Long-term neuroprotective effect of erythropoietin on executive functions in very preterm children (EpoKids): protocol of a prospective follow-up study

The Effect of Perinatal High-Dose Erythropoietin on Retinal Structural and Vascular Characteristics in Children Born Preterm

PURPOSE

To study the long-term effects of perinatal high-dose recombinant human erythropoietin (rhEPO) on macular structural and vascular development in preterm children.

DESIGN

Randomized, double-blind clinical trial follow-up plus cohort study.

METHODS

Setting: Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.

STUDY POPULATION

extremely or very preterm born children aged 7-15 years from an ongoing neuropediatric study (EpoKids). These had been previously randomized to receive either high-dose rhEPO or placebo perinatally.

INCLUSION CRITERIA

participation in the EpoKids Study, written informed consent (IC).

EXCLUSION CRITERIA

previous ocular trauma or surgery; retinal or developmental disease unrelated to prematurity. Term-born children of comparable age were enrolled as a healthy control (HC) group.

INCLUSION CRITERIA

term birth, IC.

EXCLUSION CRITERIA

any ocular or visual abnormality, high refractive error. Examiners were blinded regarding intervention status until completion of all analyses. (Participants/guardians remain blinded).

OBSERVATION PROCEDURES

Spectral-domain OCT scans (Heidelberg Spectralis system) and OCTA imaging (Zeiss PlexElite 9000) were obtained. Ophthalmological and orthoptic examinations excluded ocular comorbidities.

MAIN OUTCOME MEASURES

OCT (central retinal thickness, CRT; total macular volume, TMV), superficial plexus OCTA (foveal avascular zone, FAZ; vessel density, VD; vessel length density, VLD) parameters and foveal hypoplasia grade according to published criteria.

RESULTS

Macular vessel density parameters (VD and VLD) were significantly lower (p =0.015, CI-95: 0.01 to 0.06 and p=0.015, CI-95: 0.74 to 3.64) in the EPO group (n= 52) when compared to placebo (n=35). No other significant differences were observed between the EPO and placebo group. When comparing the intervention subgroups to HC we found six significant differences in OCT and OCTA parameters (FAZ, VD, VLD and CRT comparing HC and EPO group; FAZ and CRT when comparing HC and placebo group).

CONCLUSIONS

Early high-dose rhEPO in infants born extremely or very preterm affects macular vessel density parameters compared to placebo. Premature birth (regardless of intervention status) affects retinal structure and vascular development. Our findings on macular vascular development do not contraindicate the administration of early high-dose EPO in preterm infants. For further understanding of the role of EPO on macular development and its clinical significance, future studies are needed.

The Effect of High-Dose Erythropoietin Perinatally on Retinal Function in School-Aged Children Born Extremely or Very Preterm

PURPOSE

To investigate the long-term effects of high-dose recombinant human erythropoietin (rhEPO) administered during the perinatal period on retinal and visual function in children born extremely or very preterm.

DESIGN

Randomized, double-blind clinical trial follow-up plus cohort study.

METHODS

 Setting: Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.

STUDY POPULATION

Extremely or very preterm-born children aged 7 to 15 years, previously randomized to receive either high-dose rhEPO or placebo in the perinatal period.

INCLUSION CRITERIA

participation in an ongoing neuropediatric study (EpoKids), written informed consent.

EXCLUSION CRITERIA

previous ocular trauma or surgery; retinal or developmental disease unrelated to prematurity. Healthy control (HC) children of comparable age were recruited.

INCLUSION CRITERIA

term birth, informed consent.

EXCLUSION CRITERIA

any ocular/visual abnormality, high refractive error. Intervention status (rhEPO/placebo) was unknown to examiners and subjects at examination, with examiners unblinded only after completion of all analyses.

OBSERVATION PROCEDURES

The electroretinogram (ERG) was performed with the RETeval device (LKC Technologies, Inc). Ophthalmological and orthoptic examinations excluded comorbidity in the prematurely born cohort and ocular diseases in the HC group.

MAIN OUTCOME MEASURES

Scotopic and photopic ERG response amplitudes and peak times (6 amplitudes; 6 peak times). Secondary outcomes were habitual visual acuity and color discrimination performance (for descriptive summary only).

