Preterm brain Injury: White matter injury

Spontaneous running wheel exercise during pregnancy prevents later neonatal-anoxia-induced somatic and neurodevelopmental alterations

Introduction

About 15-20 % of babies that suffer perinatal asphyxia die and around 25 % of the survivors exhibit permanent neural outcomes. Minimization of this global health problem has been warranted. This study investigated if the offspring of pregnant female rats allowed to spontaneously exercise on running wheels along a 11-day pregnancy period were protected for somatic and neurodevelopmental disturbs that usually follow neonatal anoxia.

Methods

spontaneous exercise was applied to female rats which were housed in cages allowing free access to running wheels along a 11-day pregnancy period. Their offspring were submitted to anoxia 24-36 h after birth. Somatic and sensory-motor development of the pups were recorded until postnatal day 21 (P21). Myelin basic protein (MBP)-stained areas of sensory and motor cortices were measured at P21. Neuronal nuclei (NeuN)-immunopositive cells and synapsin-I levels in hippocampal formation were estimated at P21 and P75.

Results

gestational exercise and / or neonatal anoxia increased the weight and the size of the pups. In addition, gestational exercise accelerated somatic and sensory-motor development of the pups and protected them against neonatal-anoxia-induced delay in development. Further, neonatal anoxia reduced MBP stained area in the secondary motor cortex and decreased hippocampal neuronal estimates and synapsin-I levels at P21; gestational exercise prevented these effects. Therefore, spontaneous exercise along pregnancy is a valuable strategy to prevent neonatal-anoxia-induced disturbs in the offspring.

Conclusion

spontaneous gestational running wheel exercise protects against neonatal anoxia-induced disturbs in the offspring, including (1) physical and neurobehavioral developmental impairments, and (2) hippocampal and cortical changes. Thus, spontaneous exercise during pregnancy may represent a valuable strategy to prevent disturbs which usually follow neonatal anoxia.

Executive and attentional functioning interventions in preterm children: a systematic review

OBJECTIVE

This systematic review, performed in accordance with the PRISMA guidelines, seeks to summarize the interventions that have been developed in order to improve executive functioning and attention in children born prematurely.

METHODS

The PICOS framework helped guide the structure and relevant terms selected for the study. Electronic systematic searches of the databases PubMed (NLM), Ovid Medline, Ovid All EBM Reviews, Ovid Embase, and Ovid PsycINFO were completed in March 2022. This review focuses on interventions that target attention and executive functioning in prematurely born children between birth and 12 years old, with outcome measures assessed between 3 and 12 years old, even if the age range in the study can exceed our own parameters. Data extraction included sample characteristics, country of recruitment, type of intervention, description of the intervention group and control group, outcome measures, and overall results. An assessment of the quality of methodology of studies was performed through an adaptation of the Downs and Black checklist for both randomized and nonrandomized studies in healthcare interventions. An assessment of the risk of bias was also presented using the Cochrane risk of bias tool for randomized trials 2.0.

RESULTS

A total of 517 premature children received an intervention at some point between birth and early adolescence. Eleven different interventions were assessed in 17 studies, with rating of the quality of methodology and outcomes ranging from lower quality studies (44% quality rating) to robust studies (96% quality rating) in terms of reporting standards, external and internal validity, and power. Five of those studies focused on interventions administered in the neonatal intensive care unit or shortly postdischarge (e.g., the Mother-Infant Transaction Program and the Newborn Individualized Developmental Care and Assessment Program, documented in two articles each [11%] or the Infant Behavioral Assessment and Intervention Program assessed in one study [about 5%]), while 12 articles reported on interventions administered between the ages of 1.5-12 years old [mostly computerized cognitive training programs such as Cogmed (23%) and BrainGame Brian (17%)]. Of the 17 articles examined, 12 (70%) showed positive short-term outcomes postintervention and 3 (17%) demonstrated positive long-term results with small to large effect sizes (0.23-2.3). Among included studies, 50% showed an overall high risk of bias, 21.4% showed some concerns, and 28.6% were low risk of bias.

CONCLUSIONS

Due to the heterogeneity of the programs reviewed, the presented findings should be interpreted as descriptive results. A careful and individualized selection from the various available interventions should be made based on the target population (i.e., age at intervention administration and outcome testing) before implementing these program protocols in clinical settings.

Early Postnatal Neuroinflammation Produces Key Features of Diffuse Brain White Matter Injury in Rats

BACKGROUND

Perinatal infection is a major risk factor for diffuse white matter injury (dWMI), which remains the most common form of neurological disability among very preterm infants. The disease primarily targets oligodendrocytes (OL) lineage cells in the white matter but also involves injury and/or dysmaturation of neurons of the gray matter. This study aimed to investigate whether neuroinflammation preferentially affects the cellular compositions of the white matter or gray matter.

METHOD

Neuroinflammation was initiated by intracerebral administration of lipopolysaccharide (LPS) to rat pups at postnatal (P) day 5, and neurobiological and behavioral outcomes were assessed between P6 and P21.

RESULTS

LPS challenge rapidly activates microglia and astrocytes, which is associated with the inhibition of OL and neuron differentiation leading to myelination deficits. Specifically, neuroinflammation reduces the immature OLs but not progenitors and causes acute axonal injury (β-amyloid precursor protein immunopositivity) and impaired dendritic maturation (reduced MAP2+ neural fiber density) in the cortical area at P7. Neuroinflammation also reduces the expression of doublecortin in the hippocampus, suggesting compromise in neurogenesis. Utilizing a battery of behavioral assessments, we found that LPS-exposed animals exhibited deficits in sensorimotor, neuromuscular, and cognitive domains.

CONCLUSION

Our overall results indicate that neuroinflammation alone in the early postnatal period can produce cardinal neuropathological features of dWMI.

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.

Potential clinical applications of advanced genomic analysis in cerebral palsy

Cerebral palsy (CP) has historically been attributed to acquired insults, but emerging research suggests that genetic variations are also important causes of CP. While microarray and whole-exome sequencing based studies have been the primary methods for establishing new CP-gene relationships and providing a genetic etiology for individual patients, the cause of their condition remains unknown for many patients with CP. Recent advancements in genomic technologies offer additional opportunities to uncover variations in human genomes, transcriptomes, and epigenomes that have previously escaped detection. In this review, we outline the use of these state-of-the-art technologies to address the molecular diagnostic challenges experienced by individuals with CP. We also explore the importance of identifying a molecular etiology whenever possible, given the potential for genomic medicine to provide opportunities to treat patients with CP in new and more precise ways.

Mild neonatal hypoxia disrupts adult hippocampal learning and memory and is associated with CK2-mediated dysregulation of synaptic calcium-activated potassium channel KCNN2

Objective

Although nearly half of preterm survivors display persistent neurobehavioral dysfunction including memory impairment without overt gray matter injury, the underlying mechanisms of neuronal or glial dysfunction, and their relationship to commonly observed cerebral white matter injury are unclear. We developed a mouse model to test the hypothesis that mild hypoxia during preterm equivalence is sufficient to persistently disrupt hippocampal neuronal maturation related to adult cellular mechanisms of learning and memory. Methods: Neonatal (P2) mice were exposed to mild hypoxia (8%O 2 ) for 30 min and evaluated for acute injury responses or survived until adulthood for assessment of learning and memory and hippocampal neurodevelopment.

Results

Neonatal mild hypoxia resulted in clinically relevant oxygen desaturation and tachycardia without bradycardia and was not accompanied by cerebral gray or white matter injury. Neonatal hypoxia exposure was sufficient to cause hippocampal learning and memory deficits and abnormal maturation of CA1 neurons that persisted into adulthood. This was accompanied by reduced hippocampal CA3-CA1 synaptic strength and LTP and reduced synaptic activity of calcium-sensitive SK2 channels, key regulators of spike timing dependent neuroplasticity, including LTP. Structural illumination microscopy revealed reduced synaptic density, but intact SK2 localization at the synapse. Persistent loss of SK2 activity was mediated by altered casein kinase 2 (CK2) signaling.

Interpretation

Clinically relevant mild hypoxic exposure in the neonatal mouse is sufficient to produce morphometric and functional disturbances in hippocampal neuronal maturation independently of white matter injury. Additionally, we describe a novel persistent mechanism of potassium channel dysregulation after neonatal hypoxia. Collectively our findings suggest an unexplored explanation for the broad spectrum of neurobehavioral, cognitive and learning disabilities that paradoxically persist into adulthood without overt gray matter injury after preterm birth.

