, proliferation (cell counts and cresyl violet assay), morphology (histologic examination), repopulation of the area under the wound, and myofibroblast transformation (alpha-smooth muscle actin) between 0 and 5 days. RESULTS: TGF-beta1 delayed re-epithelialization, increased repopulation of the stroma, increased keratocyte proliferation and was the only isoform to promote myofibroblast differentiation. The anti-TGF-beta1 mAb, CAT-192 promoted re-epithelialization and reduced repopulation of the stroma. Exogenous TGF-beta3 had little effect on re-epithelialization but reduced repopulation of the stroma. IL-10 promoted corneal re-epithelialization at low doses but inhibited this response at high doses. Stromal repopulation was prevented by all doses of IL-10. TGF-beta2 or the anti-TGF-beta2 mAb, CAT-152 had little effect on any repair parameter. CONCLUSIONS: The results confirm TGF-beta1 as the principal isoform in corneal wound healing and suggest that inhibition of the action of TGF-beta1 can promote corneal wound healing. Treatment with the anti-TGF-beta1 mAb CAT-192 accelerates corneal re-epithelialization but reduces cell repopulation of the stroma. The cytokines TGF-beta3 and IL-10 have opposing actions to that of TGF-beta1.

Animals↗

PubMed2006

Dietary antioxidants provide differential subcellular protection in epithelial cells.

This study aimed to evaluate the organelle-specific antioxidant/pro-oxidant actions of clinically important dietary antioxidants against oxidative stress. An in vitro cellular model was employed to investigate the antioxidant/pro-oxidant effects of various concentrations (1, 10 and 100 microM) of ascorbic acid, alpha-tocopherol and beta-carotene during H2O2-induced oxidative stress. Damage to nuclear and mitochondrial genomes was analyzed by quantitative polymerase chain reaction and oxidation of membrane lipids was measured via colorimetric assays. The key findings were: (i) dietary antioxidants conferred a dose-dependent protective effect (with a pro-oxidant shift at higher concentrations); (ii) the protection conferred to different sub-cellular organelles is highly specific to the dietary antioxidant; (iii) the mtDNA is highly sensitive to oxidative attack compared to nDNA (P < 0.05); and (iv) mtDNA protection conferred by dietary antioxidants was required to improve protection against oxidative-induced cell death. This study shows that antioxidant-induced protection of mtDNA is an important target for future oxidative stress therapies.

Adult↗

PubMed2005

Vascular endothelial growth factor-induced endothelial cell proliferation is regulated by interaction between VEGFR-2, SH-PTP1 and eNOS.

VEGF receptor-2 plays a critical role in endothelial cell proliferation during angiogenesis. However, regulation of receptor activity remains incompletely explained. Here, we demonstrate that VEGF stimulates microvascular endothelial cell proliferation in a dose-dependent manner with VEGF-induced proliferation being greatest at 5 and 100 ng/ml and significantly reduced at intermediate concentrations (>50% at 20 ng/ml). Neutralization studies confirmed that signaling occurs via VEGFR-2. In a similar fashion, ERK/MAPK is strongly activated in response to VEGF stimulation as demonstrated by its phosphorylation, but with a decrease in phosphoryation at 20 ng/ml VEGF. Immunoblotting analysis revealed that VEGF did not cause a dose-dependent change in expression of VEGFR-2 but instead resulted in reduced phosphorylation of VEGFR-2 when cells were exposed to 10 and 20 ng/ml of VEGF. VEGFR-2 dephosphorylation was associated with an increase in the protein tyrosine phosphatase, SH-PTP1, and endothelial nitric oxide synthase (eNOS). Immunoprecipitation and selective immunoblotting confirmed the association between VEGFR-2 dephosphorylation and the upregulation of SH-PTP1 and eNOS. Transfection of endothelial cells with antisense oligonucleotide against VEGFR-2 completely abolished VEGF-induced proliferation, whereas anti SH-PTP1 dramatically increased VEGF-induced proliferation by 1 and 5-fold at 10 and 200 ng/ml VEGF, respectively. Suppression of eNOS expression only abolished endothelial cell proliferation at VEGF concentrations above 20 ng/ml. Taken together, these results indicate that activation of VEGFR-2 by VEGF enhances SH-PTP1 activity and eNOS expression, which in turn lead to two diverse events: one is that SH-PTP1 dephosphorylates VEGFR-2 and ERK/MAPK, which weaken VEGF mitogenic activity, and the other is that eNOS increases nitric oxide production which in turn lowers SH-PTP1 activity via S-nitrosylation.

