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Results for “Neovascularization, Physiologic”

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At least 19 recordsLinked to original sources
PubMed1989

[Intraocular pressure during vitrectomy in the diabetic patient].

23 eyes underwent vitrectomy for diabetic proliferative retinopathy complications: vitreous hemorrhage with or without tractional retinal detachment. After 6 months of follow-up, 64% of eyes had final visual acuities of 1/40 or better. Preoperative iris neovascularization and preoperative detachment of the macula have a worse prognosis. Decrease of peroperative complications is allowed by checking of intraocular pressure during vitrectomy.

Adolescent↗
PubMed2025

Zonal endothelial cell heterogeneity underlies murine renal vascular development.

The renal vasculature consists of highly specialized blood vessels with distinct physiological functions. Defining their transcriptional signatures and tracing their developmental ontogeny has thus far been challenging due to a lack of regionally specific endothelial biomarkers. Here, we performed single nuclear RNA sequencing (snucRNA-Seq) to interrogate the transcriptional heterogeneity of embryonic renal endothelial cells (ECs). We identified ten endothelial subtypes, and validated regionally restricted expression of novel marker genes of glomeruli, arteries, vasa recta, and immature capillary subtypes using multiplex RNAscope. We also define previously uncharacterized and heterogeneous molecular signatures of the immature renal vasculature, including putative endothelial progenitors. We interrogate biological characteristics of immature EC types using a variety of in vivo tools. Lineage tracing of Esm1-expressing cells reveals the previously unrecognized multi-origin and multi-clonal endothelial tip cell contribution to the glomerular vasculature. Together, this study provides a validated, tool-focused developmental atlas of the murine renal vasculature and elucidates novel cellular mechanisms of nephron vascularization.

Animals↗
PubMed2026

Hypoxia-activated scleraxis a mediates epicardial progenitor differentiation into a unique cardiac perivascular cell type.

The epicardium provides progenitor cells and paracrine signals essential for heart development and regeneration, yet the mechanisms regulating epicardial cell fate remain poorly understood. Here, we identify the transcription factor Scleraxis a (scxa) as a key regulator of epicardial progenitor differentiation in zebrafish. Single-cell transcriptomics, genetic lineage tracing, and cardiac injury models reveal transient scxa expression in activated epicardial progenitor cells (aEPCs) during developmental coronary angiogenesis and heart regeneration. scxa+ epicardial cells predominantly differentiate into a previously uncharacterized col18a1a+ perivascular population, termed epicardial-derived perivascular mesenchymal cells (Epi-PMCs), which is distinct from pericytes, vascular smooth muscle cells, and mammalian adventitial fibroblasts. Epi-PMCs closely associate with coronary vessels and may contribute to vascular stabilization and remodeling, potentially through collagen XVIII. Loss of scxa increases coronary vessel density. Hypoxia and Hif signaling induce scxa expression, identifying a hypoxia-responsive mechanism that promotes epicardial differentiation toward a vascular-supportive fate during heart development and regeneration.

Animals↗
PubMed2025

Self-organization of sinusoidal vessels in pluripotent stem cell-derived human liver bud organoids.

The induction of tissue-specific vessels in in vitro living tissue systems remains challenging. Here, we directly differentiated human pluripotent stem cells into CD32b+ putative liver sinusoidal progenitors by dictating developmental pathways. By devising an inverted multilayered air-liquid interface culture, hepatic endoderm, septum mesenchyme, arterial and sinusoidal quadruple progenitors self-organize to generate and sustain hepatocyte-like cells neighboured by divergent endothelial subsets composed of CD32blowCD31high, LYVE1+STAB1+CD32bhighCD31lowTHBD-vWF- and LYVE1-THBD+vWF+ cells. WNT2 mediates sinusoidal-to-hepatic intercellular crosstalk potentiating hepatocyte differentiation and branched endothelial network formation. Intravital imaging reveals the iPS-cell-derived putative liver sinusoidal endothelial progenitor develops fully perfused human vessels with functional sinusoid-like features. Organoid-derived hepatocyte- and sinusoid-derived coagulation factors enable correction of in vitro clotting time with Factor V-, VIII-, IX- and XI-deficient plasma, and rescues the severe bleeding phenotype in haemophilia A mice on transplantation. Advanced organoid vascularization technology allows for interrogating key insights governing organ-specific vessel development, paving the way for coagulation disorder therapeutics.