Corpus callosum long-term biometry in very preterm children related to cognitive and motor outcomes

BACKGROUND

The corpus callosum (CC) is suggested as an indirect biomarker of white matter volume, which is often affected in preterm birth. However, diagnosing mild white matter injury is challenging.

METHODS

We studied 124 children born preterm (mean age: 8.4 ± 1.1 years), using MRI to assess CC measurements and cognitive/motor outcomes based on the Wechsler Intelligence Scale for Children-V (WPPSI-V) and Movement Assessment Battery for Children-2 (MABC-2).

RESULTS

Children with normal outcomes exhibited greater height (10.2 ± 2.1 mm vs. 9.4 ± 2.3 mm; p = 0.01) and fractional anisotropy at splenium (895[680-1000] vs 860.5[342-1000]) and total CC length (69.1 ± 4.8 mm vs. 67.3 ± 5.1 mm; p = 0.02) compared to those with adverse outcomes. All measured CC areas were smaller in the adverse outcome group. Models incorporating posterior CC measurements demonstrated the highest specificity (83.3% Sp, AUC: 0.65) for predicting neurological outcomes. CC length and splenium height were the only linear measurements associated with manual dexterity and total MABC-2 score while both the latter and genu were related with Full-Scale Intelligence Quotient.

CONCLUSIONS

CC biometry in children born very preterm at school-age is associated with outcomes and exhibits a specific subregion alteration pattern. The posterior CC may serve as an important neurodevelopmental biomarker in very preterm infants.

IMPACT

The corpus callosum has the potential to serve as a reliable and easily measurable biomarker of white matter integrity in very preterm children. Estimating diffuse white matter injury in preterm infants using conventional MRI sequences is not always conclusive. The biometry of the posterior part of the corpus callosum is associated with cognitive and certain motor outcomes at school age in children born very preterm. Length and splenium measurements seem to serve as reliable biomarkers for assessing neurological outcomes in this population.

Altered expression of transfer RNAs and their possible roles in brain white matter injury

Transfer RNAs (tRNAs) can regulate cell behavior and are associated with neurological disorders. Here, we aimed to investigate the expression levels of tRNAs in oligodendrocyte precursor cells (OPCs) and their possible roles in the regulation of brain white matter injury (WMI). Newborn Sprague-Dawley rats (postnatal day 5) were used to establish a model that mimicked neonatal brain WMI. RNA-array analysis was performed to examine the expression of tRNAs in OPCs. psRNAtarget software was used to predict target mRNAs of significantly altered tRNAs. Gene ontology (GO) and KEGG were used to analyze the pathways for target mRNAs. Eighty-nine tRNAs were changed after WMI (fold change absolute ≥1.5, P  < 0.01), with 31 downregulated and 58 upregulated. Among them, three significantly changed tRNAs were identified, with two being significantly increased (chr10.trna1314-ProTGG and chr2.trna2771-ProAGG) and one significantly decreased (chr10.trna11264-GlyTCC). Further, target mRNA prediction and GO/KEGG pathway analysis indicated that the target mRNAs of these tRNAs are mainly involved in G-protein coupled receptor signaling pathways and beta-alanine metabolism, which are both related to myelin formation. In summary, the expression of tRNAs in OPCs was significantly altered after brain WMI, suggesting that tRNAs may play important roles in regulating WMI. This improves the knowledge about WMI pathophysiology and may provide novel treatment targets for WMI.

Role of the Gut Microbiota-Brain Axis in Brain Damage in Preterm Infants

The greatest repository of microbes in the human body, the intestinal microbiome, is involved in neurological development, aging, and brain illnesses such as white matter injury (WMI) in preterm newborns. Intestinal microorganisms constitute a microbial gut-brain axis that serves as a crucial conduit for communication between the gut and the nervous system. This axis controls inflammatory cytokines, which in turn influence the differentiation of premyelinating oligodendrocytes (pre-OLs) and influence the incidence of WMI in premature newborns through the metabolites generated by gut microbes. Here, we describe the effects of white matter injury (WMI) on intestinal dysbiosis and gut dysfunction and explain the most recent research findings on the gut-brain axis in both humans and animals. We also emphasize the delicate relationship that exists between the microbiota and the brain following acute brain injury. The role that the intestinal microflora plays in influencing host metabolism, the immune system, brain health, and the course of disease is becoming increasingly clear, but there are still gaps in the field of WMI treatment. Thus, this review demonstrates the function of the gut microflora-brain axis in WMI and elucidates the possible mechanisms underlying the communication between gut bacteria and the developing brain via the gut-brain axis, potentially opening up new avenues for microbial-based intervention and treatment for preterm WMI.

A Multiplanar Radiomics Model Based on Cranial Ultrasound to Predict the White Matter Injury in Premature Infants and an Analysis of its Correlation With Neurodevelopment

OBJECTIVES

To develop and evaluate a multiplanar radiomics model based on cranial ultrasound (CUS) to predict white matter injury (WMI) in premature infants and explore its correlation with neurodevelopment.

METHODS

We retrospectively reviewed 267 premature infants. The radiomics features were extracted from five standard sections of CUS. The Spearman's correlation coefficient combined with the least absolute shrinkage and selection operator (LASSO) was applied to select features and build radiomics signature, and a multiplanar radiomics model was constructed based on the radiomics signature of five planes. The performance of the model was evaluated using the area under the receiver operating characteristic curve (AUC). Infants with WMI were re-examined by ultrasound at 2 and 4 weeks after birth, and the recovery degree of WMI was evaluated using multiplanar radiomics. The relationship between WMI and the recovery degree and neurodevelopment was analyzed.

RESULTS

The AUC of the multiplanar radiomics in the training and validation sets were 0.94 and 0.91, respectively. The neurodevelopmental function scores in infants with WMI were significantly lower than those in healthy preterm infants and full-term newborns (P < .001). There were statistically significant differences in the neurodevelopmental function scores of infants between the 2- and 4-week lesion disappearance and 4-week lesion persistence (P < .001).

CONCLUSIONS

The multiplanar radiomics model showed a good performance in predicting the WMI of premature infants. It can not only provide objective and accurate results but also dynamically monitor the degree of recovery of WMI to predict the prognosis of premature infants.

Joint observation in NICU (JOIN): A randomized controlled trial testing an early, one-session intervention during preterm care to improve perceived maternal self-efficacy and other mental health outcomes

BACKGROUND

Parents of preterm infants in the Neonatal Intensive Care Unit (NICU) environment may experience psychological distress, decreased perceived self-efficacy, and/or difficulties in establishing an adaptive parent-infant relationship. Early developmental care interventions to support the parental role and infant development are essential and their impact can be assessed by an improvement of parental self-efficacy perception. The aims were to assess the effects of an early intervention provided in the NICU (the Joint Observation) on maternal perceived self-efficacy compared to controls (primary outcome) and to compare maternal mental health measures (perceived stress, anxiety, and depression), perception of the parent-infant relationship, and maternal responsiveness (secondary outcomes).

METHODS

This study was a monocentric randomized controlled trial registered in clinicatrials.gov (NCT02736136), which aimed at testing a behavioural intervention compared with treatment-as-usual. Mothers of preterm neonates born 28 to 32 6/7 weeks gestation were randomly allocated to either the intervention or the control groups. Outcome measures consisted of self-report questionnaires completed by the mothers at 1 and 6 months after enrollment and assessing perceived self-efficacy, mental health, perception of the parent-infant relationship and responsiveness, as well as satisfaction with the intervention.

RESULTS

No statistically significant group effects were observed for perceived maternal self-efficacy or the secondary outcomes. Over time, perceived maternal self-efficacy increased for mothers in both groups, while anxiety and depression symptoms decreased. High satisfaction with the intervention was reported.

CONCLUSIONS

The joint observation was not associated with improved perceived maternal self-efficacy or other mental health outcomes, but may constitute an additional supportive measure offered to parents in a vulnerable situation during the NICU stay.

[Repair effect of different doses of human umbilical cord mesenchymal stem cells on white matter injury in neonatal rats]

OBJECTIVES

To compare the repair effects of different doses of human umbilical cord mesenchymal stem cells (hUC-MSCs) on white matter injury (WMI) in neonatal rats.