RESULTS

No differences in ERG parameters between EPO (n = 52; 104 eyes) and placebo (n = 35; 70 eyes) subgroups were observed (all corrected P > .05). Two cone system-mediated peak times were slightly slower in the placebo than HC (n = 52; 104 eyes) subgroup (coefficient/95% confidence interval = 0.53/0.21-0.85 and 0.36/0.13-0.60; P = .012 and .022); a predominantly rod system-mediated peak time was slightly faster in the EPO than the HC subgroup (coefficient/95% confidence interval = -4.33/-6.88 to -1.78; P = .011). Secondary outcomes were comparable across subgroups.

CONCLUSIONS

Administration of high-dose rhEPO to infants born extremely or very preterm during the perinatal period has no measurable effects on retinal function in childhood compared to placebo. Premature birth may cause small, likely clinically insignificant effects on retinal function in childhood, which may be partially mitigated by administration of rhEPO during the perinatal period.

Early High-Dose Erythropoietin and Cognitive Functions of School-Aged Children Born Very Preterm

Importance

Children born very preterm are at risk for long-term neurodevelopmental sequelae. Prophylactic high-dose recombinant human erythropoietin (rhEpo) shortly after birth has not been shown to improve cognitive, motor, and behavioral development at 2 and 5 years.

Objective

To investigate whether early high-dose rhEpo is associated with better executive functions and processing speed-late-maturing cognitive functions-in school-aged children born very preterm.

Design, Setting, and Participants

This single-center cohort study was a prospective, observational follow-up study of a multicenter neonatal clinical trial; 365 children born very preterm (mean gestational age, 29.3 weeks [range, 26.0-31.9 weeks]) who had been enrolled in the Swiss EPO Neuroprotection Trial at birth between 2005 and 2012, and who were included in the primary outcome analyses at 2 years, were eligible to be recruited for the EpoKids study between 2017 and 2021 when they were at school age. Term-born children were additionally recruited and included in a control group. Data were analyzed between May and September 2022.

Exposure

Administration of rhEpo (3000 IU/kg) or placebo (saline, 0.9%) intravenously 3 times within the first 2 days of life as part of the Swiss EPO Neuroprotection Trial.

Main Outcome and Measures

A comprehensive neuropsychological test battery assessed executive functions and processing speed, and parents reported on their child's executive functions in everyday life to test the hypothesis that early high-dose rhEpo administration is associated with better cognitive outcomes at school age.

Results

In the EpoKids study, 214 children born very preterm (58.6% of 365 children in eligible cohort) were assessed at a mean age of 10.4 years (range, 6.9-13.4 years); 117 (54.7%) were boys. There was no evidence that the 117 children who had received rhEpo differed from the 97 children who had received placebo in any of the 15 executive function and processing speed tests, nor in parent-rated executive functions (estimates ranged from -0.138 to 0.084, all 95% CIs included 0). Irrespective of rhEpo or placebo allocation, children born very preterm scored lower on 11 of 15 executive function and processing speed tests than term-born peers (estimates ranged from 0.112 to 0.255, 95% CIs did not include 0).

Conclusion and Relevance

This study found no evidence for a positive association between prophylactic early high-dose rhEpo administration and long-term neurodevelopmental outcomes after very preterm birth. These results suggest that a comprehensive approach, including pharmacological and nonpharmacological prevention and intervention strategies, is needed to support these children's neurodevelopmental outcome.

Inhibition abilities and functional brain connectivity in school-aged term-born and preterm-born children

BACKGROUND

Inhibition abilities are known to have impact on self-regulation, behavior, and academic success, and they are frequently impaired in children born preterm. We investigated the possible contributions of resting-state functional brain connectivity to inhibition following preterm birth.

METHODS

Forty-four preterm and 59 term-born participants aged 8-13 years were administered two inhibition tasks and resting-state functional MRI was performed. Functional connectivity (FC) networks were compared between groups using network-based statistics. Associations of FCNs and inhibition abilities were investigated through multivariate linear regression models accounting for the interaction between birth status and inhibition.

RESULTS

NBS revealed weaker FC in children born preterm compared to term-born peers in connections between motor and supplementary motor regions, frontal lobe, precuneus, and insula. Irrespective of birth status, connections between the cerebellum, frontal, and occipital lobes and inter-lobar, subcortical, intra-hemispheric long-range connections were positively correlated with one of the two inhibition tasks.

