Emerging treatments for retinopathy of prematurity

Oxidative Stress Markers and the Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a leading cause of potentially preventable blindness in low birth weight preterm infants. Several perinatal and postnatal factors contribute to the incomplete maturation of retinal vascularization, leading to oxidative stress damage. Literature data suggest that the lack of equilibrium between pro-oxidants and anti-oxidants plays a key role. In the last decade, there has been an increasing interest in identifying the antecedents of ROP and the relevant pathogenic mechanisms involved. In this context, a panel of biomarkers was investigated in order to achieve early detection of oxidative stress occurrence and to prevent retinal damage. Several nutritional elements have been found to play a relevant role in ROP prevention. At this stage, no conclusive data have been shown to support the usefulness of one biomarker over another. Recently, the Food and Drugs Administration, the European Medicine Agency, and the National Institute of Health proposed a series of criteria in order to promote the inclusion of new biomarkers in perinatal clinical guidelines and daily practice. The aim of the present review is to offer an update on a panel of biomarkers, currently investigated as potential predictors of ROP, highlighting their strengths and weaknesses.

Anti-secretogranin III therapy of oxygen-induced retinopathy with optimal safety

Retinopathy of prematurity (ROP) with pathological retinal neovascularization is the most common cause of blindness in children. ROP is currently treated with laser therapy or cryotherapy, both of which may adversely affect the peripheral vision with limited efficacy. Owing to the susceptibility of the developing retina and vasculatures to pharmacological intervention, there is currently no approved drug therapy for ROP in preterm infants. Secretogranin III (Scg3) was recently discovered as a highly disease-restricted angiogenic factor, and a Scg3-neutralizing monoclonal antibody (mAb) was reported with high efficacy to alleviate oxygen-induced retinopathy (OIR) in mice, a surrogate model of ROP. Herein we independently investigated the efficacy of anti-Scg3 mAb in OIR mice and characterized its safety in neonatal mice. We developed a new Scg3-neutralizing mAb recognizing a distinct epitope and independently established the therapeutic activity of anti-Scg3 therapy to alleviate OIR-induced pathological retinal neovascularization in mice. Importantly, anti-Scg3 mAb showed no detectable adverse effects on electroretinography and developing retinal vasculature. Furthermore, systemic anti-Scg3 mAb induced no renal tubular injury or abnormality in kidney vessel development and body weight gain of neonatal mice. In contrast, anti-vascular endothelial growth factor drug aflibercept showed significant side effects in neonatal mice. These results suggest that anti-Scg3 mAb may have the safety and efficacy profiles required for ROP therapy.

Anti-vascular endothelial growth factor (VEGF) drugs for treatment of retinopathy of prematurity

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a key role in angiogenesis in foetal life. Researchers have recently attempted to use anti-VEGF agents for the treatment of retinopathy of prematurity (ROP), a vasoproliferative disorder. The safety and efficacy of these agents in preterm infants with ROP is currently uncertain.

OBJECTIVES

To evaluate the efficacy and safety of anti-VEGF drugs when used either as monotherapy, that is without concomitant cryotherapy or laser therapy, or in combination with planned cryo/laser therapy in preterm infants with type 1 ROP (defined as zone I any stage with plus disease, zone I stage 3 with or without plus disease, or zone II stage 2 or 3 with plus disease).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 11), MEDLINE (1966 to 11 December 2016), Embase (1980 to 11 December 2016), CINAHL (1982 to 11 December 2016), and conference proceedings.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that evaluated the efficacy or safety of administration, or both, of anti-VEGF agents compared with conventional therapy in preterm infants with ROP.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane and Cochrane Neonatal methods for data collection and analysis. We used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