METHODS

Two-day-old Sprague-Dawley neonatal rats were randomly divided into five groups: sham operation group, WMI group, and hUC-MSCs groups (low dose, medium dose, and high dose), with 24 rats in each group. Twenty-four hours after successful establishment of the neonatal rat white matter injury model, the WMI group was injected with sterile PBS via the lateral ventricle, while the hUC-MSCs groups received injections of hUC-MSCs at different doses. At 14 and 21 days post-modeling, hematoxylin and eosin staining was used to observe pathological changes in the tissues around the lateral ventricles. Real-time quantitative polymerase chain reaction was used to detect the quantitative expression of myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) mRNA in the brain tissue. Immunohistochemistry was employed to observe the expression levels of GFAP and neuron-specific nuclear protein (NeuN) in the tissues around the lateral ventricles. TUNEL staining was used to observe cell apoptosis in the tissues around the lateral ventricles. At 21 days post-modeling, the Morris water maze test was used to observe the spatial learning and memory capabilities of the neonatal rats.

RESULTS

At 14 and 21 days post-modeling, numerous cells with nuclear shrinkage and rupture, as well as disordered arrangement of nerve fibers, were observed in the tissues around the lateral ventricles of the WMI group and the low dose group. Compared with the WMI group, the medium and high dose groups showed alleviated pathological changes; the arrangement of nerve fibers in the medium dose group was relatively more orderly compared with the high dose group. Compared with the WMI group, there was no significant difference in the expression levels of MBP and GFAP mRNA in the low dose group (P>0.05), while the expression levels of MBP mRNA increased and GFAP mRNA decreased in the medium and high dose groups. The expression level of MBP mRNA in the medium dose group was higher than that in the high dose group, and the expression level of GFAP mRNA in the medium dose group was lower than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the protein expression of GFAP and NeuN in the low dose group (P>0.05), while the expression of NeuN protein increased and GFAP protein decreased in the medium and high dose groups. The expression of NeuN protein in the medium dose group was higher than that in the high dose group, and the expression of GFAP protein in the medium dose group was lower than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the number of apoptotic cells in the low dose group (P>0.05), while the number of apoptotic cells in the medium and high dose groups was less than that in the WMI group, and the number of apoptotic cells in the medium dose group was less than that in the high dose group (P<0.05). Compared with the WMI group, there was no significant difference in the escape latency time in the low dose group (P>0.05); starting from the third day of the latency period, the escape latency time in the medium dose group was less than that in the WMI group (P<0.05). The medium and high dose groups crossed the platform more times than the WMI group (P<0.05).

CONCLUSIONS

Low dose hUC-MSCs may yield unsatisfactory repair effects on WMI in neonatal rats, while medium and high doses of hUC-MSCs have significant repair effects, with the medium dose demonstrating superior efficacy.

Neuroprotective therapies in the NICU in preterm infants: present and future (Neonatal Neurocritical Care Series)

The survival of preterm infants has steadily improved thanks to advances in perinatal and neonatal intensive clinical care. The focus is now on finding ways to improve morbidities, especially neurological outcomes. Although antenatal steroids and magnesium for preterm infants have become routine therapies, studies have mainly demonstrated short-term benefits for antenatal steroid therapy but limited evidence for impact on long-term neurodevelopmental outcomes. Further advances in neuroprotective and neurorestorative therapies, improved neuromonitoring modalities to optimize recruitment in trials, and improved biomarkers to assess the response to treatment are essential. Among the most promising agents, multipotential stem cells, immunomodulation, and anti-inflammatory therapies can improve neural outcomes in preclinical studies and are the subject of considerable ongoing research. In the meantime, bundles of care protecting and nurturing the brain in the neonatal intensive care unit and beyond should be widely implemented in an effort to limit injury and promote neuroplasticity. IMPACT: With improved survival of preterm infants due to improved antenatal and neonatal care, our focus must now be to improve long-term neurological and neurodevelopmental outcomes. This review details the multifactorial pathogenesis of preterm brain injury and neuroprotective strategies in use at present, including antenatal care, seizure management and non-pharmacological NICU care. We discuss treatment strategies that are being evaluated as potential interventions to improve the neurodevelopmental outcomes of infants born prematurely.

All but Small: miRNAs from Wharton's Jelly-Mesenchymal Stromal Cell Small Extracellular Vesicles Rescue Premature White Matter Injury after Intranasal Administration

White matter injury (WMI) is a common neurological issue in premature-born neonates, often causing long-term disabilities. We recently demonstrated a key beneficial role of Wharton's jelly mesenchymal stromal cell-derived small extracellular vesicles (WJ-MSC-sEVs) microRNAs (miRNAs) in WMI-related processes in vitro. Here, we studied the functions of WJ-MSC-sEV miRNAs in vivo using a preclinical rat model of premature WMI. Premature WMI was induced in rat pups through inflammation and hypoxia-ischemia. Small EVs were purified from the culture supernatant of human WJ-MSCs. The capacity of WJ-MSC-sEV-derived miRNAs to decrease microglia activation and promote oligodendrocyte maturation was evaluated by knocking down (k.d) DROSHA in WJ-MSCs, releasing sEVs containing significantly less mature miRNAs. Wharton's jelly MSC-sEVs intranasally administrated 24 h upon injury reached the brain within 1 h, remained detectable for at least 24 h, significantly reduced microglial activation, and promoted oligodendrocyte maturation. The DROSHA k.d in WJ-MSCs lowered the therapeutic capabilities of sEVs in experimental premature WMI. Our results strongly indicate the relevance of miRNAs in the therapeutic abilities of WJ-MSC-sEVs in premature WMI in vivo, opening the path to clinical application.

Changes in circMyt1l/rno-let-7d-5p/brain-derived neurotrophic factor. A damaged periventricular white matter damage model in neonatal rats

OBJECTIVES

To investigate the function of circMyt1l/rno-let-7d-5p/BDNF in the white matter damage of premature rats.

METHODS

Bioinformatic analysis was used to analyze the differential expression of circMyt1l and its interacting miRNAs and mRNAs in rats with periventricular white matter damage. Rats at postnatal day 3 had their right common carotid artery permanently ligated, and were then exposed for 2 h to 6 % O2, or sham surgery and exposure to normal O2 levels (sham). CircMyt1l and rno-let-7d-5p expression was detected and BDNF protein levels were analyzed at 24, 48, and 72 h post hypoxia-ischemia.

RESULTS

Bioinformatic analysis suggested that circMyt1l, rno-let-7d-5p and BDNF interact. CircMyt1l expression decreased significantly relative to the sham-operated rats (p<0.01) in an exposure time-dependent manner. Contrastingly, rno-let-7d-5p increased significantly relative to the sham-operated rats (p<0.01) in an exposure time dependent manner. BDNF protein levels decreased significantly relative to the sham-operated rats (p<0.05) in an exposure time dependent manner.

CONCLUSIONS

The expression levels of circMyt1l/rno-let-7d-5p/BDNF are interrelated in periventricular white matter damage. Decreased circMyt1l expression of promoted the effect of rno-let-7d-5p and decreased the level of its target, BDNF.

Overexpression of miR-199a-5p improves brain injury in newborn rats with intrauterine infection via inhibition of astrocyte activation

White matter injury is the most common form of brain injury in preterm infants. In addition to hypoxia ischemia, intrauterine infection is most closely related to brain white matter injury. Our study aimed to explore the mechanism of the miR-199a-5p/HIF-1α axis on astrocyte activation and brain injury in newborn rats caused by intrauterine infection. The animal/cell model was established via escherichia coli infection/lipopolysaccharide induction, followed by the measurement of body weight, brain weight, and the pathological changes in brain tissues of newborn rats, and the pathological changes in placenta and uterus wall of pregnant rats. Also, the levels of GFAP, TNF-α, MDA, GSH, SOD, miR-199a-5p, and HIF-1α were detected though corresponding assays or kits. In vitro, cell viability and apoptosis and the levels of IL-6 and TNF-α were evaluated in astrocytes. Moreover, the targeting relationship between miR-199a-5p and HIF-1α was verified. miR-199a-5p was lowly expressed in the brain tissues of newborn rats with intrauterine infection. Overexpression of miR-199a-5p relieved the injury of placenta and uterus wall in pregnant rats and brain injury in newborn rats, accompanied by decreased HIF-1α, GFAP, TNF-α, and MDA levels and increased GSH and SOD levels. Results from cell models showed that miR-199a-5p overexpression inhibited astrocyte activation, shown by enhanced cell viability, weakened cell apoptosis, and decreased GFAP, IL-6, and TNF-α. Mechanistically, miR-199a-5p targeted HIF-1α to decrease its expression. Collectively, miR-199a-5p inhibited astrocyte activation and alleviated brain injury in newborn rats with intrauterine infection by reducing HIF-1α expression.