Humans↗
PubMed2025

Rapidly decellularized adipose tissue induces soft tissue vascularization in potential anatomical spaces.

Decellularized tissues provide biological cues owing to the wealth of structural and regulatory factors that promote angiogenesis, adipogenesis, and myogenesis and facilitate neurite outgrowth. Here, we demonstrated the advantages of decellularized adipose tissue (adipoECM) over defined collagen-based biomaterials for host tissue integration. Three batches of human adipose tissue were decellularized using a rapid decellularization protocol and analyzed using mass spectrometry. To assess the biological activity of the decellularized materials, adipoECM and a reference standard of care biomaterial (Integra®DRT, also containing collagen I and glycosaminoglycans) were implanted subcutaneously, but far from the wound bed (in anatomical potential spaces) of immunocompetent BALB/c mice. The mice were euthanized in the acute (1 day) and chronic (day 60) inflammatory reaction phases, followed by biomaterial excision and Masson’s trichrome immunohistofluorescence imaging of the paraffin-embedded specimens. Each batch of processed tissue passed a quality control check, showing a low level of donor genomic DNA, lack of nuclei, lipids, endotoxins, and bacterial contamination. Mass spectrometry revealed that all batches of decellularized tissue mainly contained collagen I and, to a lesser degree, collagen III, collagen IV, collagen V, laminin, fibrillin, fibronectin, tenascin, and elastin. No acute inflammatory reaction was observed in either material one day post-transplantation. At 60 days post-implantation, different cell types were detected in adipoECM specimens, whereas Integra®DRT remained acellular. Additional immunohistochemical staining of adipoECM revealed CD31-positive cells in the blood vessels. Mesenchymal (CD90 positive) and myeloid (CD14 positive) cells were also detected. Primary cell types involved in soft tissue healing and remodeling were found in the adipoECM-treated group. The ingrowth of blood vessels and mesenchymal cells confirmed the effective integration of adipoECM with host tissues. Our results demonstrate that decellularized adipose tissue implanted away from the wound bed possesses contextual biological activities that promote efficient integration with host tissues.

Adipose Tissue↗
PubMed2025

A model of Notch signalling control of angiogenesis: Evidence of a role for Notch ligand heterodimerization.

The ubiquitous Notch receptor signalling network is essential for tissue growth and maintenance. Operationally, receptor activity is regulated by two principal, counterposed mechanisms: intercellular Notch transactivation triggered by interactions between receptors and ligands expressed in neighbouring cells; intracellular cis inhibition mediated by ligands binding to receptors expressed in the same cell. Moreover, different Notch receptor/ligand combinations are known to elicit distinct molecular and cellular responses, and together, these phenomena determine the strength, the duration and the specificity of Notch receptor signalling. To date, it has been assumed that these processes involve discrete ligand homomers and not heteromeric complexes composed of more than one ligand species. In this study, we explore the molecular basis of the opposing actions of the Notch ligands, DLL4 and JAG1, which control angiogenic sprouting. Through a combination of experimental approaches and mathematical modelling, we provide evidence that two mechanisms could underpin this process: 1) DLL4 rather than JAG1 induces efficient Notch1 receptor transactivation; 2) JAG1 directly blocks DLL4-dependent cis-inhibition of Notch signalling through the formation of a JAG1/DLL4 complex. We propose a new model of Notch signalling that recapitulates the formation of tip and stalk cells, which is necessary for sprouting angiogenesis.

Signal Transduction↗
PubMed1992

[Selective occlusion of ocular neovascularization by photodynamic therapy].

Photodynamic therapy (PDT) has successfully been used to induce vascular occlusion via endothelial damage and subsequent thrombosis. To increase the selective of this method for neovascularizations, characteristics in the ultrastructure of the proliferative vessel wall allow physiological vessels to be spared and predominantly neovascularizations to be occluded: (a) Due to the disturbance of the blood-retina barrier, free dye molecules accumulate within the vascular wall. Using a dye with prolonged retention, such as phthalocyanine (CASPc), it is possible to thrombose neovascularizations 24 h post injection while leaving the physiological vasculature of the anterior segment of the rabbit eye unaffected. (b) Proliferating endothelial cells express high numbers of low-density lipoprotein (LDL) receptors. Chlorin e6 (Ce6), a potent photosensitizer, is covalently bound to LDL. Intravascularly, ce6-LDL complexes selectively label neovascular walls. Since ce6-LDL is incorporated intracellular into enzymatically active lysosomes, photothrombosis is effectively achieved at low drug and light doses in vivo. In addition, the induced damage is spatially confined to the inner vascular lining. We conclude that carrier-mediated PDT may offer a new and sensitive approach for selective treatment of intraocular neovascularizations.

