The effect of erythropoietin on the severity of retinopathy of prematurity

Early Postnatal Administration of Erythropoietin and Its Association with Neurodevelopmental Outcomes and Incidence of Intraventricular Hemorrhage and Hypoxic-Ischemic Encephalopathy: A Four-Week Observational Study

This study aimed to investigate the impact of early erythropoietin (EPO) administration on the neurodevelopment of newborns, specifically focusing on its effects on hypoxic-ischemic encephalopathy (HIE) and intraventricular hemorrhage (IVH). The primary objective was to determine whether early EPO administration could impact the short-term neurodevelopmental outcomes and provide safety in neonates at risk for neurodevelopmental disorders. Conducted at the "Louis Turcanu" Children's Emergency Clinical Hospital in Timisoara, Romania, this observational study included 121 neonates receiving EPO and 130 No EPO controls. EPO was administered within the first 48 h of life, with doses of 1000 U/kg that escalated to 2000 U/kg if necessary. Besides observing the occurrence of IVH and HIE, this study measured clinical and biochemical markers, including LDH, blood glucose, urea, creatinine, CPK, CRP, PCT, and erythropoietin levels alongside hematology and coagulation profiles. There were no significant differences in baseline characteristics between the groups. The EPO group showed significant reductions in LDH levels from days 1-3 to 7-10 (695.0 U/L to 442.0 U/L) and the APTT value (54.0 s) compared with the No EPO group (38.0 s). Notably, early EPO administration was associated with a significant decrease in HIE severity (beta coefficient: -0.38, p = 0.001). Additionally, lower gestational ages and hemoglobin levels correlated with increased severity of HIE. By week four, there was a significant reduction in moderate and severe HIE cases in the EPO group compared with controls (p = 0.001). Early administration of EPO in neonates significantly reduced the severity of IVH and HIE, suggesting its potential as a neuroprotective agent in neonatal care.

Effect of Probenecid on Endothelial Cell Growth Rate and Retinal Angiogenesis in an Oxygen-Induced Retinopathy Model

Objectives: Probenecid is an anion transport inhibitor, which, according to the connectivity map (CMap; a biological application database), interferes with hypoxia-induced gene expression changes in retinal vascular endothelial cells (ECs). Here, we investigated the influence of probenecid on retinal EC cytotoxicity and retinal neovascularization in a murine oxygen-induced retinopathy (OIR) model.

Methods: The retinal EC growth rate in the presence of hypoxia-mimicking concentrations of cobalt chloride (CoCl₂) was determined using the thiazolyl blue tetrazolium bromide (MTT) assay and proliferating cell nuclear antigen (PCNA) expression. In OIR rats, probenecid was administered by intraperitoneal injection (i.p.) from postnatal day (P) 1 to P7. The concentrations of vitreous humor vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF)-1α, and placental growth factor (PlGF) were determined by using the ELISA kit at P21. The amount of newly formed vascular lumen was evaluated by histopathological examination. Retinopathy and neovascularization were assessed by scoring isolectin B4 fluorescein–stained retinal flat mounts. Western blots for liver tissue HIF-1α and hepcidin (HAMP) were performed.

Results:In vitro, probenecid led to the recession of the hypoxia-induced EC growth rate. In vivo, compared to the OIR retina, the upregulation of VEGF, HIF-1α, and PlGF in phase II retinopathy of prematurity (ROP) was inhibited by probenecid administration. Moreover, probenecid ameliorated neovascularization and resulted in significantly reduced relative leakage fluorescence signal intensity in fluorescein-stained retinal flat mounts (p < 0.05). Probenecid alleviated the liver overactivation of HAMP and downregulation of HIF-1α in OIR rats.

Conclusions: This is the first demonstration that implies that probenecid might be a protective compound against retinal angiogenesis in OIR. These changes are accompanied with decreased hyperoxia-mediated hepcidin overproduction. Although the relevance of the results to ROP needs further research, these findings may help establish potential pharmacological targets based on the CMap database.

Use of erythropoietin in ophthalmology: a review

Erythropoietin (EPO) is a glycoprotein hormone that regulates hematopoiesis in the human body. The presence of EPO and its receptors in different tissues indicates that this hormone has extramedullary effects in other tissues, including the eye. We focus on the biological roles of this hormone in the development and normal physiologic functions of the eye. Furthermore, we explore the role of EPO in the management of different ocular diseases - including diabetic retinopathy, retinopathy of prematurity, inherited retinal degeneration, branch and central retinal vein occlusion, retinal detachment, traumatic optic neuropathy, optic neuritis, methanol optic neuropathy, nonarteritic anterior ischemic optic neuropathy, glaucoma, and scleral necrosis.