Animals↗

PubMed2005

Withdrawal: Pigment epithelium-derived factor inhibits angiogenesis via regulated intracellular proteolysis of vascular endothelial growth factor receptor 1.

Pigment epithelium-derived factor (PEDF) has been identified as one of the most potent of endogenous negative regulators of blood vessel growth in the body. Here we report that PEDF is able to inhibit growth factor-induced angiogenesis in microvascular endothelial cells through a novel pathway requiring cleavage and intracellular translocation of the transmembrane domain of the VEGFR-1. Analysis of the subcellular distribution of VEGFR-1 revealed the appearance of an 80-kDa C-terminal domain in the cytosol of cells treated with VEGF and PEDF that correlated with a decrease of the full-length receptor in the nuclear and cytoskeletal fractions. This regulated intramembrane proteolysis is dependent on gamma-secretase because inhibition of gamma-secretase abolished the inhibitory effect of PEDF on VEGF-induced angiogenesis as well as VEGFR-1 cleavage. The addition of PEDF to microvascular endothelial cells significantly increases gamma-secretase activity even in the absence of VEGF, showing that VEGF binding to VEGF-R1 is essential for substrate availability. This increase in activity was associated with translocation of presenilin 1 from the perinuclear region to the cell membrane. PEDF was also able to inhibit VEGF-induced phosphorylation of VEGFR-1. Taken together we have identified two novel pathways by which PEDF inhibits VEGF-induced angiogenesis: regulated intramembrane proteolysis and inhibition of phosphorylation. This confirms the importance of PEDF and VEGFR-1 in the negative regulation of angiogenesis.

Amyloid Precursor Protein Secretases↗

PubMed2005

Placenta growth factor is over-expressed and has prognostic value in human breast cancer.

Placenta growth factor (PlGF) belongs to the vascular endothelial growth factor (VEGF) family, a group of angiogenic factors that are crucial for tumour angiogenesis. Very little is known about the significance of PlGF in human cancer. We hypothesise that PlGF may have a potent influence in breast cancer. This study examined PlGF levels in human breast cancer in relation to patient's clinical parameters. PlGF expression and distribution was examined quantitatively using real-time quantitative polymerase chain reaction (Q-PCR) on a cohort of human breast cancer tissue (n = 119) and background breast tissue (n = 33), qualitatively using reverse transcriptase polymerase chain reaction (RT-PCR) on a range of cell lines, and immunohistochemically on patient samples. All these techniques revealed that PlGF expression was dramatically increased (P = 0.028) in breast cancer tissues compared with normal breast tissue. We demonstrate that PlGF displays prognostic value through analysis of patient survival status (6-year follow-up), as elevated levels of PlGF were significantly associated (P = 0.017) with recurrence, metastasis and patient mortality. Our study has shown that PlGF is over-expressed in breast cancer tissues and correlates with patient prognosis, and is likely to play a major role in the pathogenesis of tumours.

Breast Neoplasms↗

PubMed2005

Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye.