CONCLUSIONS

Preterm birth results in long-term alterations of FC at network level but these FCN alterations do not specifically account for inhibition problems in children born very preterm.

IMPACT

Irrespective of birth status, significant associations were found between the subdomain of response inhibition and functional connectivity in some subnetworks. A group comparisons of functional brain connectivity measured by rsfMRI in school-aged children born very preterm and at term. The investigation of network-level functional connectivity at rest does not appear adequate to explain differences in inhibition abilities between children born very preterm and at term, hence other imaging techniques might be more suited to explore the underlying neural mechanisms of inhibition abilities in school-aged children born very preterm.

Retinopathy of prematurity protection conferred by uteroplacental insufficiency through erythropoietin signaling in an experimental Murine Model

BACKGROUND

Recent clinical studies suggest that preeclampsia, characterized by uteroplacental insufficiency (UPI) and infant intrauterine growth restriction (IUGR), may be protective against retinopathy of prematurity (ROP) in preterm infants. Experimental models of UPI/IUGR have found an association of erythropoietin (EPO) with less severe oxygen-induced retinopathy (OIR); however, it is unclear if EPO/EPO receptor (EPOR) signaling was involved. We hypothesized that maternal UPI and resultant infant IUGR would protect against features of ROP through EPO/EPOR signaling.

METHODS

We compared transgenic mice with hypoactive EPOR signaling (hWtEPOR) to littermate wild-type mice (mWtEpoR) in a novel combined model of IUGR and ROP. Thromboxane A2 (TXA2) was infused into pregnant C57Bl/6J dams to produce UPI/IUGR; postnatal pups and their foster dams were subjected to a murine OIR model.

RESULTS

Following hyperoxia, hematocrits were similar between littermate wild-type (mWtEpoR) TXA2/OIR and vehicle/OIR pups. mWtEpoR TXA2/OIR had increased serum EPO, retinal EPO and VEGF, and decreased avascular retinal area (AVA) compared to vehicle/OIR pups. In comparison to the mWtEpoR TXA2/OIR pups, AVA was not reduced in hWtEPOR TXA2/OIR pups.

CONCLUSION

Our findings provide biologic evidence that UPI/OIR-induced endogenous EPOR signaling confers protection against hyperoxia-induced vascular damage that may be related to pathophysiology in ROP.

IMPACT

Maternal preeclampsia and infant growth restriction confer retinovascular protection against high oxygen-induced damage through endogenous erythropoietin signaling.

Effect of Early High-Dose Recombinant Human Erythropoietin on Behavior and Quality of Life in Children Aged 5 Years Born Very Preterm: Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

In light of the promising neuroprotective properties of recombinant human erythropoietin (RHEpo), the Swiss EPO Neuroprotection Trial was started to investigate its effect on neurodevelopment in very preterm infants. The results of the primary and secondary outcome analysis did not show any effect of RHEpo on cognitive performance, neuromotor outcomes, or somatic growth of the study participants at ages 2 or 5 years.

OBJECTIVE

To investigate whether early high-dose RHEpo improves behavioral outcomes and health-related quality of life (HRQoL) at age 5 years.

DESIGN, SETTING, AND PARTICIPANTS

This was a prespecified secondary analysis of the double-blind, placebo-controlled, multicenter Swiss EPO Neuroprotection randomized clinical trial, which was conducted at 5 level-III perinatal centers in Switzerland. Infants born between 26 weeks 0 days' and 31 weeks 6 days' gestation were recruited between 2005 and 2012 and followed-up until age 5 years (last follow-up in 2018). Data were analyzed from January 6 to December 31, 2021.

INTERVENTIONS

Infants were assigned to receive either RHEpo (3000 IU/kg) or placebo (saline, 0.9%) intravenously 3 times within the first 42 hours after birth.

MAIN OUTCOMES AND MEASURES

The prespecified parent-reported measures of behavioral outcomes and health-related quality of life (HRQoL) of their children at the age of 5 years were assessed by two standardized questionnaires: the Strengths and Difficulties Questionnaire (behavioral outcomes) and the KIDSCREEN-27 (HRQoL).