Animals↗
PubMed1992

Towards continuous glucose monitoring: in vivo evaluation of a miniaturized glucose sensor implanted for several days in rat subcutaneous tissue.

A miniaturized amperometric, enzymatic, glucose sensor (outer diameter 0.45 mm) was evaluated after implantation in the subcutaneous tissue of normal rats. A simple experimental procedure was designed for the long-term assessment of the sensor's function which was performed by recording the current during an intraperitoneal glucose load. The sensor was calibrated by accounting for the increase in the current during the concomitant increase in plasma glucose concentration, determined in blood sampled at the tail vein. This made it possible to estimate the glucose concentration in subcutaneous tissue. During the glucose load, the change in subcutaneous glucose concentration followed that in blood with a lag time consistently shorter than 5 min. The estimations of subcutaneous glucose concentration during these tests were compared to the concomitant plasma glucose concentrations by using a grid analysis. Three days after implantation (n = 6 experiments), 79 estimations were considered accurate, except for five which were in the acceptable zone. Ten days after implantation (n = 5 experiments), 101 estimations were accurate, except for one value, which was still acceptable. The sensitivity was around 0.5 nA.mmol-1.l-1 on day 3 and day 10. A longitudinal study on seven sensors tested on different days demonstrated a relative stability of the sensor's sensitivity. Finally, histological examination of the zone around the implantation site revealed a fibrotic reaction containing neocapillaries, which could explain the fast response of the sensor to glucose observed in vivo, even on day 10. We conclude that this miniaturized glucose sensor, whose size makes it easily implanted, works for at least ten days after implantation into rat subcutaneous tissue.

Animals↗
PubMed1988

Site-directed neovessel formation in vivo.

Angiogenesis is an important component of organogenesis and wound repair and occurs during the pathology of oncogenesis, atherogenesis, and other disease processes. Thus, it is important to understand the physiological mechanisms that control neovascularization, especially with methods that permit the molecular dissection of the phenomenon in vivo. Heparin-binding growth factor-1 was shown to bind to collagen type I and type IV. When complexed with gelatin, heparin-binding growth factor-1 can induce neovascularization at polypeptide concentrations that are consistent with the biological activity of the mitogen in vitro. The adsorption strategy induces rapid blood vessel formation at and between organ- and tissue-specific sites and permits recovery of the site-specific implant for examination and manipulation by molecular methods.

Animals↗
PubMed1991

[Regeneration of the sciatic nerve in the rat modified by neurotrophic factors].

In the present study an experimental rat model is presented enabling analysis of nerve regeneration in vivo through preformed tissue holes. The tissue space allows to bridge a gap about 10 mm. The neovascularization could follow the physiological course using the way through the epi- and perineurium in the chamber. The regeneration rate was investigated with and without application of a mixture of gangliosides showing a significant difference between both groups. Gangliosides stimulated the axonal outgrowth and the restoration of well-vascularized nerve fascicles. Further investigations should examine the effects of different neurotrophic substances in the tube.

Animals↗
PubMed1990

Pseudopodia of capillary endothelium in ocular tissues.

The frequencies of pseudopodia projecting from capillaries of various parts of the eye were observed in 16 human eyes with a transmission electron microscope. The pseudopodia were found mainly projecting from the choriocapillaris and rarely seen in the retina, iris or ciliary body. The frequencies of pseudopodia from the choriocapillaris were not correlated with the localization in the fundus (macular area or peripheral fundus), age, sex, time elapsed between death or enucleation and fixation. The significance of pseudopodia from the choriocapillaris is unknown. However, there is the possibility that pseudopodia are related to choroidal neovascularization or have other physiological functions.

Adult↗
PubMed1992

Interleukin-8. A corneal factor that induces neovascularization.