A safety review of drugs used for the treatment of retinopathy of prematurity

INTRODUCTION

Retinopathy of Prematurity (ROP) is a sight-threatening disease representing one of the main disabling diseases affecting premature newborns. Presently, ROP is treated by surgical interventions and drug therapies are limited to the off-label use of a little amount of molecules approved for other pathologies.

AREAS COVERED

Many drugs that may potentially be used in treating ROP are recently proposed, in many cases after the demonstration of their effectiveness in preclinical studies. In this review, the authors discuss safety and effectiveness of the main proposed approaches in the pharmacologic treatment of the disease, including approaches based on oxygen therapy and nutritional interventions.

EXPERT OPINION

Surgical approaches to ROP are not without side effects. However, most of the proposed pharmacologic interventions can also raise specific concerns. In particular, these approaches follow a curative paradigm and are proposed in patients once the disease has progressed, with an effectiveness that is often smaller than expected. A goal in the treatment of ROP would be moving the paradigm toward a preventive approach that could be potentially effective in treating extremely low birth weight preterm infants before ROP becomes manifest.

Retinopathy of prematurity: a review of risk factors and their clinical significance

Retinopathy of prematurity (ROP) is a retinal vasoproliferative disease that affects premature infants. Despite improvements in neonatal care and management guidelines, ROP remains a leading cause of childhood blindness worldwide. Current screening guidelines are primarily based on two risk factors: birth weight and gestational age; however, many investigators have suggested other risk factors, including maternal factors, prenatal and perinatal factors, demographics, medical interventions, comorbidities of prematurity, nutrition, and genetic factors. We review the existing literature addressing various possible ROP risk factors. Although there have been contradictory reports, and the risk may vary between different populations, understanding ROP risk factors is essential to develop predictive models, to gain insights into pathophysiology of retinal vascular diseases and diseases of prematurity, and to determine future directions in management of and research in ROP.

Early Erythropoietin Administration does not Increase the Risk of Retinopathy in Preterm Infants

BACKGROUND

Erythropoietin (EPO) administration prevents anemia of prematurity and may be associated with a significant increase in the risk of retinopathy of prematurity (ROP) in preterm infants. Nonetheless, early EPO treatment may prevent damage following retinal neovascularization. The aim of this meta-analysis was to elucidate whether EPO administration increases the risk of ROP.

METHODS

We searched MEDLINE, PubMed, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and the Cochrane Central Register of Controlled Trials with no language restrictions. Randomized controlled trials that reported the association between EPO treatment in preterm infants and ROP were eligible. All of the included studies were stratified into two groups according to the age of initiation of EPO treatment: before 8 days of age (early EPO), and 8-28 days of age (late EPO).

RESULTS

Thirteen studies were identified that included a total of 1999 preterm infants. EPO administration did not increase the risk of ROP of any stage or Stage ≥3 (any relative risk: 0.99, 95% confidence interval: 0.84-1.16, p = 0.89; Stage ≥3 relative risk: 1.34, 95% confidence interval: 0.90-1.99, p = 0.15). This trend remained unchanged in both the early and late EPO groups. There did not seem to be any evidence of publication bias for outcomes as the funnel plots were symmetrical.

CONCLUSION

EPO administration did not significantly increase the risk of ROP of any stage reported or Stage ≥3. Further clinical trials investigating the impact of EPO on ROP in premature infants should include all confounding factors to clarify this important issue.

Expanded criteria for retinopathy of prematurity screening in moderately preterm infants: Single-center pilot study

BACKGROUND

While developed countries seek to lower the gestational age and birthweight parameters in retinopathy of prematurity (ROP) screening, older, larger infants still develop ROP in other parts of the world. The aim of this study was therefore to define criteria to identify potential ROP developers who are outliers of the common screening range.

METHODS

A retrospective medical record review was performed in 147 inborn moderately preterm infants admitted to the neonatal intensive care unit during the study period. Univariate and logistic regression analysis was carried out.

RESULTS

Forty-two infants developed ROP. Gestational age (31.4 ± 1.1 vs 32.4 ± 1.0 weeks, P = 0.000) and birthweight (1607.7 ± 339.4 vs 1846.4 ± 317.2 g, P = 0.000) were lower in those who developed ROP. Respiratory distress syndrome (P = 0.026) and documented sepsis (P = 0.003) were significant comorbidities on univariate analysis. Inotrope need >72 h starting in the first week of life (P = 0.004; OR, 5.181) and more than three transfusions of packed red blood cells (P = 0.028; OR, 3.891) were also significant, both on univariate and multivariate analysis.

