Aberrant Growth Of Blood Vessels Research Articles

Role of Anti Angiogenic Therapy in Prevention of Recurrence in Hormonal Positive Breast Cancer: A Secondary Prevention Strategy and Method of Therapy

Existing literature supports the role of signaling protein vascular endothelial growth factor (VEGF) in tumor growth and metastasis and furthers its involvement in recurrence. In both experimental and clinical studies, VEGF has been shown to be a significant factor involved for aberrant blood vessel growth, and in fact is the target of several classes of antineoplastic drugs [1] [2] [3] [4]. That said, the current standard of care for estrogen receptor positive breast cancer (although improved over the last decade), has not provided a “meaningful preventive shift” since the discovery of angiogenesis and its role in induction of recurrence. In this article, we discuss an anti angiogenic therapy implementing natural compounds to inhibit the production of VEGF. We applied our preclinical data to justify the predicted effect on VEGF. We used liquid biopsy to monitor patients response to therapy as a surrogate for recurrence. We hypothesize that by inhibition of angiogenesis through this protocol, we are able to positively impact tumor recurrence. It is our experience that patients in our sample even with high recurrence scores (based on Oncotype Dx testing) had a major reduction in recurrence when estrogen blockers were combined with this protocol. We also propose longitudinal studies to compare outcomes with combinational therapies with estrogen blockers in highly expected to recur disease.

Nanocarriers for Treatment of Ocular Neovascularization in the Back of the Eye: New Vehicles for Ophthalmic Drug Delivery

Pathologic neovascularization of the retina is a major cause of substantial and irreversible loss of vision. Drugs are difficult to deliver to the lesions in the back of the eye and this is a major obstacle for the therapeutics. Current pharmacological approach involves an intravitreal injection of anti-VEGF agents to prevent aberrant growth of blood vessels, but it has limitations including therapeutic efficacy and side-effects associated with systemic exposure and invasive surgery. Nanotechnology provides novel opportunities to overcome the limitations of conventional delivery system to reach the back of the eye through fabrication of nanostructures capable of encapsulating and delivering small molecules. This review article introduces various forms of nanocarrier that can be adopted by ocular drug delivery systems to improve current therapy. The application of nanotechnology in medicine brings new hope for ocular drug delivery in the back of the eye to manage the major causes of blindness associated with ocular neovascularization.

The unfolded protein response in retinal vascular diseases: implications and therapeutic potential beyond protein folding.

Angiogenesis is a complex, step-wise process of new vessel formation that is involved in both normal embryonic development as well as postnatal pathological processes, such as cancer, cardiovascular disease, and diabetes. Aberrant blood vessel growth, also known as neovascularization, in the retina and the choroid is a major cause of vision loss in severe eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, and central and branch retinal vein occlusion. Yet, retinal neovascularization is causally and dynamically associated with vasodegeneration, ischemia, and vascular remodeling in retinal tissues. Understanding the mechanisms of retinal neovascularization is an urgent unmet need for developing new treatments for these devastating diseases. Accumulating evidence suggests a vital role for the unfolded protein response (UPR) in regulation of angiogenesis, in part through coordinating the secretion of pro-angiogenic growth factors, such as VEGF, and modulating endothelial cell survival and activity. Herein, we summarize current research in the context of endoplasmic reticulum (ER) stress and UPR signaling in retinal angiogenesis and vascular remodeling, highlighting potential implications of targeting these stress response pathways in the prevention and treatment of retinal vascular diseases that result in visual deficits and blindness.

The anti-angiogenic role of discoidin domain receptor 2 (DDR2) in laser-induced choroidal neovascularization.

