R-Ras Deficiency in Pericytes Causes Frequent Microphthalmia and Perturbs Retinal Vascular Development

2021 ◽  
pp. 1-15
Author(s):  
Jose Luis Herrera ◽  
Masanobu Komatsu
Keyword(s):  
Vascular Development ◽  
Small Gtpase ◽  
Endothelial Cell Proliferation ◽  
Retinal Vasculature ◽  
Blood Vessel Wall ◽  
Blood Retinal Barrier ◽  
Pericyte Coverage ◽  
Capillary Plexus ◽  
Plasma Leakage ◽  
Specific Contribution

<b><i>Purpose:</i></b> The retinal vasculature is heavily invested by pericytes. Small GTPase R-Ras is highly expressed in endothelial cells and pericytes, suggesting importance of this Ras homolog for the regulation of the blood vessel wall. We investigated the specific contribution of pericyte-expressed R-Ras to the development of the retinal vasculature. <b><i>Methods:</i></b> The effect of R-Ras deficiency in pericytes was analyzed in pericyte-targeted conditional <i>Rras</i> knockout mice at birth and during the capillary plexus formation in the neonatal retina. <b><i>Results:</i></b> The offspring of these mice frequently exhibited unilateral microphthalmia. Analyses of the developing retinal vasculature in the eyes without microphthalmia revealed excessive endothelial cell proliferation, sprouting, and branching of the capillary plexus in these animals. These vessels were structurally defective with diminished pericyte coverage and basement membrane formation. Furthermore, these vessels showed reduced VE-cadherin staining and significantly elevated plasma leakage indicating the breakdown of the blood-retinal barrier. This defect was associated with considerable macrophage infiltration in the retina. <b><i>Conclusions:</i></b> The normal retinal vascular development is dependent on R-Ras expression in pericytes, and the absence of it leads to unattenuated angiogenesis and significantly weakens the blood-retinal barrier. Our findings underscore the importance of R-Ras for pericyte function during the normal eye development.

The Use of Multidimensional Microscopy in the Characterization of Retinal Vascular Development in a Murine Model

2001 ◽  
Vol 7 (S2) ◽  
pp. 1010-1011
Author(s):  
Robert G. Summers ◽  
Edith Aguilar ◽  
Marilyn Leonard ◽  
Martin Friedlander
Keyword(s):  
Collagen Type ◽  
Vascular Development ◽  
Multiphoton Microscopy ◽  
Vascular Diseases ◽  
Collagen Type Iv ◽  
Retinal Vasculature ◽  
3 Dimensional ◽  
Type Iv ◽  
Developing System

The murine retinal vasculature develops in its entirety following birth through the process of angiogenesis. This developing system provides an extremely accessible model for investigation of angiogenic mechanisms in general and as they pertain to vascular diseases of the eye (e.g. diabetic retinopathy and macular degeneration). The model is particularly relevant clinically because the developmental events of retinal vascularization are nearly identical in mice and humans, although primate vessels develop in utero during the final trimester of pregnancy and are thus less accessible for experimental study. The model is also excellent for the testing of anti-angiogenic agents as potential treatments for vascular diseases. in this report we outline the use of confocal optical microscopy and multiphoton microscopy in the 3-dimensional characterization of retinal vascular development in the mouse.We employed confocal microscopy to characterize the events of vascular development from postnatal days 0-56 (P0-P56). During this time the retinas are transformed from simple, thin bilaminar structures to more complex, functional, adult sensory organs. Retinal morphogenesis continues until P42. Retinas were dissected from eyes and vessels stained with collagen type-IV antibody (1) or Bandeiraea simplicifolia (Griffonia) lectin-dye conjugate (2) to outline the blood vessels. All patent vessels were stained by both techniques.

scholarly journals Human endometrial angiogenesis

Reproduction ◽  
2001 ◽  
pp. 181-186 ◽  
Author(s):  
CE Gargett ◽  
PA Rogers
Keyword(s):  
Strong Relationship ◽  
Human Endometrium ◽  
Endothelial Cell Proliferation ◽  
Microvascular Endothelial Cells ◽  
Vascular Endothelial ◽  
Proliferative Phase ◽  
Vessel Growth ◽  
Capillary Plexus ◽  
Reproductive Life ◽  
Endothelial Growth Factor