RESULTS

Among 448 randomized infants, 228 infants were assigned to the RHEpo group and 220 infants were assigned to the placebo group. Questionnaire data were available for 317 children (71%) at a mean (SD) age of 5.8 (0.4) years (mean [SD] gestational age at birth, 29.3 [1.6] weeks; mean [SD] birth weight 1220 [340] grams; 128 [40%] female infants). At the age 5 years follow-up, the mean (SD) total difficulties score in the RHEpo group (8.41 [5.60] points) was similar to that of the placebo group (7.76 [4.81]) (P = .37). There were no statistically significant differences between the groups in any other outcome measures.

CONCLUSIONS AND RELEVANCE

This secondary analysis of a randomized clinical trial showed no evidence for an effect of early high-dose RHEpo administration on behavioral outcomes or HRQoL in children born very preterm at early school age.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00413946.

Prenatal and postnatal insults differentially contribute to executive function and cognition: Utilizing touchscreen technology for perinatal brain injury research

The use of touchscreen technology to evaluate cognitive deficits in animal models has grown tremendously over the past 20 years. The touchscreen apparatus encompasses many advantages, namely a high level of standardization and translational capability. Improvements in technology in recent years have expanded the versatility of the touchscreen platform, as it is able to test distinct cognitive modalities including working memory, attention, discrimination, and association. Importantly, touchscreen technology has allowed researchers to explore deficits in multiple pillars of cognition in a wide variety of perinatal disorders with neurological sequelae across critical developmental windows. The touchscreen platform has been used to dissect deficits in antenatal CNS injury including fetal alcohol syndrome, prenatal opioid exposure, and chorioamnionitis, to peripartum insults such as term hypoxic-ischemic encephalopathy, to early postnatal insults including infantile traumatic brain injury. Most importantly, touchscreen technology offers the sensitivity necessary to detect subtle injury and treatment-induced changes in cognition and executive function beyond those offered by more rudimentary tests of rodent cognition. Understanding the pathophysiology of these disorders in rodents is paramount to addressing these deficits in human infants and dissecting the neural circuitry essential to perinatal brain injury pathophysiology and responsiveness to novel therapeutics. Touchscreen testing provides an effective, facile, sophisticated technique to accelerate the goal of improving cognitive and behavioral outcomes of children who suffer perinatal brain injury.

Mental sequelae of the COVID-19 pandemic in children with and without complex medical histories and their parents: well-being prior to the outbreak and at four time-points throughout 2020 and 2021

The objective of this study is to understand the long-term mental sequelae for families over the course of the COVID-19 pandemic by longitudinally investigating the well-being of children with and without complex medical histories and their parents. Well-being of 200 children (between 7 and 18 years of age; 73 typically developing, 46 born very preterm, 73 with complex congenital heart disease) and 175 of their parents was assessed prior to and during the first (April-May 2020), second (October-November 2020), third (April-May 2021), and fourth wave (October-November 2021) of the pandemic with standardized questionnaires. Linear mixed models were used to investigate longitudinal changes in child and parent well-being compared to before the pandemic. Social and COVID-19-specific determinants were investigated as predictors of impaired well-being. To illustrate clinical relevance, the proportion of children and parents scoring > 1 SD below normative mean/median was reported. Compared to before the pandemic, child proxy-reported well-being was lower during the first but not the second, third, and fourth waves. Child self-reported well-being was not lower during the pandemic compared to before. Parent well-being dropped during the first wave and remained low throughout the subsequent waves. Proxy-reported child and self-reported parent well-being was lower in families with sparse social support and poor family functioning. Parents of typically developing children reported lower well-being than parents of children born very preterm or with a complex congenital heart disease. In November 2021, 20% of children (both self- and proxy-report) and 24% of parents scored below the normal range compared to 11% (child self-report), 10% (child proxy-report), and 16% (parent self-report), respectively, before the pandemic. The pandemic continues to impact the well-being of parents of school-aged children with and without complex medical histories more than 1 year after its outbreak. Children's well-being was specifically affected during the first wave of the pandemic and has recovered thereafter. Families with sparse social support and poor family functioning are particularly at risk for compromised well-being and support should be provided to them.