Choroidal neovascularization (CNV), an aberrant growth of blood vessels in the choroid layer of the eye, is a major cause of vision loss. In view of our recent finding that discoidin domain receptor 2 (DDR2), a collagen-binding receptor tyrosine kinase, is involved in control of vascular endothelial activity and tumor angiogenesis, the present study aims to investigate whether and how DDR2 affects the pathogenesis of CNV. We initially found that a spontaneous DDR2 mutant mouse colony (slie) exhibited enhanced amplitude of laser-induced CNV. The inhibitory role of DDR2 in CNV development was further confirmed by experiments through intravitreous injection of DDR2 small interference RNA (siRNA) or DDR2-expressing adenovirus. Quantitative real-time polymerase chain reaction (qPCR) and immunoblot analysis showed that DDR2 regulates the expression of several major pro-angiogenic factors in the laser-injured choroid as well as in retinal pigment epithelium (RPE) cells. In addition, it was demonstrated that the CNV-induced increases in the phosphorylation levels of Akt and mTOR were affected by the upregulation or downregulation of DDR2. Thus, the data from this study for the first time revealed that DDR2 negatively regulates the development of experimental CNV in vivo, which may provide a novel target for preventing human pathological ocular neovascularization. Key messages: DDR2 does not affect retinal development. DDR2 inhibits laser-induced CNV. DDR2 regulates angiogenic factor expression in CNV lesion as well as in RPE cells. DDR2 is involved in modulation of CNV-induced activation of PI3K pathway.

Prostate Specific Membrane Antigen (PSMA) Regulates Angiogenesis Independently of VEGF during Ocular Neovascularization

BackgroundAberrant growth of blood vessels in the eye forms the basis of many incapacitating diseases and currently the majority of patients respond to anti-angiogenic therapies based on blocking the principal angiogenic growth factor, vascular endothelial growth factor (VEGF). While highly successful, new therapeutic targets are critical for the increasing number of individuals susceptible to retina-related pathologies in our increasingly aging population. Prostate specific membrane antigen (PSMA) is a cell surface peptidase that is absent on normal tissue vasculature but is highly expressed on the neovasculature of most solid tumors, where we have previously shown to regulate angiogenic endothelial cell invasion. Because pathologic angiogenic responses are often triggered by distinct signals, we sought to determine if PSMA also contributes to the pathologic angiogenesis provoked by hypoxia of the retina, which underlies many debilitating retinopathies.Methodology/Principal FindingsUsing a mouse model of oxygen-induced retinopathy, we found that while developmental angiogenesis is normal in PSMA null mice, hypoxic challenge resulted in decreased retinal vascular pathology when compared to wild type mice as assessed by avascular area and numbers of vascular tufts/glomeruli. The vessels formed in the PSMA null mice were more organized and highly perfused, suggesting a more ‘normal’ phenotype. Importantly, the decrease in angiogenesis was not due to an impaired hypoxic response as levels of pro-angiogenic factors are comparable; indicating that PSMA regulation of angiogenesis is independent of VEGF. Furthermore, both systemic and intravitreal administration of a PSMA inhibitor in wild type mice undergoing OIR mimicked the PSMA null phenotype resulting in improved retinal vasculature.Conclusions/SignificanceOur data indicate that PSMA plays a VEGF-independent role in retinal angiogenesis and that the lack of or inhibition of PSMA may represent a novel therapeutic strategy for treatment of angiogenesis-based ocular diseases.

The significance of neuronal and glial cell changes in the rat retina during oxygen-induced retinopathy

Retinopathy of prematurity is a devastating vascular disease of premature infants. A number of studies indicate that retinal function is affected in this disease. Using the rat model of oxygen-induced retinopathy, it is possible to explore more fully the complex relationship between neuronal, glial and vascular pathology in this condition. This review examines the structural and functional changes that occur in the rat retina following oxygen-induced retinopathy. We highlight that vascular pathology in rats is characterized by aberrant growth of blood vessels into the vitreous at the expense of blood vessel growth into the body of the retina. Moreover, amino acid neurochemistry, a tool for examining neuronal changes in a spatially complete manner reveals widespread changes in amacrine and bipolar cells. In addition, neurochemical anomalies within inner retinal neurons are highly correlated with the absence of retinal vessels. The key cell types that link blood flow with neuronal function are macroglia. Macroglia cells, which in the retina include astrocytes and Müller cells, are affected by oxygen-induced retinopathy. Astrocyte loss occurs in the peripheral retina, while Müller cells show signs of reactive gliosis that is highly localized to regions that are devoid of intraretinal blood vessels. Finally, we propose that treatments, such as blockade of the renin-angiotensin system, that not only targets pathological angiogenesis, but that also promotes re-vascularization of the retina are likely to prove important in the treatment of those with retinopathy of prematurity.