Associations of behavioral problems with white matter circuits connecting to the frontal lobes in school-aged children born at term and preterm

Introduction

This study investigated whether behavioral problems in children were associated with fractional anisotropy (FA) of white matter tracts connecting from other brain regions to right and left frontal lobes. We considered internalizing and externalizing behavioral problems separately and contrasted patterns of associations in children born at term and very preterm.

Methods

Parents completed the Child Behavior Checklist/6-18 questionnaire to quantify behavioral problems when their children were age 8 years (N=36 FT and 37 PT). Diffusion magnetic resonance scans were collected at the same age and analyzed using probabilistic tractography. We used multiple linear regression to investigate the strength of association between age-adjusted T-scores of internalizing and externalizing problems and mean fractional anisotropy (mean-FA) of right and left uncinate, arcuate, and anterior thalamic radiations, controlling for birth group and sex.

Results

Regression models predicting internalizing T-scores from mean-FA found significant group-by-tract interactions for the left and right arcuate and right uncinate. Internalizing scores were negatively associated with mean-FA of left and right arcuate only in children born at term (pleft AF =0.01, pright AF =0.01). Regression models predicting externalizing T-scores from mean-FA found significant group-by-tract interactions for the left arcuate and right uncinate. Externalizing scores were negatively associated with mean-FA of right uncinate in children born at term (pright UF =0.01) and positively associated in children born preterm (pright UF preterm =0.01). Other models were not significant.

Conclusions

In this sample of children with scores for behavioral problems across the full range, internalizing and externalizing behavioral problems were negatively associated with mean-FA of white matter tracts connecting to frontal lobes in children born at term; externalizing behavioral problems were positively associated with mean-FA of the right uncinate in children born preterm. The different associations by birth group suggest that the neurobiology of behavioral problems differs in the two birth groups.

The Impact of Intraventricular Hemorrhage and Periventricular Leukomalacia on Mortality and Neurodevelopmental Outcome in Very Preterm and Very Low Birthweight Infants: A Prospective Population-based Cohort Study

OBJECTIVE

To survey the incidence of intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL) by gestational age and to report the impact on mortality and neurodevelopmental outcome in very preterm/very low birthweight infants.

STUDY DESIGN

This was a population-based cohort study of 1927 very preterm/very low birthweight infants born in 2014-2016 and admitted to Flemish neonatal intensive care units. Infants underwent standard follow-up assessment until 2 years corrected age with the Bayley Scales of Infant and Toddler Development and neurological assessments.

RESULTS

No brain lesion was present in 31% of infants born at <26 weeks of gestation and 75.8% in infants born at 29-32 weeks of gestation. The prevalence of low-grade IVH/PVL (grades I and II) was 16.8% and 12.7%, respectively. Low-grade IVH/PVL was not related significantly to an increased likelihood of mortality, motor delay, or cognitive delay, except for PVL grade II, which was associated with a 4-fold increase in developing cerebral palsy (OR, 4.1; 95% CI, 1.2-14.6). High-grade lesions (III-IV) were present in 22.0% of the infants born at <26 weeks of gestational and 3.1% at 29-32 weeks of gestation, and the odds of death were ≥14.0 (IVH: OR, 14.0; 95% CI, 9.0-21.9; PVL: OR, 14.1; 95% CI, 6.6-29.9). PVL grades III-IV showed an increased odds of 17.2 for motor delay and 12.3 for cerebral palsy, but were not found to be associated significantly with cognitive delay (OR, 2.9; 95% CI, 0.5-17.5; P = .24).

CONCLUSIONS

Both the prevalence and severity of IVH/PVL decreased significantly with advancing gestational age. More than 75% of all infants with low grades of IVH/PVL showed normal motor and cognitive outcome at 2 years corrected age. High-grade PVL/IVH has become less common and is associated with adverse outcomes.

Quantitative ultrasonographic examination of cerebral white matter by pixel brightness intensity as marker of middle-term neurodevelopment: a prospective observational study

Non-cystic white matter (WM) injury has become prevalent among preterm newborns and is associated with long-term neurodevelopmental impairment. Magnetic resonance is the gold-standard for diagnosis; however, cranial ultrasound (CUS) is more easily available but limited by subjective interpretation of images. To overcome this problem, we enrolled in a prospective observational study, patients with gestational age at birth < 32 weeks with normal CUS scans or grade 1 WM injury. Patients underwent CUS examinations at 0-7 days of life (T0), 14-35 days of life (T1), 370/7-416/7 weeks' postmenstrual age (T2), and 420/7-520/7 weeks' postmenstrual age (T3). The echogenicity of parieto-occipital periventricular WM relative to that of homolateral choroid plexus (RECP) was calculated on parasagittal scans by means of pixel brightness intensity and its relationship with Bayley-III assessment at 12 months' corrected age was evaluated. We demonstrated that: (1) Left RECP values at T1 negatively correlated with cognitive composite scores; (2) Right RECP values at T2 and T3 negatively correlated with language composite scores; (3) Left RECP values at T1 and T2 negatively correlated with motor composite scores. Thus, this technique may be used as screening method to early identify patients at risk of neurodevelopmental issues and promptly initiate preventive and therapeutic interventions.

MicroRNA Cargo in Wharton's Jelly MSC Small Extracellular Vesicles: Key Functionality to In Vitro Prevention and Treatment of Premature White Matter Injury

Preterm birth is the leading cause of childhood morbidity and mortality and can result in white matter injury (WMI), leading to long-term neurological disabilities with global health burden. Mesenchymal stromal cell-derived small extracellular vesicles (MSC-sEV) are a promising therapeutic agent for treating perinatal neurological injury. They carry microRNAs (miRNAs) predicted to be involved in the onset of premature WMI. We hypothesize that miRNAs have a key function in the beneficial effects of MSC-sEV. We isolated MSC from umbilical cord tissue, the Wharton's jelly (WJ), and purified small extracellular vesicles (sEV) from WJ-MSC culture supernatant by ultracentrifugation and size exclusion chromatography. The miRNA content was quantified by real-time polymerase chain reaction. A luciferase gene assay validated silencing of TP53 and TAOK1, which we previously identified as predicted target genes of MSC-sEV miRNAs by Next Generation Sequencing and pathway enrichment analysis. The impact of sEV miRNAs on oligodendroglial maturation and neuronal apoptosis was evaluated using an in vitro oxygen-glucose deprivation model (OGD/R) by knocking-down DROSHA in WJ-MSC, which initiates miRNA processing. WJ-MSC-sEV contained miRNAs involved in WMI, namely hsa-miR-22-3p, hsa-miR-21-5p, hsa-miR-27b-3p, and the hsa-let-7 family. The luciferase assay strongly indicated an inhibitory effect of sEV miRNAs on the gene expression of TP53 and TAOK1. Small EV initiated oligodendrocyte maturation and reduced OGD/R-mediated neuronal apoptosis. Knocking-down DROSHA in WJ-MSC reduced the expression of sEV miRNAs and led to the loss of their beneficial effects. Our in vitro study strongly indicates the key function of miRNAs in the therapeutic potential of WJ-MSC-sEV in premature WMI.

Association of Cystic Periventricular Leukomalacia and Postnatal Epilepsy in Very Preterm Infants

INTRODUCTION

Cystic periventricular leukomalacia (PVL) is the most common white matter injury and a common cause of cerebral palsy in preterm infants. Postnatal epilepsy may occur after cystic PVL, but their causal relationship remains uncertain. Our aim was to validate the contribution of cystic PVL to postnatal epilepsy in very preterm infants and demonstrate their seizure characteristics.

METHODS

This prospective cohort study enrolled 1,342 preterm infants (birth weight <1,500 g and gestational age <32 weeks) from 2003 to 2015. Cystic PVL was diagnosed by serial cerebral ultrasound, and other comorbidities were recorded during hospitalization. Neurological developments and consequences, including epilepsy, were serially accessed until the age of 5.

RESULTS

A total of 976 preterm infants completed a 5-year neurological follow-up; 47 (4.8%) had cystic PVL. Preterm infants with cystic PVL were commonly associated with other comorbidities, including necrotizing enterocolitis stage III, neonatal seizures, and intraventricular hemorrhage during hospitalization. At age 5, 14 of the 47 (29.8%) preterm infants with cystic PVL had postnatal epilepsy. After adjusting for gender, gestational age, and three common comorbidities, cystic PVL was an independent risk factor for postnatal epilepsy (adjust OR: 16.2; 95% CI: 6.8-38.4; p < 0.001). Postnatal epilepsy after cystic PVL was commonly the generalized type (13 of 14, 92.9%), not intractable and most occurred after 1 year of age.