Pharmacological Neuroprotection of the Preterm Brain: Current Evidence and Perspectives

Despite improvements in viability, the long-term neurodevelopmental outcomes of preterm babies remain serious concern as a significant percentage of these infants develop neurological and/or intellectual impairment, and they are also at increased risk of psychiatric illnesses later in life. The current challenge is to develop neuroprotective approaches to improve adverse outcomes in preterm survivors. The purpose of this review was to provide an overview of the current evidence on pharmacological agents targeting the neuroprotection of the preterm brain. Among them, magnesium sulfate, given antenatally to pregnant women with imminent preterm birth before 30 to 34 weeks of gestation, as well as caffeine administered to preterm infants after birth, exhibited neuroprotective effects for human preterm brain. Erythropoietin treatment of preterm infants did not result in neuroprotection at 2 years of age in two out of three published large randomized controlled trials; however, long-term follow-up of these infants is needed to come to definite conclusions. Further studies are also required to assess whether melatonin, neurosteroids, inhaled nitric oxide, allopurinol, or dietary supplements (omega-3 fatty acids, choline, curcumin, etc.) could be implemented as neuroprotectants in clinical practice. Furthermore, other pharmacological agents showing promising signs of neuroprotective efficacy in preclinical studies (growth factors, hyaluronidase inhibitors or treatment, antidiabetic drugs, cannabidiol, histamine-H3 receptor antagonists, etc.), as well as stem cell- or exosomal-based therapies and nanomedicine, may prove useful in the future as potential neuroprotective approaches for human preterm brain. KEY POINTS: · Magnesium and caffeine have neuroprotective effects for the preterm brain.. · Follow-up of infants treated with erythropoietin is needed.. · Neuroprotective efficacy of several drugs in animals needs to be shown in humans..

Effects of Correcting for Prematurity on Executive Function Scores of Children Born Very Preterm at School Age

OBJECTIVE

To investigate whether correction for prematurity affects executive function scores in school-aged children born very preterm.

STUDY DESIGN

Executive functions were assessed with standardized neuropsychological tests in 142 children born very preterm (born at ≤32 weeks of gestational age or with a birth weight of ≤1500 g) and 391 control children, aged 7-13 years. Four-month age bands were established from the data of control children. Differences between uncorrected and corrected scores were compared against zero difference and between very preterm children born before and after 28 weeks of gestation. Regression models were used to compare the uncorrected and corrected scores of children born very preterm with control children.

RESULTS

For all executive functions, significant, larger-than-zero differences between uncorrected and corrected scores were apparent in children born very preterm. Mean differences ranged from 0.04 to 0.18 SDs. Weak evidence was found that the effect of age correction is more pronounced in very preterm children born before 28 weeks of gestation than in those born after 28 weeks. Differences in executive function scores between children born very preterm and control children were attenuated if scores were corrected for prematurity.

CONCLUSIONS

Test scores based on corrected rather than uncorrected age may more accurately determine the developmental stage of very preterm children's executive functions at school age. Potential consequences for clinical and research practice need to be discussed in the future.

Impact of the COVID-19 pandemic on children with and without risk for neurodevelopmental impairments

AIM

To examine how the ongoing COVID-19 pandemic impacts child well-being and family functioning, particularly among children at risk for neurodevelopmental impairments.

METHODS

Families of 73 typically developing children, 54 children born very preterm (VPT) and 73 children with congenital heart disease (CHD) from two prospective cohort studies were assessed prior to (mean age: 10.4 [SD: 1.2] years) and during (mean age: 12.8 [SD: 2.0] years) the pandemic, more specifically, in April/May 2020. Child well-being and family functioning were assessed with validated, parent-reported questionnaires and tested with linear mixed models. Group comparison of child distress and parental concerns related to medical implications of COVID-19 and homeschooling, assessed with 5-point Likert scales, was done with Mann-Whitney U tests.

RESULTS

Children's psychological well-being and family functioning (both, p < 0.001) decreased significantly during the pandemic, irrespective of group. Children with CHD were reported to be more concerned about becoming infected with SARS-CoV-2 than were others. Child distress due to homeschooling and parents' concerns about children's academic achievements were significantly higher in VPT and CHD children than in typically developing peers (all p < 0.001).

CONCLUSION

The COVID-19 pandemic substantially impacts the whole family and leads to additional distress in families with children at risk for neurodevelopmental impairments. These families should receive individualised counselling and assistance from healthcare providers and schools during the pandemic.

Signaling Through the Erythropoietin Receptor Affects Angiogenesis in Retinovascular Disease

Purpose

Exogenous erythropoietin (EPO) is being considered for tissue protection and angiogenesis in retinal vascular diseases. However, studies are limited by insufficient tools to address signaling effects through the EPO receptor (EPOR). We used a humanized mouse model of hypoactive EPOR signaling to test the hypothesis that EPOR signaling supports angiogenesis in retinovascular diseases.