Six trials involving a total of 383 infants fulfilled the inclusion criteria. Five trials compared intravitreal bevacizumab (n = 4) or ranibizumab (n = 1) with conventional laser therapy (monotherapy), while the sixth study compared intravitreal pegaptanib plus conventional laser therapy with laser/cryotherapy (combination therapy).When used as monotherapy, bevacizumab/ranibizumab did not reduce the risk of complete or partial retinal detachment (3 studies; 272 infants; risk ratio (RR) 1.04, 95% confidence interval (CI) 0.21 to 5.13; risk difference (RD) 0.00, 95% CI -0.04 to 0.04; very low-quality evidence), mortality before discharge (2 studies; 229 infants; RR 1.50, 95% CI 0.26 to 8.75), corneal opacity requiring corneal transplant (1 study; 286 eyes; RR 0.34, 95% CI 0.01 to 8.26), or lens opacity requiring cataract removal (3 studies; 544 eyes; RR 0.15, 95% CI 0.01 to 2.79). The risk of recurrence of ROP requiring retreatment also did not differ between groups (2 studies; 193 infants; RR 0.88, 95% CI 0.47 to 1.63; RD -0.02, 95% CI -0.12 to 0.07; very low-quality evidence). Subgroup analysis showed a significant reduction in the risk of recurrence in infants with zone I ROP (RR 0.15, 95% CI 0.04 to 0.62), but an increased risk of recurrence in infants with zone II ROP (RR 2.53, 95% CI 1.01 to 6.32). Pooled analysis of studies that reported eye-level outcomes also revealed significant increase in the risk of recurrence of ROP in the eyes that received bevacizumab (RR 5.36, 95% CI 1.22 to 23.50; RD 0.10, 95% CI 0.03 to 0.17). Infants who received intravitreal bevacizumab had a significantly lower risk of refractive errors (very high myopia) at 30 months of age (1 study; 211 eyes; RR 0.06, 95% CI 0.02 to 0.20; RD -0.40, 95% CI -0.50 to -0.30; low-quality evidence).When used in combination with laser therapy, intravitreal pegaptanib was found to reduce the risk of retinal detachment when compared to laser/cryotherapy alone (152 eyes; RR 0.26, 95% CI 0.12 to 0.55; RD -0.29, 95% CI -0.42 to -0.16; low-quality evidence). The incidence of recurrence of ROP by 55 weeks' postmenstrual age was also lower in the pegaptanib + laser therapy group (76 infants; RR 0.29, 95% CI 0.12 to 0.7; RD -0.35, 95% CI -0.55 to -0.16; low-quality evidence). There was no difference in the risk of perioperative retinal haemorrhages between the two groups (152 eyes; RR 0.62, 95% CI 0.24 to 1.56; RD -0.05, 95% CI -0.16 to 0.05; very low-quality evidence). However, the risk of delayed systemic adverse effects with any of the three anti-VEGF drugs is not known.

AUTHORS' CONCLUSIONS

Implications for practice: Intravitreal bevacizumab/ranibizumab, when used as monotherapy, reduces the risk of refractive errors during childhood but does not reduce the risk of retinal detachment or recurrence of ROP in infants with type 1 ROP. While the intervention might reduce the risk of recurrence of ROP in infants with zone I ROP, it can potentially result in higher risk of recurrence requiring retreatment in those with zone II ROP. Intravitreal pegaptanib, when used in conjunction with laser therapy, reduces the risk of retinal detachment as well as the recurrence of ROP in infants with type 1 ROP. However, the quality of the evidence was very low to low for most outcomes due to risk of detection bias and other biases. The effects on other critical outcomes and, more importantly, the long-term systemic adverse effects of the drugs are not known. Insufficient data precludes strong conclusions favouring routine use of intravitreal anti-VEGF agents - either as monotherapy or in conjunction with laser therapy - in preterm infants with type 1 ROP.

IMPLICATIONS FOR RESEARCH

Further studies are needed to evaluate the effect of anti-VEGF agents on structural and functional outcomes in childhood and delayed systemic effects including adverse neurodevelopmental outcomes.

The omega-3 and retinopathy of prematurity relationship

The aim of this article is to examine the effect of omega-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFAs) intake on retinopathy of prematurity (ROP) by reviewing the experimental and clinical trials conducted on animal models and infants. LCPUFAs demonstrate cytoprotective and cytotherapeutic actions contributing to a number of anti-angiogenic and neuroprotective mechanisms within the retina. Their intake appears to have a beneficial effect on ischemia, oxidative stress, inflammation and cellular signaling mechanisms, influencing retinal cell gene expression and cellular differentiation. ω-3 LCPUFAs may modulate metabolic processes that activate molecules implicated in the pathogenesis of vasoproliferative and neurodegenerative retinal diseases such as ROP.

Screening and Treatment in Retinopathy of Prematurity

BACKGROUND

More than 11 000 children are examined for possible retinopathy of prematurity in Germany each year, and 2-5% of them are treated for it. Even though screening and treatment programs are in place, the affected children can still suffer visual impairment.

METHODS

In this article, we summarize the pathogenesis, screening, and treatment of retinopathy of prematurity on the basis of a selective review of pertinent literature, retrieved by a PubMed search. The article centers on publications from 2011 to 2015 on the new option of treatment with VEGF inhibitors and discusses it in comparison to laser therapy.

RESULTS

All premature neonates with a low gestational age at birth, low birth weight, or prolonged exposure to supplemental oxygen must undergo screening by an ophthalmologist. Laser therapy is effective for stages 1-3 and for aggressive posterior retinopathy of prematurity. Its disadvantages are the induction of scarring and the development of severe myopia in 17-40% of the children so treated. Anti-VEGF treatment (VEGF = vascular endothelial growth factor) does not induce any visible scarring and seems to cause less myopia, but long-term data on safety, dosing, and the choice of anti-VEGF drug are still lacking.