Angiogenesis is the development of new microvessels from existing vessels, a process that involves microvascular endothelial cells. Physiological angiogenesis rarely occurs in adults except in the ovary and endometrium during the reproductive life of females. Angiogenesis occurs by sprouting and non-sprouting mechanisms. Since endothelial sprouts are not observed in human endometrium, we hypothesized that non-sprouting mechanisms such as intussusception and elongation are involved in endometrial angiogenesis. The demand for angiogenesis differs spatially and temporally in the endometrium: angiogenesis occurs in the basalis layer during menstruation and in the functionalis and subepithelial capillary plexus during the proliferative and early secretory stages. Most studies have failed to demonstrate a link between expression of endometrial angiogenic factors and new vessel growth. However, we demonstrated recently a strong relationship between vascular endothelial growth factor (VEGF) immunolocalized in in-travascular neutrophils and endothelial cell proliferation in each of the subepithelial capillary plexus, functionalis and basalis regions of the human endometrium. Our data also indicate that focal neutrophil VEGF has a role in the development of the subepithelial capillary plexus and functionalis microvessels during the proliferative phase of the menstrual cycle. We propose that neutrophils are an intravascular source of VEGF for vessels that undergo angiogenesis by intussusception and elongation.

scholarly journals Perturbed Biochemical Pathways and Associated Oxidative Stress Lead to Vascular Dysfunctions in Diabetic Retinopathy

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Nidhi Mahajan ◽  
Palkin Arora ◽  
Rajat Sandhir
Keyword(s):  
Oxidative Stress ◽  
Diabetic Retinopathy ◽  
Protein Function ◽  
Treatment Strategies ◽  
Renin Angiotensin System ◽  
Redox Status ◽  
Metabolic Memory ◽  
Retinal Vasculature ◽  
Blood Retinal Barrier ◽  
Biochemical Pathways

Diabetic retinopathy (DR) is a vascular insult that accompanies the hyperglycemic state. Retinal vasculature holds a pivotal role in maintaining the integrity of the retina, and any alteration to retinal vasculature affects retinal functions. The blood retinal barrier, a prerequisite to vision acuity, is most susceptible to damage during the progression of DR. This is a consequence of impaired biochemical pathways such as the polyol, advanced end glycation products (AGE), hexosamine, protein kinase C (PKC), and tissue renin-angiotensin system (RAS) pathways. Moreover, the role of histone modification and altered miRNA expression is also emerging as a major contributor. Epigenetic changes create a link between altered protein function and redox status of retinal cells, creating a state of metabolic memory. Although various biochemical pathways underlie the etiology of DR, the major insult to the retina is due to oxidative stress, a unifying factor of altered biochemical pathways. This review primarily focuses on the critical biochemical pathways altered in DR leading to vascular dysfunctions and discusses antioxidants as plausible treatment strategies.

μ Opioid Receptor Stimulates a Growth Promoting and Pro-Angiogenic Tumor Microenvironment by Transactivating VEGF Receptor-2/Flk-1.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3687-3687
Author(s):  
Elliot J. Stephenson ◽  
Humberto J. Martinez-Suarez ◽  
Mariya Farooqui ◽  
Debabrata Mukhopadhyay ◽  
Deborah A. Hughes ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Tumor Growth ◽  
Opioid Receptor ◽  
Calcium Release ◽  
Small Gtpase ◽  
Endothelial Cell Proliferation ◽  
Vegf Receptor ◽  
Growth Promoting ◽  
Stimulation Of

Abstract Like VEGF, morphine stimulates MAPK/ERK and Akt, leading to the promotion of angiogenesis via NO dependent signaling (Cancer Res62: 4491, 2002). Morphine acts via pertussis toxin (PT)-dependent G-protein coupled receptors (GPCRS), while VEGF acts via receptor tyrosine kinases (RTKs). We showed that PT-dependent GPCRs transactivate VEGF receptor-2/Flk1 via small GTPase RhoA (JBC277: 4679, 2002; JBC278:20738, 2003). Therefore, we hypothesized that morphine via the mu opioid receptor (MOR) transactivates Flk1 and promotes a pro-angiogenic microenvironment. Morphine-induced proliferation of human umbilical vein endothelial cells (HUVEC) was completely abrogated by Y-27632 (100 μM), a highly selective and potent inhibitor of Rho-associated protein kinases, suggesting the activation of Rho signaling by morphine. Addition of 1 μM morphine potentiated VEGF-induced (10 ng/ml) proliferation of HUVEC by 25%. We observed a 30% increase in intracellular calcium release after VEGF stimulation of HUVEC pre-incubated with morphine as compared to HUVEC pre-incubated with PBS, detected by a change in the fluorescence ratio of the Fura-2 AM dye. These findings show that morphine, via MOR and Rho signaling, transactivates Flk1 leading to the stimulation of calcium signaling and endothelial cell proliferation. To functionally corroborate our hypothesis, we used MOR knockout (MOR-KO) mice and injected them with MOR-replete T241 fibrosarcoma cells. T241 fibrosarcoma tumor growth in vivo showed appearance of palpable and measurable tumors 2 days earlier in wild type (wt) as compared to MOR-KO mice. Tumor growth and angiogenesis were decreased by 20–35% in MOR-KO mice as compared to wt littermates during 3 weeks of tumor growth. None of the MOR-KO showed signs of lung metastasis versus 40% wt mice with metastasis. Morphine (1.42 for the first 2 wks and 2.14 mg/Kg/day later, respectively) stimulated 20–35% tumor growth in wt, but not in MOR-KO mice. Western immunoblotting showed a 10-fold increase in the expression of phospho-Flk1 in morphine treated wt tumors as compared to PBS-treated wt mice. Morphine did not stimulate phospho-Flk1 expression in MOR-KO mice. Western analysis of immunoprecipitates obtained with α-MOR antibody showed the expression of Flk1 and phospho-Flk1 in wt, but were not expressed in MOR-KO tumors. Thus, MOR stimulates the transactivation of Flk1 in wt mice but not in MOR-KO. These in vitro and in vivo data using MOR-KO mice and the MOR agonist, morphine, show that MOR stimulates endothelial proliferation, angiogenesis and promotes tumor growth and metastasis directly as well as by transactivating Flk1 phosphorylation. We speculate that MOR is a critical component of the ‘angiogenic switch’, which regulates the pro-angiogenic and growth promoting tumor microenvironment. Thus, MOR provides a novel target for developing anti-angiogenic therapies.