BACKGROUND: Dry eye is a common condition, affecting approximately 10-20% of the adult population. Artificial tears are often effective in relieving symptoms in mild and moderate dry eye by replenishing deficient tear volume. Sodium hyaluronate has been proposed as a component in artificial tears, due to its viscoelastic rheology. This paper reports on a study carried out to assess the efficacy of two recently developed eyedrops containing 0.1% and 0.3% sodium hyaluronate (SH) in the treatment of moderate dry eye. METHODS: Thirteen subjects were recruited with moderate dry eye. Forty microlitres of 0.1% SH, 0.3% SH, or 0.9% saline were instilled in both eyes, and the subjects' symptom intensity and non-invasive break-up time (NIBUT) were measured at 5, 15, 30, 45, and 60 min, and then hourly, until 6 h after drop instillation. This was repeated twice following an interval of 7(+/-1) days, but with a different treatment so that at the end of the final visit each subject had trialled all products. Drop allocation was randomized and double-masked. RESULTS: Both symptoms and NIBUT improved with all treatments. These changes were of a larger magnitude and longer duration with the SH containing eyedrops than with saline. SH of 0.3% tended to perform better than 0.1% SH and achieved statistical significance (P=0.04) for NIBUT when considered over the whole 6-h study period. CONCLUSIONS: Sodium hyaluronate of 0.1% and 0.3% reduces symptoms of ocular irritation and lengthens NIBUT in subjects with moderate dry eye more effectively than saline, in terms of peak effect and duration of action.

Administration, Topical↗

PubMed2005

Blue light induces mitochondrial DNA damage and free radical production in epithelial cells.

Exposure of biological chromophores to ultraviolet radiation can lead to photochemical damage. However, the role of visible light, particularly in the blue region of the spectrum, has been largely ignored. To test the hypothesis that blue light is toxic to non-pigmented epithelial cells, confluent cultures of human primary retinal epithelial cells were exposed to visible light (390-550 nm at 2.8 milliwatts/cm2) for up to 6 h. A small loss of mitochondrial respiratory activity was observed at 6 h compared with dark-maintained cells, and this loss became greater with increasing time. To investigate the mechanism of cell loss, the damage to mitochondrial and nuclear genes was assessed using the quantitative PCR. Light exposure significantly damaged mitochondrial DNA at 3 h (0.7 lesion/10 kb DNA) compared with dark-maintained controls. However, by 6 h of light exposure, the number of lesions was decreased in the surviving cells, indicating DNA repair. Isolated mitochondria exposed to light generated singlet oxygen, superoxide anion, and the hydroxyl radical. Antioxidants confirmed the superoxide anion to be the primary species responsible for the mitochondrial DNA lesions. The effect of lipofuscin, a photoinducible intracellular generator of reactive oxygen intermediates, was investigated for comparison. Exposure of lipofuscin-containing cells to visible light caused an increase in both mitochondrial and nuclear DNA lesions compared with non-pigmented cells. We conclude that visible light can cause cell dysfunction through the action of reactive oxygen species on DNA and that this may contribute to cellular aging, age-related pathologies, and tumorigenesis.

Antioxidants↗

PubMed2005

RPE lipofuscin and its role in retinal pathobiology.

Emerging evidence indicates that the autofluorescent pigments that accumulate as lipofuscin in retinal pigment epithelial (RPE) cells may reach levels that contribute to a decline in cell function. Since recent findings with respect to the origin, composition and adverse effects of RPE lipofuscin have informed our view of this material, the goal of this article is to review our current understanding of these issues.

Aging↗

PubMed2005

Hepatocyte growth factor and keratinocyte growth factor regulation of epithelial and stromal corneal wound healing.

PURPOSE: To investigate the effects of hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) on early wound healing in the corneal epithelium and stroma. SETTING: Cell and Molecular Biology Unit, Department of Optometry and Vision Sciences, Cardiff University, and the Cardiff Institute of Tissue Engineering and Repair, Cardiff, United Kingdom. METHODS: Corneal keratocyte cell cultures and wounded corneal organ cultures (both maintained in serum-free conditions) were treated with 0.1 to 100 ng/mL of HGF or KGF for up to 5 days. Cell cultures were assessed for proliferation, migration, and differentiation into myofibroblasts. Organ cultures were used to evaluate the effect of HGF and KGF on reepithelialization following a wound, epithelial morphology and stratification, keratocyte numbers directly beneath the wounded area, and differentiation into myofibroblasts. RESULTS: The 2 growth factors had opposite effects on the rate of reepithelialization, with HGF delaying and KGF accelerating epithelial coverage of the wound. Morphologic assessment showed that both growth factors affected the stratification and differentiation of the epithelium. Both factors stimulated proliferation of keratocytes in serum-free cell culture, although neither induced the appearance of myofibroblasts. This was in contrast to wounded organ cultures treated with 100 ng/mL HGF, in which large numbers of myofibroblasts were observed under the wound. Control corneas and those receiving KGF contained very few myofibroblasts. Keratocyte repopulation of the denuded area under the wound was enhanced in the presence of HGF but decreased in response to KGF. CONCLUSIONS: Hepatocyte growth factor and KGF appeared to have potent and often opposite effects on epithelial and stromal cells following a wound. Hepatocyte growth factor was more detrimental than KGF, resulting in an aberrant epithelium and mass differentiation of keratocytes into myofibroblasts. Inhibition of HGF may be an appropriate therapeutic intervention in the case of persistent epithelial defects and to prevent fibrosis following a corneal stromal wound such as can occur after refractive surgery.