A rabbit corneal pocket model was used to demonstrate that physiologic concentrations of human recombinant (r) IL-8 may induce corneal neovascularization. Computer-assisted analysis of sequential fluorescein angiograms showed that rIL-8 doses ranging from 2 to 40 ng/cornea (P = 0.01), but not high dose rIL-8 (400 ng/cornea), results in neovascularization within 14 days. Repeat fluorescein angiograms 6 weeks after placing angiogenic doses of rIL-8 demonstrated significant regression (P = 0.01) of the vascularity present at 2 weeks, suggesting that IL-8 angiogenesis undergoes dynamic modulation similar to that normally seen in wound healing. To our knowledge, this is the first study showing an angiogenic role for IL-8, a finding that emphasizes the interplay between inflammation and wound healing. Our results imply that corneal-derived IL-8 may be important in corneal neovascularization, in particular, and that IL-8 may modulate wound healing in general. Finally, these results raise the possibility that corneal-derived cytokines, such as IL-8, may obfuscate the effects of agents tested in experimental corneal pocket models.

Angiography↗
PubMed1990

A tumor suppressor-dependent inhibitor of angiogenesis is immunologically and functionally indistinguishable from a fragment of thrombospondin.

A secreted inhibitor of angiogenesis that is controlled by a tumor suppressor gene in hamster cells has been found to be similar to a fragment of the platelet and matrix protein thrombospondin. The two proteins were biochemically similar and immunologically crossreactive and could substitute for one another in two functional assays. Human thrombospondin inhibited neovascularization in vivo and endothelial cell migration in vitro, as does the hamster protein, gp140. gp140 sensitized smooth muscle cells to stimulation by epidermal growth factor, as does human thrombospondin. The thrombospondin gene has been localized on human chromosome 15. These results demonstrate a function for the ubiquitous adhesive glycoprotein thrombospondin that is likely to be important in the normal physiological down-regulation of neovascularization. In addition, they raise the possibility that thrombospondin may be one of a number of target molecules through which a tumor suppressor gene could act to restrain tumor growth.

Amino Acid Sequence↗
PubMed1990

[Characteristics of nutrition and certain mechanisms of antitumor resistance].

Nutrition (general caloricity, protein and fat content), immune system indices, hormonal status, neovascularization or proliferative processes are discussed in the review from the standpoint of their influence on mechanisms of the antitumour resistance. It is confirmed that such peculiarities of nutrition as moderate reduction of general caloricity and decrease of fat content can be considered as means increasing the antitumour resistance.

Dietary Fats↗
PubMed1987

Angiogenic factors.

Within the past 2 years, several angiogenic factors have been fully purified, their amino acid sequences determined, and their genes cloned. These polypeptides include acidic and basic fibroblast growth factor, angiogenin, and transforming growth factors alpha and beta. Other less well characterized angiogenesis factors have also been isolated, some of which are lipids. This article traces the discovery of the angiogenic factors and describes their possible significance in understanding growth regulation of the vascular system. When evaluated according to their putative targets, they appear to fall into two groups: those that act directly on vascular endothelial cells to stimulate locomotion or mitosis, and those that act indirectly by mobilizing host cells (for example, macrophages) to release endothelial growth factors. In addition to their presence in tumors undergoing neovascularization, the same angiogenic peptides are found in many normal tissues where neovascularization is not occurring. This suggests that physiological expression of angiogenic factors is tightly regulated. In addition to the persistent angiogenesis induced by tumors, it now appears that a variety of nonneoplastic diseases, previously thought to be unrelated, can be considered as "angiogenic diseases" because they are dominated by the pathologic growth of capillary blood vessels.

Angiogenesis Inducing Agents↗
PubMed1978

Development and ultrastructure of peripheral subretinal neovascularizations.

Anterior to the equator an additional vascular layer can regularly be found between peripheral retina and choroid. The vessels are located within Bruch's membrane, subjacent to the retinal pigment epithelium. Apparently, this layer is not present at birth and develops at a relatively young age. With the electron microscope all steps of vasculogenesis could be followed. The presence of such vessels also in the eye of a 29-year-old individual suggests that they represent a physiologic condition rather than an ageing change. In contrast to the subretinal neovascular membranes of the posterior fundus, these peripheral neovascularizations show no relation to any known fundus disease.

Adult↗