scholarly journals Assessment of the retinal vasculature in healthy Chinese preschool children aged 4–6 years old using optical coherence tomography angiography

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lu Xiang ◽  
Yingming Zhou ◽  
Yanwei Chen ◽  
Siyu Jiang ◽  
Chunli Fei ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Preschool Children ◽  
Optic Disc ◽  
Optical Coherence Tomography Angiography ◽  
Vessel Density ◽  
Retinal Vasculature ◽  
Optical Coherence ◽  
Significant Difference ◽  
Capillary Plexus ◽  
The Mean

Abstract Purpose To establish normal parameters of macular and optic disc vasculature by optical coherence tomography angiography (OCTA) in healthy preschool children aged 4–6 years old in China. OCTA reflects retinal metabolism and development in children at these ages and could be used clinically and in future studies to aid diagnosis and prediction of retinal abnormalities and developmental stagnation. Methods In this cross-sectional study, we measured foveal, parafoveal, and perifoveal vessel density in the superficial capillary plexus (SCP); the deep capillary plexus (DCP), the foveal avascular zone (FAZ), and the radial capillary peripapillary (RPC) in the optic disc using investigational spectral-domain OCTA. The magnification effect of the FAZ area and microvasculature measurements was corrected by Littman and the modified Bennett formula. Results A total of 242 eyes (116 males and 126 females, 5.31 ± 0.73 years) were recruited for the analysis. The mean macular vessel density was 48.10 ± 2.92% and 48.74 ± 6.51% in the SCP and the DCP, respectively. The RPC vessel density was 47.17 ± 2.52%, 47.99 ± 4.48%, and 48.41 ± 3.07% in the whole image, inside disc, and peripapillary, respectively; and the mean FAZ area was 0.28 ± 0.11 mm2. A significant difference between male and female participants was found in the retinal vasculature (DCP, SCP, and RPC). None of these parameters were significantly different in age (P > 0.05), except that DCP slightly increased with aging. The right and left eyes had good consistency in the parameters of the macula and optic disc. Conclusions Our study establishes the macular and optic disc OCTA reference values in 4- to 6-year-old healthy preschool children. They may be used in longitudinal OCTA studies and clinical applications.

Abstract 16948: A Comprehensive and High Accurate Pipeline for Mouse Retinal Vasculature Characterization

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Xuelin Wang ◽  
Shumin Wang ◽  
Guofu Zhu ◽  
Jordan Rhen ◽  
Jinjiang Pang ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Vascular Development ◽  
Vascular Diseases ◽  
High Accuracy ◽  
Pathological Process ◽  
Retinal Vasculature ◽  
Microvascular Remodeling ◽  
Vessel Network ◽  
Isolectin B4 ◽  
Global And Local