Animals↗

PubMed2004

The photoreactivity of ocular lipofuscin.

Lipofuscin or "age pigment" is a lipid-protein complex which accumulates in a variety of postmitotic, metabolically active cells throughout the body. These complexes, which are thought to result from the incomplete degradation of oxidised substrate, have the potential for photoreactivity. This is particularly so in the retina in which the lipofuscin not only contains retinoid metabolites but is also exposed to high oxygen and fluxes of visible light all of which provide an ideal environment for the generation of reactive oxygen species (ROS). Lipofuscin is a potent photoinducible generator of ROS with the potential to damage proteins, lipids and DNA. Retinal cell dysfunction may be strongly associated with photoreactivity of lipofuscin and may contribute to age-related disease and vision loss.

Eye Diseases↗

PubMed2004

Stem cells in the eye.

In the adult organism, all tissue renewal and regeneration depends ultimately on somatic stem cells, and the eye is no exception. The importance of limbal stem cells in the maintenance of the corneal epithelium has long been recognised, and such cells are now used clinically for repair of a severely damaged cornea. The slow cycling nature of lens epithelial cells and their ability to terminally differentiate into fiber cells are suggestive of a stem cell lineage. Furthermore, recent studies have identified progenitor cells in the retina and ocular vasculature which may have important implications in health and disease. Although the recent literature has become flooded with articles discussing aspects of stem cells in a variety of tissues our understanding of stem cell biology, especially in the eye, remains limited. For instance, there is no definitive marker for ocular stem cells despite a number of claims in the literature, the patterns of stem cell growth and amplification are poorly understood and the microenvironments important for stem cell regulation and differentiation pathways are only now being elucidated. A greater understanding of ocular stem cell biology is essential if the clinical potential for stem cells is to be realised. For instance; How do we treat stem cell deficiencies? How do we use stem cells to regenerate damaged retinal tissue? How do we prevent stem cell lineages contributing to retinal vascular disease? This review will briefly consider the principal stem cells in the mature eye but will focus in depth on limbal stem cells and corneal epithelium. It will further discuss their role in pathology and their potential for therapeutic intervention.

Eye↗

PubMed2004

Expression of placenta growth factor is regulated by both VEGF and hyperglycaemia via VEGFR-2.

Placenta growth factor (PlGF) has been implicated in both physiological and pathological angiogenesis; however, little is known about what regulates its expression. In this study, retinal microvascular endothelial cells and pericytes were exposed to varying concentrations of VEGF and glucose and PlGF expression measured by RT-PCR and Western blotting. Both PlGF mRNA and protein were observed in unstimulated microvascular endothelial cells with only weak expression in pericytes. In endothelial cells, VEGF (100 ng/ml) and glucose (15 mM) induced an increase in expression of PlGF at both the mRNA and protein level while no effect was observed for pericytes. The increase in PlGF expression could be totally abolished by blocking VEGFR-2, and in the case of glucose by neutralising VEGF. VEGF-stimulated PlGF expression was largely inhibited by PD 98059, an inhibitor of mitogen-activated protein kinase (MAPK) and partially by GF 109203X, an inhibitor of protein kinase C (PKC), indicating that VEGF up-regulates PlGF expression via the MAPK signalling pathway and partially through PKC. Taken together, our findings suggest that VEGF orchestrates the contribution of PlGF in angiogenesis via more than one intracellular pathway and that hyperglycaemia, as occurs in diabetes, is an important regulator of PlGF expression via VEGF up-regulation.