Methods

Humanized Knockin EPOR mice (hWtEPOR) with hypoactive EPOR signaling were compared to littermate wild-type mice (WT). Postnatal day (p)7 mice of each genotype were exposed to 75% oxygen for five days, followed by 21% oxygen in the oxygen-induced retinopathy model (OIR) and compared to room-air (RA)–raised pups. At time points after OIR, pups were sacrificed, and flat-mounted, lectin-stained retinas were analyzed for central avascular area or intravitreal neovascular area (IVNV). Flash-frozen retinas were analyzed for angiogenic protein (Epo, VEGF, p-Stat3) and gene (Vegfa, Kdr, Epo, Hif1α, Hif2α) expression levels.

Results

In OIR, hWtEPOR mice had increased AVA compared with WT at p8, p12, and p17, but there was no difference in IVNV between hWtEPOR and WT mice at p17. Although VEGF and p-STAT3 proteins were increased in WT at p17 OIR, there were no differences in retinal angiogenic factor expression levels between hWtEPOR and WT OIR at p17 despite similar areas of IVNV.

Conclusions

Our data support the hypothesis that EPOR signaling was associated with regrowth of vascularization following oxygen-induced capillary dropout and played a role in intravitreal angiogenesis. Additional study of EPOR signaling regulation on other angiogenic factor pathways may be considered.

Repetitive Erythropoietin Treatment Improves Long-Term Neurocognitive Outcome by Attenuating Hyperoxia-Induced Hypomyelination in the Developing Brain

Introduction: Preterm infants born before 28 weeks of gestation are at high risk of neurodevelopmental impairment in later life. Cerebral white and gray matter injury is associated with adverse outcomes. High oxygen levels, often unavoidable in neonatal intensive care, have been identified as one of the main contributing factors to preterm brain injury. Thus, preventive and therapeutic strategies against hyperoxia-induced brain injury are needed. Erythropoietin (Epo) is a promising and also neuroprotective candidate due to its clinical use in infants as erythropoiesis-stimulating agent. Objective: The objective of this study was to investigate the effects of repetitive Epo treatment on the cerebral white matter and long-term motor-cognitive outcome in a neonatal rodent model of hyperoxia-induced brain injury. Methods: Three-day old Wistar rats were exposed to hyperoxia (48 h, 80% oxygen). Four doses of Epo (5,000 IU/kg body weight per day) were applied intraperitoneally from P3-P6 with the first dose at the onset of hyperoxia. Oligodendrocyte maturation and myelination were evaluated via immunohistochemistry and Western blot on P11. Motor-cognitive deficits were assessed in a battery of complex behavior tests (Open Field, Novel Object Recognition, Barnes maze) in adolescent and fully adult animals. Following behavior tests animals underwent post-mortem diffusion tensor imaging to investigate long-lasting microstructural alterations of the white matter. Results: Repetitive treatment with Epo significantly improved myelination deficits following neonatal hyperoxia at P11. Behavioral testing revealed attenuated hyperoxia-induced cognitive deficits in Epo-treated adolescent and adult rats. Conclusion: A multiple Epo dosage regimen protects the developing brain against hyperoxia-induced brain injury by improving myelination and long-term cognitive outcome. Though current clinical studies on short-term outcome of Epo-treated prematurely born children contradict our findings, long-term effects up to adulthood are still lacking. Our data support the essential need for long-term follow-up of preterm infants in current clinical trials.

Inhibition is associated with whole-brain structural brain connectivity on network level in school-aged children born very preterm and at term

