scholarly journals Posterior Segment Approach for Subretinal Transplantation or Injection in the Canine Model

2001 ◽  
Vol 10 (3) ◽  
pp. 317-327 ◽  
Author(s):  
Maria E. Verdugo ◽  
Julie Alling ◽  
Eliot S. Lazar ◽  
Manuel Del Cerro ◽  
Jharna Ray ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Canine Model ◽  
Posterior Segment ◽  
Fundus Photography ◽  
Subretinal Space ◽  
Rpe Cells ◽  
Injection Volume ◽  
Clinical Complications ◽  
Optimal Injection ◽  
Transplantation Technique

A posterior segment approach for cell transplantation or injection into the subretinal space of the dog has been developed. Controlled penetration to the subretinal space was achieved using a 29-gauge injection cannula, either blunted or with a 30° sharpened bevel, and partially ensheathed with moveable plastic tubing. Depending on the injection volume used, the retina detached, and the fluid was reabsorbed within 1 – 3 weeks, although for smaller volumes the retina reattached within a matter of days. The optimal injection volume used was between 100 and 150 μl, or two injections of 55 μl each. By ophthalmoscopy following the surgery, it was possible to serially monitor the injection site and retinal bleb through fundus photography. Light microscopy demonstrates the distribution of stable, viable RPE cells in the subretinal space up to 6 months. The transplantation technique developed for the dog is atraumatic and free from any major surgical or clinical complications. It can be readily used to deliver cells or fluids to localized regions of the subretinal space.

Degradation of extracellular ATP by the retinal pigment epithelium

2005 ◽  
Vol 289 (3) ◽  
pp. C617-C624 ◽  
Author(s):  
David Reigada ◽  
Wennan Lu ◽  
Xiulan Zhang ◽  
Constantin Friedman ◽  
Klara Pendrak ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Adenosine Diphosphate ◽  
Cell Types ◽  
P2y Receptors ◽  
Extracellular Atp ◽  
Pcr Analysis ◽  
Subretinal Space ◽  
Rpe Cells ◽  
Mrs 2179

Stimulation of ATP or adenosine receptors causes important physiological changes in retinal pigment epithelial (RPE) cells that may influence their relationship to the adjacent photoreceptors. While RPE cells have been shown to release ATP, the regulation of extracellular ATP levels and the production of dephosphorylated purines is not clear. This study examined the degradation of ATP by RPE cells and the physiological effects of the adenosine diphosphate (ADP) that result. ATP was readily broken down by both cultured human ARPE-19 cells and the apical membrane of fresh bovine RPE cells. The compounds ARL67156 and βγ-mATP inhibited this degradation in both cell types. RT-PCR analysis of ARPE-19 cells found mRNA message for multiple extracellular degradative enzymes; ectonucleotide pyrophosphatase/phosphodiesterase eNPP1, eNPP2, and eNPP3; the ectoATPase ectonucleoside triphosphate diphosphohydrolase NTPDase2, NTPDase3, and some message for NTPDase1. Considerable levels of ADP bathed RPE cells, consistent with a role for NTPDase2. ADP and ATP increased levels of intracellular Ca2+. Both responses were inhibited by thapsigargin and P2Y1 receptor inhibitor MRS 2179. Message for both P2Y1 and P2Y12 receptors was detected in ARPE-19 cells. These results suggest that extracellular degradation of ATP in subretinal space can result in the production of ADP. This ADP can stimulate P2Y receptors and augment Ca2+ signaling in the RPE.

Posterior Segment Findings in Patients on Extracorporeal Membrane Oxygenation

2020 ◽  
Vol 4 (6) ◽  
pp. 490-493
Author(s):  
Halward Martin John Blegen ◽  
Andrew Lemuel Plaster ◽  
Samuel David Hobbs ◽  
Donovan Stephen Reed ◽  
Joseph Anthony Santamaria ◽  
...  
Keyword(s):  
Extracorporeal Membrane Oxygenation ◽  
Demographic Data ◽  
Hemodynamic Instability ◽  
Retinal Hemorrhage ◽  
Posterior Segment ◽  
Fundus Photography ◽  
Initial Assessment ◽  
Membrane Oxygenation ◽  
Retinal Pathology ◽  
Intraocular Hemorrhage