CONCLUSION

The available evidence for anti-VEGF treatment is on a much lower level than the evidence for laser therapy. Anti-VEGF may be a way to avoid the disadvantages of laser therapy (scarring and severe myopia). Unlike laser therapy, however, the intravitreal injection of VEGF inhibitors may suppress systemic VEGF levels and potentially harm the developing brain, lungs, or other organs. The currently open questions about anti-VEGF treatment concern its dosing, choice of drug, and long-term safety.

Efficacy of intravitreal bevacizumab for zone-II retinopathy of prematurity

PURPOSE

To assess the effect of intravitreal bevacizumab for Type 1 retinopathy of prematurity (ROP) in zone II ROP.

METHODS

We conducted a randomized clinical trial. Preterm infants with a gestational age less than 34 weeks or birthweight less than 2000 g were examined at 4 weeks chronological age or 31 weeks postmenstrual age (whichever was later). Preterm infants with Zone-II/Stage 2 or 3 and plus disease were included. Eligible infants were randomized to receive either conventional indirect laser therapy or intravitreal bevacizumab injections (0.625 mg/0.025 ml). The primary outcome was defined as treatment failure: ROP persistence or recurrence by 90 weeks postmenstrual age.

RESULTS

Our study population comprised 79 infants (158 eyes) with Zone-II ROP. Randomly, 43 infants (86 eyes) were assigned to receive intravitreal bevacizumab and 36 infants (72 eyes) to receive conventional indirect laser therapy. All the infants were followed up at least until 90 weeks postmenstrual age. Stage-3 ROP recurred in nine eyes (10.5%) in the bevacizumab group and one eye (1.4%) in the laser group (p value = 0.018). In recurrent cases after the second treatment, ROP in eight of the nine eyes (88.8%) in the bevacizumab group and the eye in the laser group regressed.

CONCLUSION

Recurrence of neovascularization with bevacizumab monotherapy seems to be higher than that with conventional laser therapy among infants with Type 1 ROP in zone II ROP but reinjection of bevacizumab causes regression in most recurrent cases.

Anti-vascular endothelial growth factor (VEGF) drugs for treatment of retinopathy of prematurity

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a key role in angiogenesis in fetal life. Recently, researchers have attempted to use anti-VEGF agents for the treatment of retinopathy of prematurity (ROP), a vasoproliferative disorder. There is currently uncertainty regarding the safety and efficacy of these agents in preterm infants with ROP.

OBJECTIVES

To evaluate the efficacy and safety of anti-VEGF drugs when used either as monotherapy, i.e. without concomitant cryotherapy or laser therapy or in combination with planned cryo/laser therapy in preterm infants with type 1 ROP (defined as zone I any stage with plus disease, zone I stage 3 with or without plus disease or zone II stage 2 or 3 with plus disease).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 1), MEDLINE (1966 to January 1, 2016), EMBASE (1980 to January 1, 2016), CINAHL (1982 to January 1, 2016), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that evaluated the efficacy and safety of administration, or both, of anti-VEGF agents compared with conventional therapy in premature infants with ROP.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane and Cochrane Neonatal methods for data collection and analysis.