DISCUSSION/CONCLUSION

Cystic PVL would independently lead to postnatal epilepsy. Preterm infants with cystic PVL are at risk of postnatal epilepsy after age 1 in addition to cerebral palsy.

Pathogenesis from the microbial-gut-brain axis in white matter injury in preterm infants: A review

White matter injury (WMI) in premature infants is a unique form of brain injury and a common cause of chronic nervous system conditions such as cerebral palsy and neurobehavioral disorders. Very preterm infants who survive are at high risk of WMI. With developing research regarding the pathogenesis of premature WMI, the role of gut microbiota has attracted increasing attention in this field. As premature infants are a special group, early microbial colonization of the microbiome can affect brain development, and microbiome optimization can improve outcomes regarding nervous system development. As an important communication medium between the gut and the nervous system, intestinal microbes form a microbial-gut-brain axis. This axis affects the occurrence of WMI in premature infants via the metabolites produced by intestinal microorganisms, while also regulating cytokines and mediating oxidative stress. At the same time, deficiencies in the microbiota and their metabolites may exacerbate WMI in premature infants. This confers promise for probiotics and prebiotics as treatments for improving neurodevelopmental outcomes. Therefore, this review attempted to elucidate the potential mechanisms behind the communication of gut bacteria and the immature brain through the gut-brain axis, so as to provide a reference for further prevention and treatment of premature WMI.

Intellectual functioning in survivors of extremely low birthweight: Cognitive outcomes in childhood and adolescence

BACKGROUND

Infants born at extremely low birthweight (ELBW: ≤1000 g) are vulnerable to intellectual disabilities, but the factors that may distinguish between ELBW survivors with and without these impairments are not well understood. In this study, prospective associations between neonatal factors and functional outcomes in childhood and adolescence were compared in ELBW survivors with and without borderline intellectual functioning (BIF).

METHODS

Borderline intellectual functioning was defined by IQ < 85, assessed at 8 years. Among 146 ELBW survivors, 48 (33%) had IQ scores under 85, and 98 (67%) had scores equal to or over 85. Group differences in demographic and risk factors were assessed via t-test, chi-squared analysis or non-parametric tests. Neonatal factors that differed between ELBW groups were tested for association with adaptive behaviour assessed at age 5 years, and reading and arithmetic skills assessed at ages 8 and 15 years, using hierarchical regression models.

RESULTS

Extremely low birthweight survivors with BIF had significantly lower birthweights than ELBW survivors without BIF (790 vs. 855 g, P < 0.01) and were more likely to be born to mothers with lower socioeconomic status (SES) (78% vs. 48%, P < 0.01). These ELBW survivors also were more likely to be diagnosed with significant neurosensory impairment (NSI; 35% vs. 19%, P < 0.04), experienced more bronchopulmonary dysplasia (56% vs. 38%, P < 0.04), received more days of respiratory support (median 33 vs. 14 days, P < 0.01) and remained in hospital for longer periods (median 81 vs. 63 days, P < 0.03). Birthweight, familial SES, NSI and duration of respiratory support were significant predictors for one or more outcomes. Across groups, lower familial SES was associated with lower academic scores (Ps < 0.05), and NSI predicted lower adaptive functioning (Ps < 0.001). Other associations were moderated by group: among ELBW survivors with BIF, heavier birthweights predicted better arithmetic skills, the presence of NSI was associated with poorer arithmetic skills and more ventilation days predicted poorer reading skills.

CONCLUSIONS

At birth, ELBW survivors with BIF faced more physiological and social disadvantages and required more medical intervention than their ELBW peers without BIF. Smaller birth size, NSI burden and prolonged neonatal ventilatory support displayed gradients of risk for childhood and adolescent academic outcomes across groups. Whereas academic performance in ELBW survivors with BIF was sensitive to variation in birth size, NSI or ventilation days, ELBW survivors without BIF attained thresholds of intellectual ability that were sufficient to support higher levels of academic performance at both ages, regardless of their status on these factors. The findings are discussed in relation to Zigler's developmental theory of intellectual disability.

Risk Factors of Language Delay at Two Years of Corrected Age among Very-Low-Birth-Weight Preterm Infants: A Population-Based Study

Language delays are often underestimated in very-low-birth-weight (VLBW) preterm infants. We aimed to identify the risk factors of language delay at two years of corrected age in this vulnerable population. VLBW infants, who were assessed at two years of corrected age using the Bayley Scale of Infant Development, third edition, were included using a population-based cohort database. Language delay was defined as mild to moderate if the composite score was between 70 and 85 and severe if the score was < 70. Multivariable logistic regression analysis was used to identify the perinatal risk factors associated with language delay. The study comprised 3797 VLBW preterm infants; 678 (18%) had a mild to moderate delay and 235 (6%) had a severe delay. After adjusting for confounding factors, low maternal education level, low maternal socioeconomic status, extremely low birth weight, male sex, and severe intraventricular hemorrhage (IVH) and/or cystic periventricular leukomalacia (PVL) were found to be significantly associated with both mild to moderate and severe delays. Resuscitation at delivery, necrotizing enterocolitis, and patent ductus arteriosus requiring ligation showed significant associations with severe delay. The strongest factors predicting both mild to moderate and severe language delays were the male sex and severe IVH and/or cystic PVL; thus, early targeted intervention is warranted in these populations.

Ultrasonographic evaluation of the early brain growth pattern in very low birth weight infants

BACKGROUND

Preterm infants develop smaller brain volumes compared to term newborns. Our aim is to study early brain growth related to perinatal factors in very low birth weight infants (VLBWI).

METHODS

Manual segmentation of total brain volume (TBV) was performed in weekly 3D-ultrasonographies in our cohort of VLBWI. We studied the brain growth pattern related to term magnetic resonance image (term-MRI).

RESULTS

We found different brain growth trajectories, with smaller brain volumes and a decrease in brain growth rate in those VLBWI who would later have an abnormal term-MRI (mean TBV 190.68 vs. 213.9 cm3; P = 0.0001 and mean TBV growth rate 14.35 (±1.27) vs. 16.94 (±2.29) cm3/week; P = 0.0001). TBV in those with normal term-MRI was related to gestational age (GA), being small for gestational age (SGA), sex, and duration of parenteral nutrition (TPN) while in those with abnormal term-MRI findings it was related to GA, SGA, TPN, and comorbidities. We found a deceleration in brain growth rate in those with ≥3 comorbidities.

CONCLUSIONS

An altered brain growth pattern in VLBWI who subsequently present worst scores on term-MRI is related to GA, being SGA and comorbidities. Early ultrasonographic monitoring of TBV could be useful to detect deviated patterns of brain growth.

IMPACT STATEMENT

We describe the brain growth pattern in very low birth weight infants during their first postnatal weeks. Brain growth may be affected in the presence of certain perinatal factors and comorbidities, conditioning a deviation of the normal growth pattern. The serial ultrasound follow-up of these at-risk patients allows identifying these brain growth patterns early, which offers a window of opportunity for implementing earlier interventions.

The association of γδT lymphocytes with cystic leukomalacia in premature infants

Background

Periventricular leukomalacia (PVL) is an essential cause of cerebral palsy in preterm infants, and cystic PVL (cPVL) is the most severe form of the disease. The pathogenesis of cPVL is complex, and immune imbalances and inflammatory responses may play an essential role in it.

Objective

This study aimed to investigate the correlation between peripheral blood lymphocyte subsets, especially γδT cells with the pathogenesis of cPVL in preterm infants.

Methods

Peripheral blood from preterm infants with GA < 32 weeks and BW < 1,500 g was used in this study and was collected at 34 weeks corrected gestational age and within 24 h after the diagnosis with cranial MRI or cranial ultrasound. The infants were divided into cPVL groups and control groups. Flow cytometry was used to detect peripheral blood γδT, CD3+, CD4+, CD8+, and the proportion of total lymphocytes. Multiplex cell assays were used to detect the concentration of extracellular serum cytokines IL-6, IL-2, IL-8, IL-17A, IL-10, IL-1RA, eotaxin (CCL11), MCP-1 (CCL2), CXCL1, G-CSF, and IFNγ. A follow-up visit was carried out when the patient was 3 years old.