Purpose: Extracorporeal membrane oxygenation (ECMO) is an established treatment modality for critically ill patients with cardiopulmonary failure, yet little is known of the ocular pathology in this population. The aim of this study is to characterize the posterior segment findings of ECMO patients. Methods: This study is a retrospective analysis of 20 ECMO patients evaluated by ophthalmology from September 2012 to May 2019 at a level 1 trauma center. Comprehensive examinations assessed for intraocular pathology. Demographic data, exam findings, and mortality were analyzed. Results: The sample size consisted of 20 patients; a majority were male (75%), and mean age was 37.4 years (interquartile range, 26.75-50 years). All patients received ECMO for care of acute respiratory distress syndrome (ARDS). Average duration of ECMO therapy was 9.6 ± 6.5 days. Eleven (55%) patients had acute retinal pathology, including Purtscher-like retinopathy (20%), intraocular hemorrhage (50%), and septic chorioretinitis (bacterial or fungal, 10%). Location of hemorrhage included the retina (40%), vitreous (30%), and optic disc (15%). Sixty percent (n = 12) of patients were unable to provide a subjective history on initial assessment. Ultimately, 5 out of 20 patients (25%) died of systemic illness during their hospital stay. Conclusion: This study demonstrates high rates of retinal pathology, most commonly vitreous and/or retinal hemorrhage alongside a Purtscher-like retinopathy. This is likely secondary to complications of anticoagulation, microthrombi, septicemia, and hemodynamic instability. We found a mortality rate slightly lower than that of prior ECMO studies. Prospective studies with pre-ECMO and post-ECMO fundus photography is warranted for better understanding of these medically complex patients.

Release of ATP from retinal pigment epithelial cells involves both CFTR and vesicular transport

2005 ◽  
Vol 288 (1) ◽  
pp. C132-C140 ◽  
Author(s):  
David Reigada ◽  
Claire H. Mitchell
Keyword(s):  
Epithelial Cells ◽  
Apical Membrane ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Vesicular Transport ◽  
Atp Release ◽  
Retinal Pigment Epithelial Cells ◽  
Subretinal Space ◽  
Transport Pathways ◽  
Rpe Cells

The retinal pigment epithelium (RPE) faces the photoreceptor outer segments and regulates the composition of the interstitial subretinal space. ATP enhances fluid movement from the subretinal space across the RPE. RPE cells can themselves release ATP, but the mechanisms and polarity of this release are unknown. The RPE expresses the cystic fibrosis transmembrane conductance regulator (CFTR), and CFTR is associated with ATP release in other epithelial cells. However, an increasing number of reports have suggested that the exocytotic pathway contributes to release. In the present study, we examined the involvement of CFTR and the vesicular pathway in ATP release from RPE cells. Release from cultured human ARPE-19 cells and across the apical membrane of fresh bovine RPE cells in an eyecup was studied. A cAMP cocktail to activate CFTR triggered ATP release from fresh and cultured RPE cells. Release from both RPE preparations was largely prevented by the broad-acting blocker glibenclamide and the specific thiazolidinone CFTR inhibitor CFTR-172. The block by CFTR-172 was enhanced by preincubation and prevented ATP release with 3.5 μM IC50. The rise in intracellular Ca2+ accompanying hypotonic challenge was prevented by CFTR-172. The vesicular transport inhibitor brefeldin A prevented ATP release after stimulation with both hypotonic and cAMP conditions, suggesting vesicular insertion was also involved. These results show an intimate involvement of CFTR in ATP release from RPE cells which can autostimulate receptors on the apical membrane to modify Ca2+ signaling. The requirement for both CFTR and vesicular transport pathways suggests vesicular insertion of CFTR may underlie the release of ATP.

Protection of Photoreceptor Cells from Phototoxicity by Transplanted Retinal Pigment Epithelial Cells Expressing Different Neurotrophic Factors

2005 ◽  
Vol 14 (10) ◽  
pp. 799-808 ◽  
Author(s):  
Toshiaki Abe ◽  
Yoko Saigo ◽  
Masayoshi Hojo ◽  
Tetsuya Kano ◽  
Ryosuke Wakusawa ◽  
...  
Keyword(s):  
Neurotrophic Factors ◽  
Retinal Pigment Epithelial ◽  
Outer Nuclear Layer ◽  
Retinal Pigment ◽  
Green Fluorescence Protein ◽  
Retinal Pigment Epithelial Cells ◽  
Subretinal Space ◽  
Egfp Gene ◽  
Rpe Cells ◽  
Pigment Epithelial

Transplantation of cells or tissues and the intravitreal injection of neurotrophic factors are two methods that have been used to treat retinal diseases. The purpose of this study was to examine the effects of combining both methods: the transplantation of retinal pigment epithelial (RPE) cells expressing different neurotrophic factors. The neutrophic factors were Axokine, brain derived-neurotrophic factor (BDNF), and basic fibroblast growth factor (bFGF). The enhanced green fluorescence protein (eGFP) gene was used as a reporter gene. These genes were transduced into RPE cells by lipofection, selected by antibiotics, and transplanted into the subretinal space of 108 rats. The rats were examined at 1 week and 3 months after the transplantation to determine whether the transduced cells were present, were expressing the protein, and were able to protect photoreceptors against phototoxicity. The survival of the transplanted cells was monitored by the presence of eGFP. The degree of protection was determined by the thickness of the outer nuclear layer. Our results showed that the degree of photoreceptor protection was different for the different types of neurotrophic factors at 1 week. After 3 months, the number of surviving transplanted cell was markedly reduced, and protection was observed only with the BDNF-transduced RPE cells. A significant degree of rescue was also observed by BDNF-transduced RPE cells in the nontransplanted area of the retina at both the early and late times. Lymphocytic infiltration was not detected in the vitreous, retina, and choroid at any time. We conclude that the transplantation of BDNF-transduced RPE cells can reduce the photoreceptor damage induced by phototoxicity in the transplanted area and weakly in the nontransplanted area.