MAIN RESULTS

Three trials, in which 239 infants participated, fulfilled the inclusion criteria. Two trials compared intravitreal bevacizumab with conventional laser therapy (monotherapy) while the third compared intravitreal pegaptanib plus laser treatment with laser and cryotherapy (combination therapy) in infants with type 1 ROP.Of the two studies that evaluated intravitreal bevacizumab, one randomized infants while the other randomized eyes of the infants to the intervention and control groups. The former did not report any difference in the incidence of complete or partial retinal detachment between the groups (143 infants; RR 1.04, 95% CI 0.21 to 5.13; RD 0.00, 95% CI -0.06 to 0.07; very low quality evidence) but reported a significant reduction in the risk of refractive errors - very high myopia - at 30 months of age (211 eyes; RR 0.06, 95% CI 0.02 to 0.20; RD -0.40, 95% CI -0.50 to -0.30; low quality evidence) and recurrence of ROP by 54 weeks' postmenstrual age (143 infants; RR 0.22, 95% CI 0.08 to 0.62; RD -0.20, 95% CI -0.31 to -0.09; moderate quality evidence) in the bevacizumab group. The study found no difference in the risk of mortality before discharge from the hospital (150 infants; RR 1.50; 95% CI 0.26 to 8.75; RD 0.01; 95% CI -0.04 to 0.07; low quality evidence), mortality at 30 months of age (150 infants; RR 0.86, 95% CI 0.30 to 2.45; RD -0.01; 95% CI -0.10 to 0.08; low quality evidence), corneal opacity requiring corneal transplant (286 eyes; RR 0.34, 95% CI 0.01 to 8.26; RD -0.01; 95% CI -0.03 to 0.02; very low quality evidence), or lens opacity requiring cataract removal (286 eyes; RR 0.15, 95% CI 0.01 to 2.79; RD -0.02; 95% CI -0.05 to 0.01; very low quality evidence). The second trial that randomized eyes of the infants did not find any difference in the risk of complete retinal detachment between the eyes randomized to bevacizumab and those that were randomized to laser therapy (13 eyes; RR 0.33, 95% CI 0.01 to 7.50; RD -0.08, 95% CI -0.27 to 0.11).When used in combination with laser therapy, intravitreal pegaptanib was found to reduce the risk of retinal detachment when compared to laser/cryotherapy alone (152 eyes; RR 0.26, 95% CI 0.12 to 0.55; RD -0.29, 95% CI -0.42 to -0.16; low quality evidence). The incidence of recurrence of ROP by 55 weeks' postmenstrual age was also lower in the pegaptanib + laser therapy group (76 infants; RR 0.29, 95% CI 0.12 to 0.7; RD -0.35, 95% CI -0.55 to -0.16; low quality evidence). There was no difference in the risk of perioperative retinal haemorrhages between the two groups (152 eyes; RR 0.62, 95% CI 0.24 to 1.56; RD -0.05, 95% CI -0.16 to 0.05; very low quality evidence). The risk of delayed systemic adverse effects with either of the drugs is, however, not known.

IMPLICATIONS FOR PRACTICE

Intravitreal bevacizumab reduces the risk of refractive errors during childhood when used as monotherapy while intravitreal pegaptanib reduces the risk of retinal detachment when used in conjunction with laser therapy in infants with type 1 ROP. Quality of evidence was, however, low for both the outcomes because of the risk of detection and other biases. Effect on other critical outcomes and, more importantly, the long-term systemic adverse effects of the drugs are not known. The insufficient data precludes strong conclusions favouring routine use of intravitreal anti-VEGF agents in preterm infants with type 1 ROP.

IMPLICATIONS FOR RESEARCH

Further studies are needed to evaluate the effect of anti-VEGF agents on structural and functional outcomes in childhood and delayed systemic adverse effects such as myocardial dysfunction and adverse neurodevelopmental outcomes.

Sildenafil attenuates vaso-obliteration and neovascularization in a mouse model of retinopathy of prematurity

PURPOSE

We sought to determine the effect of sildenafil on retinal vascular changes in a mouse model of oxygen-induced retinopathy (OIR).

METHODS

Vascular defects in OIR mice were quantified by measuring vaso-obliteration at postnatal days 12 and 17 (P12 and P17) and neovascularization at P17 to compare sildenafil-treated to dextrose-treated OIR mice. Retinal HIF1α protein expression was quantified by Western blotting and normalized to that of β-actin. Right ventricular hypertrophy was measured by Fulton's index as a surrogate for hyperoxia-induced pulmonary hypertension.

RESULTS

At P12, OIR mice treated with sildenafil demonstrated a 24% reduction in vaso-obliteration (P < 0.05), whereas at P17, treated animals showed a 50% reduction in neovascularization (P < 0.05) compared to dextrose-treated controls. Sildenafil-treated OIR mice had stabilization of retinal HIF1α at P12, immediately after hyperoxia. At P17, sildenafil-treated OIR mice had decreased HIF1α relative to untreated mice. OIR mice developed right ventricle hypertrophy that was significant compared to that in room air controls, which was abrogated by sildenafil.

CONCLUSIONS

Sildenafil treatment significantly decreased retinal vaso-obliteration and neovascularization in a mouse OIR model. These effects are likely due to sildenafil-induced HIF1α stabilization during hyperoxia exposure. Furthermore, we confirm disease overlap by showing that OIR mice also develop hyperoxia-induced right ventricular hypertrophy, which is prevented by sildenafil. This study is a first step toward delineating a potential therapeutic role for sildenafil in OIR and further suggests that there may be common pathophysiologic mechanisms underlying hyperoxia-induced retinal and pulmonary vascular disease.