Results

After correcting for confounding factors, the proportion of peripheral blood γδT in the cPVL group was significantly lower than that in the control group (β: 0.216; 95% CI: 0.058-0.800, P < 0.022). Peripheral blood γδT (AUC: 0.722, P=0.006) and multivariate binary regression model (AUC: 0.865, P < 0.000) have good diagnostic values for cPVL. Peripheral blood γδT has some predictive power for neurodevelopmental outcomes in preterm infants (AUC: 0.743, P = 0.002).

Conclusion

It seems that peripheral blood γδT cells are inversely correlated with cPVL, which is not only a risk factor for cPVL disease but also neurodevelopmental outcomes in preterm infants. However, the causality of cPVL and various lymphocytes is unclear and needs further study.

Brain Development and Maternal Behavior in Relation to Cognitive and Language Outcomes in Preterm-Born Children

BACKGROUND

Children born very preterm (≤32 weeks gestational age) show poorer cognitive and language development compared with their term-born peers. The importance of supportive maternal responses to the child's cues for promoting neurodevelopment is well established. However, little is known about whether supportive maternal behavior can buffer the association of early brain dysmaturation with cognitive and language performance.

METHODS

Infants born very preterm (N = 226) were recruited from the neonatal intensive care unit for a prospective, observational cohort study. Chart review (e.g., size at birth, postnatal infection) was conducted from birth to discharge. Magnetic resonance imaging, including diffusion tensor imaging, was acquired at approximately 32 weeks postmenstrual age and again at term-equivalent age. Fractional anisotropy, a quantitative measure of brain maturation, was obtained from 11 bilateral regions of interest in the cortical gray matter. At 3 years (n = 187), neurodevelopmental testing (Bayley Scales of Infant and Toddler Development-III) was administered, and parent-child interaction was filmed. Maternal behavior was scored using the Emotional Availability Scale-IV. A total of 146 infants with neonatal brain imaging and follow-up data were included for analysis. Generalized estimating equations were used to examine whether maternal support interacted with mean fractional anisotropy values to predict Cognitive and Language scores at 3 years, accounting for confounding neonatal and maternal factors.

RESULTS

Higher maternal support significantly moderated cortical fractional anisotropy values at term-equivalent age to predict higher Cognitive (interaction term β = 2.01, p = .05) and Language (interaction term β = 1.85, p = .04) scores.

CONCLUSIONS

Findings suggest that supportive maternal behavior following early brain dysmaturation may provide an opportunity to promote optimal neurodevelopment in children born very preterm.

MicroRNA-21-5p agomir inhibits apoptosis of oligodendrocyte precursor cell and attenuates white matter injury in neonatal rats

BACKGROUND AND RESEARCH QUESTION/HYPOTHESIS

Excessive oligodendrocyte precursor cell (OPC) apoptosis occurs during intrauterine infection-induced white matter injury (WMI) in premature infants, preventing excessive apoptosis of OPCs is one of the mechanisms protecting WMI. Micro-RNA-21-5p (miR-21-5p) mediating anti-apoptotic activity was observed in other diseases. Therefore, the aim of this study was to determine whether miR-21-5p protects against WMI by modulating phosphatase and tensin homolog deleted on chromosome 10/phosphatidylinositol-3-kinase/protein kinase B (PTEN/PI3K/Akt) signaling pathway.

METHODS

A lipopolysaccharide (LPS)-induced neonatal Sprague-Dawley (SD) rat model of preterm WMI was established. To explore the effect of miR-21-5p on WMI, we intraventricularly injected miR-21-5p agomir and miR-21-5p antagomir to activate or inhibit endogenous miR-21-5p. Immunofluorescent labelling of myelin basic protein, immunohistochemical labelling of 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase), and terminal deoxynucleotidyl transferase dUTP nick end labelling assays were conducted to observe pathological white matter changes. The antibody of anti-oligodendrocyte marker 4 (O4) was used to specifically recognise OPCs. The expressions of miR-21-5p and PTEN mRNA in the brain were detected with quantitative real-time polymerase chain reaction (qRT-PCR). PTEN, Akt, and phosphorylated Akt (p-Akt) protein levels were assayed with western blotting, and apoptotic proteins associated with PI3K/Akt signalling were quantified.

RESULTS

Intense white matter dysplasia and excessive OPC apoptosis were observed in the brains of rats with WMI. When the miR-21-5p agonist miR-21-5p agomir was used in the WMI group, apoptosis of OPCs was significantly reduced, and myelin maturation increased. MiR-21-5p agomir relieved WMI. MiR-21-5p agomir inhibited the mRNA and protein expression of PTEN, increased p-Akt phosphorylation, and decreased the expression and activation of related apoptotic proteins.On the other hand, the administration of miR-21-5p specific blocker, miR-21-5p antagomir, reduced the level of p-AKT, increased OPC apoptosis, and worsened WMI.

INTERPRETATION

Our findings revealed that miR-21-5p agomir had anti-OPC over-apoptotic effects and enhanced myelin development in WMI by modulating the PTEN/Akt signaling pathway.

DATA AVAILABILITY STATEMENT

The datasets used and or/analysed in the current study are available from the corresponding author on reasonable request.

A translational mouse model for investigation of the mechanism of preterm diffuse white matter injury

BACKGROUND

The increasing incidence of preterm birth has led to a global problem of adverse neurodevelopmental outcomes in preterm neonates as a result of brain injury. There is still a lack of models mimicking diffuse white matter injury (WMI) in preterm neonates that can be applied to transgenic mice.

METHODS

The right common carotid artery of the neonatal mouse was ligated on postnatal day 3 (P3) C57BL/6 mice and followed by 80, 90, or 100 min of hypoxia using a mixture of 10%±0.2% oxygen-nitrogen. The most suitable model was chosen by characterizing the effects of this hypoxic-ischemic insult on development of myelin, glial cell conditions, and neurological outcomes by hematoxylin-eosin (HE) staining performed at postnatal day 17 (P17), western blot measuring myelin basic protein (MBP) at postnatal day 10 (P10) and P17, immunofluorescence staining of MBP-neurofilament protein heavy chain (NFH), oligodendrocyte transcription factor-2 (Olig2)-adenomatous polyposis coli clone (CC1), glial fibrillary acidic protein (GFAP) and ionic calcium linker protein (Iba-1) at P17, electron microscopy observing myelin microstructure at postnatal day 52 (P52) and behavioral testing at postnatal day 45-50 (P45-P50).

RESULTS

The 90-min group showed neuroanatomical changes in the ipsilateral side of the brain, the 80-min group showed minor changes, and the 100-min group showed severe injury. Mice in the 90-min group subsequently showed marked activation of astrocytes, augmentation of microglia, a notable decrease in expression of MBP with a normal level of NFH, long-term cognitive dysfunction, and impairment of the myelin ultrastructure in adulthood.

CONCLUSIONS

In conclusion, a mouse model of preterm diffuse WMI rather than cystic periventricular leukomalacia was successfully achieved by ligating one of the common carotid arteries on P3 followed by 90 min of hypoxia in a mixture of 10%±0.2% oxygen-nitrogen. The attempt provides an adequate translational animal model for elucidating the underlying mechanism.

Neuroscience meets nurture: challenges of prematurity and the critical role of family-centred and developmental care as a key part of the neuroprotection care bundle

Advances in neonatal-perinatal medicine have resulted in increased survival at lower gestations. Although the incidence of germinal matrix haemorrhage-intraventricular haemorrhage and cystic periventricular leucomalacia is reducing, a new phenotype of preterm brain injury has emerged consisting of a combination of destructive and dysmaturational effects. Consequently, severe neurological disability is reported at a lower rate than previously, but the overall morbidity associated with premature birth continues to present a large global burden and contributes significantly to increased financial costs to health systems and families. In this review, we examine the developmental milestones of fetal brain development and how preterm birth can disrupt this trajectory. We review common morbidities associated with premature birth today. Although drug-based and cell-based neuroprotective therapies for the preterm brain are under intense study, we outline basic, sustainable and effective non-medical, family-centred and developmental care strategies which have the potential to improve neurodevelopmental outcomes for this population and need to be considered part of the future neuroprotection care bundle.