Current and Emerging Concepts in the Management of Neovascular Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly worldwide. The more severe form of the disease, known as neovascular AMD, is characterized by aberrant growth of blood vessels from the choroid into the subretinal space. This pathologic choroidal neovascularization can have drastic consequences, often seriously impairing vision in affected individuals. Current treatment approaches focus on combination therapies that include photodynamic therapy in conjunction with numerous forms of antiangiogenic or anti-inflammatory drug intervention. To date, however, no adequate treatment is available for the majority of affected individuals. The threat of a rapidly aging population provides the impetus for aggressive efforts to control the prevalence and progression of this disease. This review will outline the currently available pharmacotherapies, discussing the justification for their use as well as their shortcomings. Furthermore, drugs that are currently under investigation as monotherapies and adjuncts will be highlighted. The potential for alternate targets will also be examined, with a focus on the most promising candidates.

Three-Dimensional In Vivo Imaging of the Mouse Intraocular Vasculature during Development and Disease

Aberrant growth of blood vessels in the eye is a major cause of vision loss, occurring as a complication of diabetic retinopathy, age-related macular degeneration, and retinal vascular occlusions, among others. Whereas in humans, in vivo angiography is routinely used to image such diseases, many animal models of ocular vascular disease and development rely on dissected tissues that may not accurately represent in vivo conditions and require enucleation of the eye, the death of the animal, or both. A method of three-dimensional imaging of blood vessels was used in the living mouse eye that involved scanning laser confocal microscopy and computer-aided image reconstruction. This minimally invasive technique was used to collect three-dimensional images of intraocular vessels in vivo during development. The retinal and choroidal vasculature was studied during development and disease, in models of retinal degeneration, central retinal vein occlusion, and oxygen-induced retinopathy. To aid in investigations into cell-based therapies for retinal disease, two-color imaging was used to localize transplanted cells in relation to the vasculature. This technique was used to perform serial imaging of the ocular vasculature over time, when developmental regression of vessels was observed. This in vivo vascular imaging approach is valuable in monitoring normal development, disease progression, and efficacy of experimental treatments in mouse models of ocular vascular disease and may have broader applications to the field of angiogenesis by using the readily visualized ocular vascular bed as a surrogate to test pro- and antiangiogenic compounds.

Pigment-epithelium-derived factor (PEDF) occurs at a physiologically relevant concentration in human blood: purification and characterization.

Pigment epithelium-derived factor (PEDF) inhibits the formation of blood vessels in the eye by inducing apotosis in actively dividing endothelial cells. The activity of PEDF equals or supersedes that of other anti-angiogenic factors, including angiostatin, endostatin and thrombospondin-1. In addition, PEDF has the potential to promote the survival of neurons and affect their differentiation. Here we show that PEDF is present in plasma at a concentration of approx. 100 nM (5 microg/ml) or twice the level required to inhibit aberrant blood-vessel growth in the eye. Thus the systemic delivery of PEDF has the potential to affect angiogenesis or neurotrophic processes throughout the body, significantly expanding the putative physiological role of the protein. A complete map of all post-translational modifications revealed that authentic plasma PEDF carries an N-terminal pyroglutamate blocking group and an N-linked glycan at position Asn266. The pyroglutamate residue may regulate the activity of PEDF analogously to the manner in which it regulates thyrotropin-releasing hormone.

Prevention of ischemia-induced retinopathy by the natural ocular antiangiogenic agent pigment epithelium-derived factor.

Aberrant blood vessel growth in the retina that underlies the pathology of proliferative diabetic retinopathy and retinopathy of prematurity is the result of the ischemia-driven disruption of the normally antiangiogenic environment of the retina. In this study, we show that a potent inhibitor of angiogenesis found naturally in the normal eye, pigment epithelium-derived growth factor (PEDF), inhibits such aberrant blood vessel growth in a murine model of ischemia-induced retinopathy. Inhibition was proportional to dose and systemic delivery of recombinant protein at daily doses as low as 2.2 mg/kg could prevent aberrant endothelial cells from crossing the inner limiting membrane. PEDF appeared to inhibit angiogenesis by causing apoptosis of activated endothelial cells, because it induced apoptosis in cultured endothelial cells and an 8-fold increase in apoptotic endothelial cells could be detected in situ when the ischemic retinas of PEDF-treated animals were compared with vehicle-treated controls. The ability of low doses of PEDF to curtail aberrant growth of ocular endothelial cells without overt harm to retinal morphology suggests that this natural protein may be beneficial in the treatment of a variety of retinal vasculopathies.