CONCLUSIONS

In moderately preterm infants, status should be evaluated in order to effectively select candidates for ROP screening without missing potential ROP developers.

Recombinant human erythropoietin improves neurological outcomes in very preterm infants

OBJECTIVE

To evaluate the efficacy and safety of repeated low-dose human recombinant erythropoietin (rhEPO) in the improvement of neurological outcomes in very preterm infants.

METHODS

A total of 800 infants of ≤32-week gestational age who had been in an intensive care unit within 72 hours after birth were included in the trial between January 2009 and June 2013. Preterm infants were randomly assigned to receive rhEPO (500IU/kg; n = 366) or placebo (n = 377) intravenously within 72 hours after birth and then once every other day for 2 weeks. The primary outcome was death or moderate to severe neurological disability assessed at 18 months of corrected age.

RESULTS

Death and moderate/severe neurological disability occurred in 91 of 338 very preterm infants (26.9%) in the placebo group and in 43 of 330 very preterm infants (13.0%) in the rhEPO treatment group (relative risk [RR] = 0.40, 95% confidence interval [CI] = 0.27-0.59, p < 0.001) at 18 months of corrected age. The rate of moderate/severe neurological disability in the rhEPO group (22 of 309, 7.1%) was significantly lower compared to the placebo group (57 of 304, 18.8%; RR = 0.32, 95% CI = 0.19-0.55, p < 0.001), and no excess adverse events were observed.

INTERPRETATION

Repeated low-dose rhEPO treatment reduced the risk of long-term neurological disability in very preterm infants with no obvious adverse effects. Ann Neurol 2016;80:24-34.

Pharmacologic interventions for the prevention and treatment of retinopathy of prematurity

Retinopathy of prematurity (ROP), a significant morbidity in prematurely born infants, is the most common cause of visual impairment and blindness in children and persists till adulthood. Strict control of oxygen therapy and prevention of intermittent hypoxia are the keys in the prevention of ROP, but pharmacologic interventions have decreased risk of ROP. Various drug classes such as methylxanthines (caffeine), VEGF inhibitors, antioxidants, and others have decreased ROP occurrence. The timing of pharmacologic intervention remains unsettled, but early prevention rather than controlling disease progression may be preferred. These drugs act through different mechanisms, and synergistic approaches should be considered to maximize efficacy and safety.

Erythropoietin in ophthalmology: A literature review

PURPOSE

To review the current literature on ocular application of erythropoietin (EPO).

METHODS

A comprehensive search was performed on Pubmed and Scopus databases. All selected articles were reviewed thoroughly by the authors to review current applications of the EPO in ocular diseases.

RESULTS

Various aspects of administration of EPO for different ischemic, traumatic, vascular, and degenerative disorders have been explained. The articles are generally preclinical with few small studies reporting clinical outcomes.

CONCLUSION

EPO has been used for the treatment of different ophthalmic conditions with promising results. Further studies are needed to elaborate the role of EPO in management of ocular diseases.

Retinopathy of Prematurity: Therapeutic Strategies Based on Pathophysiology

Retinopathy of prematurity (ROP) continues to be a major preventable cause of blindness and visual handicaps globally. With improved perinatal care, improved survival of moderately preterm infants, and limited resources for oxygen delivery and monitoring, more mature preterm infants are developing severe ROP in developing countries. The pathophysiology of ROP is characterized by two phases. Phase I ROP is due to vaso-obliteration beginning immediately after birth secondary to a marked decrease in vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1). Phase II begins around 33 weeks' postmenstrual age (PMA). During this phase, VEGF levels increase, especially if there is retinal hypoxia with increasing retinal metabolism and demand for oxygen leading to abnormal vasoproliferation. Since the original description of ROP in 1942 by Terry et al. [Am J Ophthalmol 1942;25:203-204], four epidemics of ROP have been observed. Prevention or early treatment of ROP involves careful titration of oxygen saturation by pulse oximeter (SpO2). Optimal SpO2 target remains elusive. Most of the large trials have focused on either a low SpO2 (85-89%) or a high SpO2 (91-95%) from the first day of birth to 36 weeks' PMA. Although the incidence of severe ROP and bronchopulmonary dysplasia decreased significantly, predischarge mortality was higher in these studies. Use of graded SpO2 during the 2 different phases of ROP (early, low SpO2 during phase I vs. late, high SpO2 during phase II) may be the best approach to prevent this disabling condition. Further trials should focus on this strategy. Other biological agents that are currently being studied include IGF-1 with IGF-binding protein-3 (rhIGF-1 + rhIGFBP-3) and propranolol. For advanced stages of ROP, laser ablation of avascular retina, early treatment of ROP (ETROP) protocol, intravitreal injection of anti-VEGF antibodies (e.g. bevacizumab) and vitrectomy are used to protect central vision and prevent retinal detachment. Long-term complications such as refractory errors, recurrence of ROP and risk of retinal detachment require continued follow-up with an ophthalmologist through adolescence and beyond. Optimal nutrition including adequate intake of omega-3 polyunsaturated fatty acids and decreasing infection/inflammation to promote normal vascularization are important strategies. Screening guidelines for ROP based on local incidence of ROP in different regions of the world are very important. Oxygen therapy is clearly a modifiable risk factor to decrease ROP that needs further study. Understanding the two phases of ROP will help to identify appropriate therapeutic strategies and improve visual outcomes in many preterm infants globally.