White Matter Injury in Preterm Infants: Pathogenesis and Potential Therapy From the Aspect of the Gut–Brain Axis

Very preterm infants who survive are at high risk of white matter injury (WMI). With a greater understanding of the pathogenesis of WMI, the gut microbiota has recently drawn increasing attention in this field. This review tries to clarify the possible mechanisms behind the communication of the gut bacteria and the immature brain via the gut–brain axis. The gut microbiota releases signals, such as microbial metabolites. These metabolites regulate inflammatory and immune responses characterized by microglial activation, which ultimately impact the differentiation of pre-myelinating oligodendrocytes (pre-OLs) and lead to WMI. Moreover, probiotics and prebiotics emerge as a promising therapy to improve the neurodevelopmental outcome. However, future studies are required to clarify the function of these above products and the optimal time for their administration within a larger population. Based on the existing evidence, it is still too early to recommend probiotics and prebiotics as effective treatments for WMI.

Cerebral Venous Sinus Thrombosis in Preterm Infants

BACKGROUND:

Neonatal cerebral venous sinus thrombosis (CVST) can lead to brain injury and neurodevelopmental impairments. Previous studies of neonatal CVST have focused on term infants, and studies of preterm infants are lacking. In this study, we examined the clinical and radiological features, treatment and outcome of CVST in preterm infants.

METHODS:

This was a retrospective, consecutive cohort study of preterm infants (gestational age <37 weeks) with radiologically confirmed CVST. All magnetic resonance imaging/MRV and CT/CTV scans were re-reviewed to study thrombus characteristics and pattern of brain injury. Outcome was assessed by the validated pediatric stroke outcome measure at the most recent clinic visit.

RESULTS:

Twenty-six preterm infants with CVST were studied. Of these, 65% were moderate-late preterm (32–37 weeks), 27% very preterm (28–32 weeks), and 8% extreme preterm (<28 weeks). Most (73%) were symptomatic at presentation with seizures or abnormal exam. Transverse (85%) and superior sagittal (42%) sinuses were common sites of thrombosis. Parenchymal brain injury was predominantly periventricular (35%) and deep white matter (31%) in location. Intraventricular hemorrhage occurred in 46%. Most infants (69%) were treated with anticoagulation. No treated infant (including eleven with pretreatment hemorrhage) had new or worsening post-treatment hemorrhage. Outcomes ranged from no deficits (50%), mild-moderate (25%), and severe (25%) impairment.

CONCLUSIONS:

In our sample of preterm infants with CVST, more than one-quarter were asymptomatic. White matter brain lesions predominated and one-half had neurological deficits at follow-up. Anticoagulation of preterm CVST in this small cohort appeared to be safe. Larger studies of preterm CVST are needed.

PSB0788 ameliorates maternal inflammation-induced periventricular leukomalacia-like injury

Studies have shown that periventricular leukomalacia (PVL) is a distinctive form of cerebral white matter injury that pertains to myelination disturbances. Maternal inflammation is a main cause of white matter injury. Intrauterine inflammation cellular will be propagated to the developing brain by the entire maternal-placental-fetal axis, and triggers neural immune injury. As a low-affinity receptor, adenosine A_2B receptor (A_2BAR) requires high concentrations of adenosine to be significantly activated in pathological conditions. We hypothesized that in the maternal inflammation-induced PVL model, a selective A_2BAR antagonist PSB0788 had the potential to prevent the injury. In this work, a total of 18 SD pregnant rats were divided into three groups, and treated with intraperitoneal injection of phosphate buffered saline (PBS), lipopolysaccharide (LPS), or LPS+PSB0788. Placental infection was determined by H&E staining and the inflammatory condition was determined by ELISA. Change of MBP, NG2 and CC-1 in the brain of the rats' offspring were detected by western blot and immunohistochemistry. Furthermore, LPS-induced maternal inflammation reduced the expression of MBP, which related to the decrease in the numbers of OPCs and mature oligodendrocytes in neonate rats. After treatment with PSB0788, the levels of MBP proteins increased in the rats' offspring, improved the remyelination. In conclusion, our study shows that the selective A_2BAR antagonist PSB0788 plays an important role in promoting the normal development of OPCs in vivo by the maternal inflammation-induced PVL model. Future studies will focus on the mechanism of PSB0788 in this model.

Inhibiting miR-466b-5p Attenuates Neonatal White Matter Injury by Targeting Lpar1

miR-466b-5p is aberrantly upregulated in oligodendrocyte precursor cells (OPCs) after white matter injury (WMI). However, its roles in neonatal WMI pathogenesis are unknown. In this study, P3 rats were subjected to hypoxia-ischemia to establish a neonatal WMI model. A bioinformatic analysis was conducted to predict the possible target of miR-466b-5p as Lpar1. RT-PCR was performed to validate the expression of miR-466b-5p and Lpar1 mRNA. The miR-466b-5p antagomir was intracerebroventricularly administrated to inhibit miR-466b-5p; OPC differentiation, apoptosis, proliferation, and myelination were analyzed using immunofluorescence staining, western blotting, and electron microscopy. In addition, the behavioral performance of the rats was measured with the Morris water maze test. Sox10 expression and PLP trafficking were examined to elucidate the mechanism by which miR-466b-5p regulates WMI pathogenesis. We found that after inhibiting miR-466b-5p, the Edg2 protein was increased, OPC differentiation and myelinated axon formation were enhanced, and the rats' behavioral performance was improved, whereas OPC proliferation and apoptosis were not affected. Furthermore, the expression of Sox10 was promoted while PLP trafficking was attenuated after miR-466b-5p inhibition. We conclude that miR-466b-5p is involved in the regulation of WMI pathogenesis, partly through the Lpar1/Edg2/Sox10 and Lpar1/Edg2/PLP signaling pathways.

Biomarkers of Brain Injury: A Window on Mechanisms of Injury and Recovery in the Brain

The decision-making process regarding management after severe acute brain injury is based on clinical evaluation and depends on the injury etiology as well as radiological and neurophysiological data [...]

Gardenia jasminoides J. Ellis extract alleviated white matter damage through promoting the differentiation of oligodendrocyte precursor cells via suppressing neuroinflammation

Increasing evidence has highlighted the role of white matter damage in the pathology of Alzheimer's disease (AD). Previous research has shown that a mixture of crocin analogues (GJ-4), Gardenia jasminoides J. Ellis extract, improved cognition in several AD mouse models, but the mechanism remains unclear. The aim of the present study was to investigate the effects and underlying mechanisms of GJ-4 on white matter damage. Proteomic analysis and western blotting results suggested that the level of myelin-related proteins, including myelin basic protein (MBP), myelin associated glycoprotein (MAG) and myelin associated oligodendrocyte basic protein (MOBP), was significantly decreased in the brain of PrP-hAβPPswe/PS1ΔE9 (APP/PS1) transgenic mice, and GJ-4 treatment increased the expressions of these proteins. This result revealed that GJ-4 could ameliorate myelin injury, suggesting that this might be a possible mechanism of GJ-4 on cognition. To validate the effects of GJ-4 on myelin, a metabolite of GJ-4, crocetin, which can pass through the blood-brain barrier, was applied in in vitro experiments. A mechanistic study revealed that crocetin significantly promoted the differentiation of primary cultured oligodendrocyte precursor cells to oligodendrocytes through up-regulation of nuclear Ki67 and transcription factor 2 (Olig2). Oligodendrocytes, the myelin-forming cells, have been reported to be lifelong partners of neurons. Therefore, to investigate the effects of crocetin on myelin and neurons, lysophosphatidylcholine (LPC)-treated primary mixed midbrain neuronal/glial culture was used. Immunofluorescence results indicated that crocetin treatment protected neurons and suppressed microglial activation against LPC-induced injury. To further discern the effects of GJ-4 on white matter injury and neuroinflammation, an LPC-induced mouse model was developed. GJ-4 administration increased oligodendrocyte proliferation, differentiation, and myelin repair. The mechanistic study indicated that GJ-4 improved white matter injury through the regulation of neuroinflammatory dysfunction. These data indicated that GJ-4 effectively repaired white matter damage in the LPC-treated mice. Thus, the present study supported GJ-4 as a potential therapeutic agent for AD and white matter related diseases.

Neonatal sepsis is associated with behavioral abnormalities in very low birthweight infants at preschool age

OBJECTIVE

This study aimed to investigate neonatal sepsis as potential risk factor for adverse behavioral outcome in very low birth weight infants (VLBWI) at preschool age. Regardless of improvements in the obstetric and neonatal intensive care, preterm infants are still at high risk for behavioral problems later in life. The spectrum, origin and potential risk factors of these behavioral problems have not been well-defined.