Optimal injection volume of epinephrine for endoscopic prevention of recurrent peptic ulcer bleeding

2004 ◽  
Vol 60 (6) ◽  
pp. 875-880 ◽  
Author(s):  
Chang-Hwan Park ◽  
Soo-Jung Lee ◽  
Jeong-Ho Park ◽  
Jae-Hong Park ◽  
Wan-Sik Lee ◽  
...  
Keyword(s):  
Peptic Ulcer ◽  
Ulcer Bleeding ◽  
Peptic Ulcer Bleeding ◽  
Injection Volume ◽  
Optimal Injection

scholarly journals Effects of hypoxia on potassium homeostasis and pigment epithelial cells in the cat retina.

1984 ◽  
Vol 84 (6) ◽  
pp. 945-970 ◽  
Author(s):  
R A Linsenmeier ◽  
R H Steinberg
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Basal Membrane ◽  
Complete Recovery ◽  
Membrane Resistance ◽  
Arterial Oxygen ◽  
Subretinal Space ◽  
Rpe Cells ◽  
Cat Retina ◽  
High K

Intracellular recordings show that light-evoked hyperpolarizations of the apical and basal membranes of the cat retinal pigment epithelium (RPE) are altered by mild hypoxia. RPE cells, like glia, have a high K+ conductance, and measurements with K+-sensitive microelectrodes show that the hypoxic changes in the RPE cell are largely the result of changes in extracellular [K+] in the subretinal space [( K+]o) rather than direct effects on RPE cells. During hypoxia, light-evoked [K+]o responses and membrane responses have longer times to peak, slower and less complete recovery during illumination, and larger amplitudes. In addition to the effects on light-evoked responses, hypoxia causes a depolarization of first the apical and then the basal membranes of RPE cells under dark-adapted conditions. The basal depolarization is accompanied by a decrease in basal membrane resistance. These depolarizations appear to be caused by a rapid increase in [K+]o at the onset of hypoxia, which is maximal in dark adaptation, and smaller if the retina is subjected to maintained illumination. All of the effects are graded with the severity of hypoxia and can be observed at arterial oxygen tensions as high as 65 mmHg, although the threshold may be even higher. We argue that the origin of hypoxic [K+]o changes is probably an inhibition of the photoreceptors' Na+/K+ pump. This work then suggests that photoreceptors are more sensitive to hypoxia than previously believed, and that the high oxygen tension normally provided by the choroidal circulation is necessary for normal photoreceptor function.

The Utility of Routine Fundus Photography Screening for Posterior Segment Disease

Ophthalmology ◽  
2020 ◽  
Author(s):  
Nakul S. Shekhawat ◽  
Leslie M. Niziol ◽  
Sankalp S. Sharma ◽  
Sanil Joseph ◽  
Alan L. Robin ◽  
...  
Keyword(s):  
Posterior Segment ◽  
Fundus Photography

scholarly journals Key Role for CRB2 in the Maintenance of Apicobasal Polarity in Retinal Pigment Epithelial Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Antonio E. Paniagua ◽  
Alicia Segurado ◽  
Jorge F. Dolón ◽  
Julián Esteve-Rudd ◽  
Almudena Velasco ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Cell Junction ◽  
Subretinal Space ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Apicobasal Polarity

Apicobasal polarity is essential for epithelial cell function, yet the roles of different proteins in its completion is not fully understood. Here, we have studied the role of the polarity protein, CRB2, in human retinal pigment epithelial (RPE) cells during polarization in vitro, and in mature murine RPE cells in vivo. After establishing a simplified protocol for the culture of human fetal RPE cells, we studied the temporal sequence of the expression and localization of polarity and cell junction proteins during polarization in these epithelial cells. We found that CRB2 plays a key role in tight junction maintenance as well as in cell cycle arrest. In addition, our studies in vivo show that the knockdown of CRB2 in the RPE affects to the distribution of different apical polarity proteins and results in perturbed retinal homeostasis, manifested by the invasion of activated microglial cells into the subretinal space. Together our results demonstrate that CRB2 is a key protein for the development and maintenance of a polarized epithelium.

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