Stratified control of IGF-I expression by hypoxia and stress hormones in osteoblasts

Bone cells respond to the integrated effects of local and systemic regulation. Here we show that hypoxia and the stress hormones PGE2 and glucocorticoid interact in complex ways in osteoblasts, converging on insulin like growth factor I (IGF-I) expression. Whereas hypoxia alone rapidly increased transcription factor HIF activity, it suppressed DNA synthesis, had no significant effects on protein synthesis or alkaline phosphatase activity, and drove discrete changes in a panel of osteoblast mRNAs. Notably, hypoxia increased expression of the acute phase response transcription factor C/EBPδ which can induce IGF-I in response to PGE2, but conversely prevented the stimulatory effect of PGE2 on IGF-I mRNA. However, unlike its effect on C/EBPδ, hypoxia suppressed expression of the obligate osteoblast transcription factor Runx2, which can activate an upstream response element in the IGF-I gene promoter. Hypoxic inhibition of IGF-I and Runx2 were enforced by glucocorticoid, and continued with prolonged exposure. Our studies thus reveal that IGF-I expression is stratified by two critical transcriptional elements in osteoblasts, which are resolved by the individual and combined effects of hypoxic stress and stress hormones. In so doing, hypoxia suppresses Runx2, limits the enhancing influence of PGE2, and interacts with glucocorticoid to reduce IGF-I expression by osteoblasts.

The mouse retina in 3D: quantification of vascular growth and remodeling

The mouse retina has become a prominent model for studying angiogenesis. The easy access and well-known developmental progression have significantly propelled our ability to examine and manipulate blood vessels in vivo. Nonetheless, most studies have restricted their evaluations to the superficial plexus (an upper vascular layer in contact with the vitreous). Here we present experimental data and quantification for the developmental progression of the full retina including the intermediate and deeper plexus that sprouts from the superficial layer. We analyze the origin and advancement of vertical sprouting and present the progression of vascular perfusion within the tissue. Furthermore, we introduce the use of Minkowsky functionals to quantify remodeling in the superficial and deeper plexus. The work expands information on the retina towards a 3D structure. This is of particular interest, as recent data have demonstrated differential effects of gene deletion on the upper and deeper plexus, highlighting the concept of distinct operational pathways during sprouting angiogenesis.

A murine model for retinopathy of prematurity identifies endothelial cell proliferation as a potential mechanism for plus disease

PURPOSE

To characterize the features and possible mechanism of plus disease in the mouse oxygen-induced retinopathy (OIR) model for retinopathy of prematurity.

METHODS

Wild-type and Adam (A Disintegrin And Metalloproteinase) knockout mice were exposed to 75% oxygen from postnatal day 7 to 12 (P7 to P12) (hyperoxia), then returned to normal air (relative hypoxia). Live fundus imaging and fluorescein angiography at P17 were compared to immunofluorescence analysis of flat-mounted retinas. Two hallmarks of plus disease, arterial tortuosity and venous dilation, were analyzed on fixed retinas (P12-P17). The length of tortuous vessels was compared to a straight line between two points; the diameter of retinal vessels was determined using ImageJ software, and bromo-deoxyuridine (BrdU) labeling was used to visualize proliferation of retinal vascular cells.

RESULTS

Mice developed retinal arterial tortuosity and venous dilation after exposure to OIR, which was visible in live fundus images and fixed whole-mounted retinas. Vein dilation, arterial tortuosity, and BrdU incorporation gradually increased over time. Moreover, Adam8(-/-) and Adam9(-/-) mice and mice lacking Adam10 in endothelial cells were partially protected from plus disease compared to controls.

CONCLUSIONS

The mouse OIR model can be used to study the pathogenesis of plus disease and identify potential therapeutic targets. The severity of plus disease increases over time following OIR and correlates with increased proliferation of endothelial cells, suggesting that proliferation of vascular cells may be a mechanism underlying the development of plus disease. Moreover, our findings suggest that ADAMs 8, 9, and 10 could be targets for treatment of plus disease.

Capillary-free vascularized retina in patients with aggressive posterior retinopathy of prematurity and late retinal capillary formation

Purpose

To report the clinical features, clinical course, and treatment outcomes after laser photocoagulation in infants with aggressive posterior retinopathy of prematurity (APROP) and capillary-free zones in vascularized retina.

Methods

Six patients (12 eyes) with APROP and capillary-free zones in vascularized retina were retrospectively reviewed. Twelve eyes of six infants were included and were treated with laser photocoagulation for avascular retina and for capillary-free zones in vascularized retina, except for the posterior pole, and fundus findings were photographically-documented in sequence. In addition, anatomic and visual outcomes were evaluated with complications of APROP.

Results

Among all of the consecutive infants with APROP, capillary-free zones in vascularized retina were demonstrated in 24% of the infants. All of the infants were >27 weeks of gestation age and had birth weights >1,000 g. After laser treatment, 7 eyes (58.3%) had favorable outcomes, and late capillary filling in capillary-free zones of vascularized retina were noted, however 4 eyes (33.3%) progressed to retinal detachment and 1 eye (8.3%) was complicated by a retinal fold-distorting posterior pole. The visual outcomes were associated with anatomic outcomes.