Rationale: Vascular morphological features reflect the vessel biological functions and analysis of these features is critical for understanding physiological and pathological process of vascular development and vascular diseases. Mouse retinal vasculature is a well-recognized and commonly used animal model for angiogenesis and microvascular remodeling. Thus, a powerful tool to analyze morphological changes of retinal vasculature is in urgent need. Objective: Develop a comprehensive and high accurate pipeline to analyze morphological changes of mouse retinal vasculature. Methods and Results: Retinas from postnatal mice at P2-P7 are harvested and retinal vasculatures are visualized by isolectin B4 whole mount staining. A comprehensive software, Vessel Tech, is developed to perform vessel segmentation, network reconstruction and analysis. Vessel Tech relies on recent advancements in the convolutional neural network and techniques from network data analysis to provide high accuracy vascular identification and comprehensive vascular morphological feature extraction. Compared with existing blood vessel analysis softwares, Vessel Tech shows great improvement in accuracy. Based on the reconstructed vessel network, various metrics of angiogenesis and micro-remodeling are extracted and statistically analyzed. Conclusions: We generated and verified a novel pipeline, named “Vessel Tech”, which could automatically process retinal vascular images, reconstruct vessel network with high accuracy and assay global and local vascular characteristics. The development of Vessel Tech provides a powerful tool to precisely study the physiological and pathological variations during vascular development and vascular diseases.

Mouse Wnt receptor gene Fzd5 is essential for yolk sac and placental angiogenesis

Development ◽  
2001 ◽  
Vol 128 (1) ◽  
pp. 25-33 ◽  
Author(s):  
T. Ishikawa ◽  
Y. Tamai ◽  
A.M. Zorn ◽  
H. Yoshida ◽  
M.F. Seldin ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Receptor Gene ◽  
Embryonic Stem ◽  
Yolk Sac ◽  
Endothelial Cell Proliferation ◽  
Placental Angiogenesis ◽  
Homozygous Mutant ◽  
Wnt Ligands ◽  
Capillary Plexus ◽  
Brdu Labeling

Wnts are secreted signaling molecules implicated in various developmental processes and frizzled proteins are the receptors for these Wnt ligands. To investigate the physiological roles of frizzled proteins, we isolated and characterized a novel mouse frizzled gene Fzd5. Fzd5 mRNA was expressed in the yolk sac, eye and lung bud at 9.5 days post coitum. Fzd5 specifically synergized with Wnt2, Wnt5a and Wnt10b in ectopic axis induction assays in Xenopus embryos. Using homologous recombination in embryonic stem cells, we have generated Fzd5 knockout mice. While the heterozygotes were viable, fertile and appeared normal, the homozygous embryos died in utero around 10.75 days post coitum, owing to defects in yolk sac angiogenesis. At 10.25 days post coitum, prior to any morphological changes, endothelial cell proliferation was markedly reduced in homozygous mutant yolk sacs, as measured by BrdU labeling. By 10.75 days post coitum, large vitelline vessels were poorly developed, and the capillary plexus was disorganized. At this stage, vasculogenesis in the placenta was also defective, although that in the embryo proper was normal. Because Wnt5a and Wnt10b co-localized with Fzd5 in the developing yolk sac, these two Wnts are likely physiological ligands for the Fzd5-dependent signaling for endothelial growth in the yolk sac.

scholarly journals Retinal Vasculature and Microstructure in Early Dry-Type Myopic Maculopathy

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Jiao Sun ◽  
Jialin Wang ◽  
Yanling Wang
Keyword(s):  
Logistic Regression ◽  
Refractive Error ◽  
Choroidal Thickness ◽  
Retinal Vessel ◽  
Vessel Density ◽  
Retinal Vasculature ◽  
Capillary Plexus ◽  
Group 2 ◽  
Myopic Maculopathy ◽  
Group 1

Purpose. The aim of this cross-sectional study was to characterize and compare the retinal vasculature and microstructure in patients with early dry-type myopic maculopathy. Methods. Patients with a refractive error of less than −6 diopters were enrolled and classified into two groups. Group 1 comprised 82 eyes with a tessellated fundus, and group 2 comprised 56 eyes with diffuse chorioretinal atrophy (DCA). The clinical characteristics, refractive error, axial length, retinal vessel density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), macular choroidal thickness, and best-corrected visual acuity (BCVA), were compared between the groups. Logistic regression was used to determine the protective and risk factors for DCA. Results. Group 1 patients were significantly younger and had better BCVA, less myopia, and shorter axial length than group 2 patients. The vessel densities of the SCP and DCP, choroidal thickness, retinal nerve fiber layer thickness, ganglion cell complex thickness, and retinal thickness were reduced in group 2. Multiple logistic regression analysis revealed that the vessel densities of the SCP and DCP were protective factors for DCA. Conclusions. The vessel density of the SCP had the highest diagnostic value (sensitivity = 78.0% and specificity = 96.6%). When the SCP vessel density was reduced to ≤49.98%, DCA was indicated. The retinal vessel densities of the SCP and DCP and parameters of the microstructure were reduced significantly in patients with DCA. Vessel density may be a better diagnostic indicator of the development of DCA.

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