Inhibition abilities are often impaired in children born very preterm. In typically-developing individuals, inhibition has been associated with structural brain connectivity (SC). As SC is frequently altered following preterm birth, this study investigated whether aberrant SC underlies inhibition deficits in school-aged children born very preterm. In a group of 67 very preterm participants aged 8-13 years and 69 term-born peers, inhibition abilities were assessed with two tasks. In a subgroup of 50 very preterm and 62 term-born participants, diffusion tensor imaging (DTI) data were collected. Using network-based statistics (NBS), mean fractional anisotropy (FA_mean) was compared between groups. Associations of FA_mean and inhibition abilities were explored through linear regression. The composite score of inhibition abilities was lower in the very preterm group (M ​= ​-0.4, SD ​= ​0.8) than in the term-born group (M ​= ​0.0, SD ​= ​0.8) but group differences were not significant when adjusting for age, sex and socio-economic status (β ​= ​-0.13, 95%-CI [-0.30, 0.04], p ​= ​0.13). In the very preterm group, FA_mean was significantly lower in a network comprising thalamo-frontal, thalamo-temporal, frontal, cerebellar and intra-hemispheric connections than in the term-born group (t ​= ​5.21, lowest p-value ​= ​0.001). Irrespective of birth status, a network comprising parietal, cerebellar and subcortical connections was positively associated with inhibition abilities (t ​= ​4.23, lowest p-value ​= ​0.02). Very preterm birth results in long-term alterations of SC at network-level. As networks underlying inhibition abilities do not overlap with those differing between the groups, FA_mean may not be adequate to explain inhibition problems in very preterm children. Future studies should combine complementary measures of brain connectivity to address neural correlates of inhibition abilities.

Erythropoietin Receptor Signaling Supports Retinal Function after Vascular Injury

The investigation of erythropoietin (EPO) has expanded to include potential nonhematopoietic roles in neural and retinal diseases, including diabetic retinopathy. However, it remains unclear how EPO functions to support the neural retina. Transgenic mice with hypoactive EPO receptor (EPOR) signaling (hWtEPOR) were compared with littermate control mice (WT) to test the role of EPOR signaling under normal conditions and after vascular injury and regrowth into the retina. Although retinal function tested with OptoMotry and electroretinography was comparable to adult (8-week-old) littermate WT mice, hWtEPOR mice had thinner inner and outer plexiform layers and a greater number of amacrine cells. Injury and repair caused by the oxygen-induced retinopathy model reduced visual acuity thresholds, reduced electroretinography amplitudes, and thinned the outer plexiform and inner nuclear layers of both WT and hWtEPOR 8-week-old mice. In hWtEPOR compared with WT mice, scotopic a-wave amplitudes were reduced by injury, despite no change in outer nuclear layer thickness; and peripheral rod, but not cone number, was reduced. Scotopic b-waves were reduced in injured hWtEPOR mice compared with WT, and rod bipolar cell ectopic neurites were increased in both genotypes after injury, suggesting a potential reparative process to preserve connectivity and the b-wave. Normal EPOR signaling appeared important because ectopic neurites and b-waves were lower in the hWtEPOR than WT injured mice.

Altered brain metabolism contributes to executive function deficits in school-aged children born very preterm

BACKGROUND

Executive function deficits in children born very preterm (VPT) have been linked to anatomical abnormalities in white matter and subcortical brain structures. This study aimed to investigate how altered brain metabolism contributes to these deficits in VPT children at school-age.

METHODS

Fifty-four VPT participants aged 8-13 years and 62 term-born peers were assessed with an executive function test battery. Brain metabolites were obtained in the frontal white matter and the basal ganglia/thalami, using proton magnetic resonance spectroscopy (MRS). N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, glutamate + glutamine (Glx)/Cr, and myo-Inositol (mI)/Cr were compared between groups and associations with executive functions were explored using linear regression.

RESULTS

In the frontal white matter, VPT showed lower Glx/Cr (mean difference: -5.91%, 95% CI [-10.50, -1.32]), higher Cho/Cr (7.39%, 95%-CI [2.68, 12.10]), and higher mI/Cr (5.41%, 95%-CI [0.18, 10.64]) while there were no differences in the basal ganglia/thalami. Lower executive functions were associated with lower frontal Glx/Cr ratios in both groups (β = 0.16, p = 0.05) and higher mI/Cr ratios in the VPT group only (interaction: β = -0.17, p = 0.02).

CONCLUSION

Long-term brain metabolite alterations in the frontal white matter may be related to executive function deficits in VPT children at school-age.

IMPACT

Very preterm birth is associated with long-term brain metabolite alterations in the frontal white matter. Such alterations may contribute to deficits in executive function abilities. Injury processes in the brain can persist for years after the initial insult. Our findings provide new insights beyond structural and functional imaging, which help to elucidate the processes involved in abnormal brain development following preterm birth. Ultimately, this may lead to earlier identification of children at risk for developing deficits and more effective interventions.