Safety and angiogenic effects of systemic gene delivery of a modified erythropoietin

Erythropoietin (EPO) is critical for red blood cell production and is also an effective neuroprotective agent. However, it may contribute to pathological angiogenesis. Here we investigate the angiogenic potential of EPO and a mutant form with attenuated erythropoietic activity, EPO-R76E, on primary human retinal microvascular endothelial cells (HRMECs) and in the adult retina. Assays of death, proliferation and tube formation were performed on HRMECs exposed to EPO, EPO-R76E or media alone. Postnatal day-9 wild-type mice were injected intramuscularly with adeno-associated virus vectors expressing either enhanced green fluorescent protein or EpoR76E. At 3 months, levels of EPO-R76E in the eye were quantified, and the health of the retinal vasculature was assessed by fluorescein angiography and isolectin immunolabeling. Immunohistochemistry, histology and electroretinogram (ERG) assessments were performed as measures of retinal health. Neither EPO nor EPO-R76E induced proliferation or tube formation in HRMECs under the conditions used. EPO-R76E decreased HRMEC death in a dose-dependent manner. Long-term systemic gene delivery of EPO-R76E was safe in terms of retinal vasculature, histology and the ERG in vivo. Our results show that EPO-R76E can block HRMEC death, consistent with its role in erythropoiesis and neuroprotection. In addition, long-term gene delivery of EPO-R76E is safe in the adult retina.

Use of erythropoietin is associated with threshold retinopathy of prematurity (ROP) in preterm ELBW neonates: a retrospective, cohort study from two large tertiary NICUs in Italy

BACKGROUND

Retinopathy of prematurity (ROP) is a multifactorial disease with evidence of many associated risk factors. Erythropoietin has been reported to be associated with this disorder in a murine model, as well as in humans in some single-center reports. We reviewed the data from two large tertiary NICUs in Italy to test the hypothesis that the use of erythropoietin may be associated with the development of the most severe stages of ROP in extremely low birth weight (ELBW) neonates.

DESIGN/METHODS

Retrospective study by review of patient charts and eye examination index cards on infants with birth weight <1000g admitted to two large tertiary NICUs in Northern Italy (Sant'Anna Hospital NICU in Torino, and Ca' Foncello Hospital Neonatology in Treviso) in the years 2005 to 2007. Standard protocol of administration of EPO in the two NICUs consisted of 250 UI/kg three times a week for 6-week courses (4-week in 1001-1500g infants). Univariate analysis was performed to assess whether the use of EPO was associated with severe (threshold) ROP. A control, multivariate statistical analysis was performed by entering into a logistic regression model a number of neonatal and perinatal variables that - in univariate analysis - had been associated with threshold ROP.

RESULTS

During the study period, 211 ELBW infants were born at the two facilities and survived till discharge. Complete data were obtained for 197 of them. Threshold retinopathy of prematurity occurred in 26.9% (29 of 108) of ELBW infants who received erythropoietin therapy, as compared with 13.5% (12 of 89) of those who did not receive erythropoietin (OR 2.35; 95% CI 1.121-4.949; p=0.02 in univariate analysis, and p=0.04 at multivariate logistic regression after controlling for the following variables: birth weight, gestational age, days on supplemental oxygen, systemic fungal infection, vaginal delivery). Use of erythropoietin was not significantly associated with other major sequelae of prematurity (intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis). © 2014 Elsevier Ireland Ltd. All rights reserved.

CONCLUSIONS

Use of erythropoietin is an additional, independent predictor of threshold ROP in ELBW neonates. Larger prospective, population-based studies should further clarify the extent of this association.