Conclusions

The anatomic outcomes in infants with APROP who had capillary-free zones were comparable to previously reported infants with APROP. The late capillary filling of capillary-free zones in vascularized retina was noted, and angiogenesis was considered to be involved. This process toward normal capillary formation or neovascularization in APROP, might determine its outcome.

Involvement of CD24 in angiogenesis in a mouse model of oxygen-induced retinopathy

PURPOSE

To investigate a possible involvement of CD24 in vascular remodeling and angiogenesis in retinopathy of prematurity (ROP) in a mouse model of oxygen-induced retinopathy.

MATERIALS AND METHODS

17 CD24 knockout (KO) and 12 wild-type (WT) C57BL/6 mice were used. Group 1 mice were exposed to oxygen concentrations of 75 ± 2% from postnatal day (P) 7 to P12. Group 2 mice were raised in room air. At P17, all mice underwent fluorescein-conjugated-dextran perfusion and were sacrificed. The flat-mounted retinas were scored manually and digitally by a new computerized algorithm, according to blood vessel obliteration, tortuosity, vascular tufts and neovascularization formation.

RESULTS

Fifty four retinal whole mounts were available for analysis and scoring. Group 1 retinas had significantly higher values of vaso-obliteration, tufts, neovascularization, vessel tortuosity and higher mean retinopathy scores than Group 2 retinas (KO mice: 9.0 ± 0.27 vs. 0.74 ± 0.2, respectively, P < 0.0001; WT mice: 7.58 ± 0.40 vs. 1.17 ± 0.27, respectively, P < 0.0001). Manual scoring in Group 1 revealed higher values of neovascularization, tortuosity and mean retinopathy scores in KO mice vs. WT mice (9.0 ± 0.27 vs. 7.58 ± 0.40, respectively, P = 0.009). Digital scoring revealed a higher neovascularization score in KO mice as well (13.72 ± 0.82% vs. 8.06 ± 0.27%, P < 0.0001). All mice had similar vaso-obliteration areas. There were no significant differences between KO and WT mice in Group 2.

CONCLUSIONS

Absence of CD24 may have a deleterious effect on angiogenesis occurring in the second stage of ROP development, though its role in vessel obliteration during the first stage of ROP is probably limited.

Ocular medicines in children: the regulatory situation related to clinical research

Background

Many ocular medications are prescribed for paediatric patients, but the evidence for their rational use is very scant. This study was planned to compare the availability and the licensing status of ocular medications marketed in Italy, the United Kingdom (UK), and the United States of America (USA) related to the amount of published and un-published RCTs testing these drugs in the paediatric population.

Methods

A quantitative analysis was performed to evaluate the number of ocular medications with a paediatric license in Italy, the UK, and the USA. A literature search was also performed in MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials for randomized controlled trials (RCTs) on ophthalmic pharmacological therapy in children aged < 18 years, published up to December 2010. A search in the international clinical trial registries, the list of paediatric investigation plans (PIPs) approved by European Medicines Agency (EMA), and the table of medicines with new paediatric information approved by Food and Drug Administration (FDA) was also performed.

Results

In all, of 197 drugs identified, 68 (35%) single drugs are licensed for paediatric use at least in one considered country, while 23 (12%) were marketed in all three countries. More specifically, in Italy 43 single drugs (48% of those marketed) had a paediatric license, while 39 (64%) did in the UK and 22 (54%) did in the USA. Only 13 drugs were marketed with a paediatric license in all countries.

The percentage of drugs licensed for paediatric use and for which at least one RCT had been performed ranged between 51% in Italy and 55% in the USA. No published RCTs were found for 11 (48%) drugs licensed for paediatric use in all three countries. In all, 74 (35%) of the retrieved RCTs involved mydriatic/cycloplegic medications.

A total of 62 RCTs (56% completed) on 46 drugs were found in the international clinical trial registries. Cyclosporin and bevacizumab were being studied in many ongoing trials. Twenty-six drugs had new paediatric information approved by FDA based on new paediatric clinical trials, while only 4 PIPs were approved by EMA.

Conclusions

There is a pressing need for further research and clinical development in the pediatric ophthalmic area, where effective up-to-date treatments, and additional research and education on use in children, remain priorities.

Laser treatment for retinopathy of prematurity

Retinal development involves a complex coordination of events that may be affected by premature delivery, leading to retinopathy of prematurity (ROP), a potential blinding childhood disease. The avascular retina drives further disease progression, with laser ablation reducing unfavorable anatomic outcomes as well as maintaining visual acuity. Trials have stressed the importance of early identification and treatment of threshold and high-risk prethreshold disease to improve outcomes. Retinal ablation with laser photocoagulation should involve entire treatment of avascular retina with a confluent laser spot density, avoiding skip lesions. The current review highlights the use of laser photocoagulation in the treatment of ROP.