Animals↗

PubMed2004

Deferral of the rectal examination in blunt trauma patients: a clinical decision rule.

OBJECTIVES: To develop a clinical decision rule that would allow for the safe deferral of the digital rectal examination (DRE) in blunt trauma patients. METHODS: The authors reviewed the medical records of all adult blunt trauma patients meeting trauma team activation criteria over a 14-month period. The results of the DRE and six predictor variables-abnormal neurologic examination, abdominal tenderness, pelvic stability, blood at the urethral meatus, blood pressure < 90 mm Hg, and age over 65 years-were recorded. Patients with abnormal DREs had their discharge summaries reviewed for specific criteria to determine if the abnormal DRE was a true- or false-positive examination. Predictor variables were entered into a classification and regression tree (CART) analysis designed to predict true-positive abnormal DREs. RESULTS: Of the 579 patients, 53 had abnormal DREs, 34 of which were true positives. CART analysis retained three predictors, abnormal neurologic examination, blood at the urethral meatus, and age over 65 years, and accurately classified all patients with a true-positive abnormal DRE. The probability of a true-positive abnormal DRE in a patient with a normal neurologic examination, no blood at the urethral meatus, and age less than 65 years is between 0% and 0.8%. CONCLUSIONS: Adult patients with blunt trauma and a normal neurologic examination, with no blood at the urethral meatus, and who are less than 65 years old have an exceedingly low likelihood of a true-positive abnormal DRE. If validated, patients who meet these three criteria may have the DRE safely deferred.

Abdominal Injuries↗

PubMed2003

Ageing of the retinal pigment epithelium: implications for transplantation.

This review will discuss some of the implications for using cells from aged donors for retinal pigment epithelium (RPE) transplantation. It will consider age-related changes in the structure and function of RPE cells and the accumulation of potentially damaging photoreactive constituents. The review will focus on the role of the ocular pigments lipofuscin and melanin in respect to age-related changes in composition, photoreactivity and potential role in retinal ageing and age-related macular degeneration. The article concludes by considering the suitability of senescent RPE cells for transplantation and whether such cells can be rejuvenated.

Aging↗

PubMed2003

Activation of vascular endothelial growth factor receptor-1 sustains angiogenesis and Bcl-2 expression via the phosphatidylinositol 3-kinase pathway in endothelial cells.

Vascular insufficiency and retinal ischemia precede many proliferative retinopathies and stimulate secretion of various vasoactive growth factors, including vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). It is unclear, however, how PlGF, which is elevated in proliferative diabetic retinopathy and is a VEGF homolog that binds only to VEGF receptor (VEGFR)-1, promotes pathological angiogenesis. When primary microvascular endothelial cells were grown on collagen gels, PlGF-containing ligands upregulated Bcl-2 expression and stimulated the formation of capillary-like tube networks that were retained for up to 14 days in culture. The inhibition of VEGFR-1 results in a dramatic decrease in the number of capillary connections, indicating that VEGFR-1 ligands promote branching angiogenesis. In contrast, VEGF-induced tube formations and Bcl-2 expression were significantly decreased at the end of this period. Flow cytometry analysis of annexin-V/propidium iodide-stained cells revealed that PlGF and PlGF/VEGF heterodimer inhibited apoptosis in serum-deprived endothelial cells. These two growth factors stimulated a survival signaling pathway phosphatidylinositol 3-kinase (PI3K), as identified by increased Akt phosphorylation and because blocking PI3K signalling by adenovirus-mediated overexpression of wild-type phosphatase and tensin homolog on chromosome 10 (PTEN) disrupted angiogenesis and decreased Bcl-2 expression by PlGF and PlGF/VEGF heterodimer, whereas a dominant-negative PTEN mutant enhanced endothelial sprout formation and Bcl-2 expression. Together, these findings indicate that PlGF-containing ligands contribute to pathological angiogenesis by prolonging cell survival signals and maintaining vascular networks.

Animals↗