Efficacy of intravitreal captopril on oxygen-induced retinopathy in mice

AIM

To study the inhibitory effect of intravitreal captopril on oxygen-induced retinopathy (OIR) in mice.

METHODS

Eighty postnatal day (P)7 C57BL/6J mice were randomly divided into treated group and control group with forty mice in each group. The mice were exposed to 75% ± 2% oxygen for 5 days (P7-P11) and then returned to room air for 5 days (P12-P17) to induce retinal neovascularization (RNV). Beginning on P12, the mice in treated group received daily intravitreal injections of captopril (3.0mL/kg), while those in control group received daily intravitreal injections of phosphate-buffered saline (PBS) (3.0mL/kg) through P17. After anesthetized at P17, one eye was chosen randomly as experimental eye and were enucleated. RNV was examined by Adenosine diphosphate-ase (ADPase) stained retina flat-mounts and was quantitated histologically by counting the neovascular endothelial cell nuclei anterior to inner limiting membrane (ILM). The expressions of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF) were measured by immunohistochemical method.

RESULTS

Comparing with control group, more regular distributions, better branch and reduced density of RNV were observed in eyes of treated group. The number of neovascular cell nuclei was less in treated group than that in control group (t=6.135, P<0.01). Stain of MMP-2 and VEGF was weaker in treated group than that in control group.

CONCLUSION

The results indicate that captopril can significantly inhibit RNV in OIR mice.

Hypoxia-inducible factor-1 drives annexin A2 system-mediated perivascular fibrin clearance in oxygen-induced retinopathy in mice

Oxygen-induced retinopathy (OIR) is a well-characterized model for retinopathy of prematurity, a disorder that results from rapid microvascular proliferation after exposure of the retina to high oxygen levels. Here, we report that the proliferative phase of OIR requires transcriptional induction of the annexin A2 (A2) gene through the direct action of the hypoxia-inducible factor-1 complex. We show, in addition, that A2 stabilizes its binding partner, p11, and promotes OIR-related angiogenesis by enabling clearance of perivascular fibrin. Adenoviral-mediated restoration of A2 expression restores neovascularization in the oxygen-primed Anxa2(-/-) retina and reinstates plasmin generation and directed migration in cultured Anxa2(-/-) endothelial cells. Systemic depletion of fibrin repairs the neovascular response to high oxygen treatment in the Anxa2(-/-) retina, whereas inhibition of plasminogen activation dampens angiogenesis under the same conditions. These findings show that the A2 system enables retinal neoangiogenesis in OIR by enhancing perivascular activation of plasmin and remodeling of fibrin. These data suggest new potential approaches to retinal angiogenic disorders on the basis of modulation of perivascular fibrinolysis.

Hyperglycemia, insulin and slower growth velocity may increase the risk of retinopathy of prematurity

OBJECTIVE

Strategies to reduce Retinopathy of Prematurity (ROP) have focused primarily on respiratory management. Hyperglycemia (HG) and insulin use, risk factors for adult diabetic retinopathy, as well as growth rates may be modifiable variables useful to reduce ROP.

STUDY DESIGN

This was a retrospective chart review of all infants born at <30 weeks gestation from 2003 to 2007 who survived to discharge in our neonatal intensive care unit (NICU). All whole-blood glucose values (BG in mg dl(-1)) done in the first 29 days of life were collected for analysis.

RESULT

BGs were done at least every 3 to 6 h for the first 48 to 96 h of life, then every 6 to 24 h thereafter, as long as infants remained on hyperalimentation. Hyperglycemia was defined as mild (BG 151 to 180), moderate (181 to 210) or severe (>210). Insulin use (given if BG>180 to 210) was also noted for each simultaneous BG. ROP was classified as none, mild (stage 1 to 2) or severe (stage 3 to 4). Growth velocity (g kg(-1) per day), length and head circumference were also analyzed. In all, 372 infants mean (s.d.) gestational age 27.6 (1.4) weeks, mean (s.d.) birth weight 994 (242)g had 18,649 BGs analyzed. 103 (28%) of the infants had mild ROP and 29 (8%) had severe ROP. 137 (37%) of the infants received at least 1 day of exogenous insulin (median days 9, range 1 to 26). Higher cumulative mean BG, more episodes of HG, and more insulin exposure were associated with an increased incidence and severity of ROP. Ordinal logistic regression identified lower gestational age, male gender, fetal growth restriction, slower NICU growth velocity, and higher BG as predictors for severity of ROP. However, insulin use was a stronger predictor than BG, and replaced it in the risk model.

CONCLUSION

After adjusting for important risk factors, HG and especially insulin use in premature infants may increase the risk of ROP. In addition, slower NICU growth velocity, but not rates of head or length growth, was predictive of ROP.

How to overcome retinal neuropathy: the fight against angiogenesis-related blindness

The retina consists of neuronal cells of high metabolic activity that are supplied by an abundant vasculature. It is a main theme of ophthalmologic research, because retinopathies are common causes of blindness in all age groups: age-related macular degeneration in the elderly, diabetic retinopathy in the middle aged, and retinopathy of prematurity and retinoblastoma in children. Interestingly, angiogenesis underlies the pathogenesis of all these diseases, and breakdown of the blood-retinal barrier is also thought to play an important role before and throughout the process of new vessel formation. However, so far, most treatments have targeted angiogenesis only, especially vascular endothelial growth factor. Consideration of the restoration of the blood-retinal barrier should be required. In this review, we discuss the clinical manifestation, pathogenesis, and current treatment options for angiogenesis-related blindness. In addition, because of the recent introduction of novel strategies, we describe pathogenesis-based treatment options to treat angiogenesis-related blindness.

[Early administration of erythropoietin in the extreme premature, a risk factor for retinopathy of prematurity?]

INTRODUCTION

Erythropoietin (EPO) stimulates angiogenesis and may favour the appearance of retinopathy of prematurity (ROP). The objective was to determine if EPO+Fe administered from the 5th day of life could be an independent risk factor for ROP appearance and its severity.

PATIENTS AND METHOD

The study included 718 preterm newborns with a birth weight ≤1,500g or a gestational age ≤32 weeks (and 6 days), admitted between 2001 and 2008. During these years, the target SaO₂ was between 88% and 93%. EPO treatment began at 5-7 days of life, with a dose of 250 UI/Kg, 3 times a week, subcutaneously, together with Fe, 5-6mg/kg/day, both until 34 weeks of corrected age or discharge.

RESULTS

A total of 493 preterms (68.7%) did not have ROP, 139 (19.4%) had a grade 1 ROP, 50 (7.0%) a grade 2 ROP and 36 (5.0%) a grade 3 ROP. Laser therapy was required by 27 severe ROP was associated with lower birth weight and gestational age, more neonatal morbidity and a more aggressive treatment (duration of oxygen supplements or mechanical ventilation, number of blood transfusions). Risk factors independently and significantly associated with any ROP grade were: lower birth weight, no caesarean section, EPO administration and need for blood transfusion. EPO administration increased the risk of ROP by 2.4, but this only happened in case of grade 1 ROP (OR: 5.50).

CONCLUSIONS

EPO+Fe administration is associated and perhaps stimulates the appearance of grade 1 ROP.

The mouse retina as an angiogenesis model

The mouse retina has been used extensively over the past decades to study both physiologic and pathologic angiogenesis. Over time, various mouse retina models have evolved into well-characterized and robust tools for in vivo angiogenesis research. This article is a review of the angiogenic development of the mouse retina and a discussion of some of the most widely used vascular disease models. From the multitude of studies performed in the mouse retina, a selection of representative works is discussed in more detail regarding their role in advancing the understanding of both the ocular and general mechanisms of angiogenesis.

Retinal protective effects of resveratrol via modulation of nitric oxide synthase on oxygen-induced retinopathy

Purpose

Retinopathy of prematurity (ROP) is one of the leading causes of blindness, with retinal detachment occurring due to oxygen toxicity in preterm infants. Recently, advances in neonatal care have led to improved survival rates for preterm infants, and ROP has increased in incidence. In the present study, we aimed to determine whether or not resveratrol exhibits protective effects in an animal model of ROP and in primary retinal cell cultures of neonatal rat via nitric oxide (NO)-modulating actions using western blotting and real-time PCR with inducible nitric oxide synthase (iNOS), endothelial NOS (eNOS) and neuronal NOS (nNOS) antibodies and mRNAs.

Methods

In an in vivo oxygen-induced retinopathy (OIR) model, cyclic hyperoxia was induced with 80% O₂ for one day and 21% O₂ for one day from P1 to P14 in newborn Sprague-Dawley (SD) rats. Resveratrol was injected intravitreally for seven days and rats were sacrificed at P21. In vitro OIR primary retinal cell culture was performed using P0-2 SD rats. Hyperoxia injuries were induced through 100% O₂ exposure for six hours. Western blotting and real-time PCR using iNOS, eNOS, nNOS antibodies and primers were performed in the rat model of ROP and the dispersed retinal cell culture.

Results

In both in vivo and in vitro OIR, the expression of iNOS antibody and mRNA was increased and of eNOS and nNOS were reduced in the resveratrol-treated group.

Conclusions

In conclusion, resveratrol appeared to exert retinal protective effects via modulation of NO-mediated mechanism in in vivo and in vitro OIR models.