METHODS

In this retrospective observational study, the influence of culture-proven neonatal sepsis on the behavioral outcome of VLBWI born at a gestational age <32 weeks was analyzed at 5 years of age in a multivariable regression model. Behavior was assessed with the Child Behavior Checklist (CBCL). Neonatal morbidities, socioeconomic status and neurodevelopmental outcome served as covariates in the analysis.

RESULTS

312 VLBWI entered the final analysis, of whom 11% had experienced neonatal sepsis. Neonatal sepsis appeared to be a relevant risk factor for both internalizing, i.e., emotional reactivity and anxiety/depression, as well as externalizing behavioral problems, i.e., oppositional and aggressive behavior in this cohort of VLBWI. Low socioeconomic status and male gender were additional statistically significant risk factors for both internalizing and externalizing behavioral problems. No difference in neurocognitive development was observed between the groups.

CONCLUSION

The study supports the fact that VLBWI are vulnerable to multiple behavioral disorders independent of their cognitive development. In contrast to former assumptions, the results of the study emphasize that not only post-natal environment but also neonatal morbidities, especially neonatal sepsis, have an impact on behavioral outcome of VLBWI at preschool age.

Mothers with hypertensive disorders of pregnancy increased risk of periventricular leukomalacia in extremely preterm or extremely low birth weight infants: A propensity score analysis

BACKGROUND

At present, the conclusions about the impact of hypertensive disorders of pregnancy (HDP) on the clinical outcomes of preterm infants are inconsistent. This study used the propensity score matching (PSM) analysis to evaluate the effect of HDP on clinical outcomes of extremely preterm or extremely low birth weight (EP/ELBW) infants.

METHODS

Retrospective analysis was performed on the EP/ELBW infants discharged from 26 tertiary neonatal intensive care units or died during hospitalization from 2008 to 2017, who were divided into HDP group and non-HDP group. The six covariates including sex, gestational age, birth weight, twin or multiple pregnancy, antenatal steroids administration, and conception method were matched through the PSM method at a ratio of 1:1. The survival rate at discharge and the major clinical complications were compared between the two groups.

RESULTS

After matching the six covariates, compared with the non-HDP group, there was no significant difference in the survival rate at discharge (64 vs. 63.2%, p > 0.05), the incidence of bronchopulmonary dysplasia (BPD) or moderate to severe BPD in the HDP group (58.3 vs. 54.9%, p > 0.05; 5.2 vs. 6.2%, p > 0.05). The incidence of periventricular leukomalacia (PVL) in the HDP group was significantly increased (5.7 vs. 1.9%, p < 0.05).

CONCLUSIONS

HDP increased the risk of PVL in EP/ELBW infants, but had no significant effect on the survival rate at discharge, or the occurrence of other complications.

Decreased Fetal Movements: A Sign of Placental SARS-CoV-2 Infection with Perinatal Brain Injury

Neonatal COVID-19 is rare and mainly results from postnatal transmission. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), however, can infect the placenta and compromise its function. We present two cases of decreased fetal movements and abnormal fetal heart rhythm 5 days after mild maternal COVID-19, requiring emergency caesarean section at 29 + 3 and 32 + 1 weeks of gestation, and leading to brain injury. Placental examination revealed extensive and multifocal chronic intervillositis, with intense cytoplasmic positivity for SARS-CoV-2 spike antibody and SARS-CoV-2 detection by RT-qPCR. Vertical transmission was confirmed in one case, and both neonates developed extensive cystic peri-ventricular leukomalacia.

Exploring the distribution of grey and white matter brain volumes in extremely preterm children, using magnetic resonance imaging at term age and at 10 years of age

OBJECTIVES

To investigate differences in brain volumes between children born extremely preterm and term born controls at term age and at 10 years of age.

STUDY DESIGN

Children born extremely preterm (EPT), up to 26 weeks and 6 days gestational age, in Stockholm between January 1 2004 to March 31 2007 were included in this population-based cohort study. A total of 45 EPT infants were included at term age and 51 EPT children were included at 10 years of age. There were 27 EPT children included at both time points. Two different control groups were recruited; 15 control infants were included at term age and 38 control children at 10 years of age. The primary outcomes were the grey and white matter volumes. Linear regression, adjusted for intracranial volume and sex, was used.

RESULTS

At term age, the extremely preterm infants had significantly smaller grey matter volume compared to the control infants with an adjusted mean difference of 5.0 cm3 and a 95% confidence interval of -8.4 to -1.5 (p = 0.004). At 10 years of age the extremely preterm children had significantly smaller white matter volume compared to the control children with an adjusted mean difference of 6.0 cm3 and a 95% confidence interval of -10.9 to -1.0 (p = 0.010).

CONCLUSION

Extremely preterm birth was associated with reduced grey matter volume at term age and reduced white matter volume at 10 years of age compared to term born controls.

The dimensions of white matter injury in preterm neonates

White matter injury (WMI) represents a frequent form of parenchymal brain injury in preterm neonates. Several dimensions of WMI are recognized, with distinct neuropathologic features involving a combination of destructive and maturational anomalies. Hypoxia-ischemia is the main mechanism leading to WMI and adverse white matter development, which result from injury to the oligodendrocyte precursor cells. Inflammation might act as a potentiator for WMI. A combination of hypoxia-ischemia and inflammation is frequent in several neonatal comorbidities such as postnatal infections, NEC and bronchopulmonary dysplasia, all known contributors to WMI. White matter injury is an important predictor of adverse neurodevelopmental outcomes. When WMI is detected on neonatal brain imaging, a detailed characterization of the injury (pattern of injury, severity and location) may enhance the ability to predict outcomes. This clinically-oriented review will provide an overview of the pathophysiology and imaging diagnosis of the multiple dimensions of WMI, will explore the association between postnatal complications and WMI, and will provide guidance on the signification of white matter anomalies for motor and cognitive development.

The Role of Extracellular Vesicles in the Developing Brain: Current Perspective and Promising Source of Biomarkers and Therapy for Perinatal Brain Injury

This comprehensive review focuses on our current understanding of the proposed physiological and pathological functions of extracellular vesicles (EVs) in the developing brain. Furthermore, since EVs have attracted great interest as potential novel cell-free therapeutics, we discuss advances in the knowledge of stem cell- and astrocyte-derived EVs in relation to their potential for protection and repair following perinatal brain injury. This review identified 13 peer-reviewed studies evaluating the efficacy of EVs in animal models of perinatal brain injury; 12/13 utilized mesenchymal stem cell-derived EVs (MSC-EVs) and 1/13 utilized astrocyte-derived EVs. Animal model, method of EV isolation and size, route, timing, and dose administered varied between studies. Notwithstanding, EV treatment either improved and/or preserved perinatal brain structures both macroscopically and microscopically. Additionally, EV treatment modulated inflammatory responses and improved brain function. Collectively this suggests EVs can ameliorate, or repair damage associated with perinatal brain injury. These findings warrant further investigation to identify the optimal cell numbers, source, and dosage regimens of EVs, including long-term effects on functional outcomes.

Cumulative Damage: Cell Death in Posthemorrhagic Hydrocephalus of Prematurity

Globally, approximately 11% of all infants are born preterm, prior to 37 weeks’ gestation. In these high-risk neonates, encephalopathy of prematurity (EoP) is a major cause of both morbidity and mortality, especially for neonates who are born very preterm (<32 weeks gestation). EoP encompasses numerous types of preterm birth-related brain abnormalities and injuries, and can culminate in a diverse array of neurodevelopmental impairments. Of note, posthemorrhagic hydrocephalus of prematurity (PHHP) can be conceptualized as a severe manifestation of EoP. PHHP impacts the immature neonatal brain at a crucial timepoint during neurodevelopment, and can result in permanent, detrimental consequences to not only cerebrospinal fluid (CSF) dynamics, but also to white and gray matter development. In this review, the relevant literature related to the diverse mechanisms of cell death in the setting of PHHP will be thoroughly discussed. Loss of the epithelial cells of the choroid plexus, ependymal cells and their motile cilia, and cellular structures within the glymphatic system are of particular interest. Greater insights into the injuries, initiating targets, and downstream signaling pathways involved in excess cell death shed light on promising areas for therapeutic intervention. This will bolster current efforts to prevent, mitigate, and reverse the consequential brain remodeling that occurs as a result of hydrocephalus and other components of EoP.

[Role and mechanism of circular RNA in brain injury induced by inflammation in preterm mice: a preliminary study]

OBJECTIVE

To determine the association of circular RNA (circRNA) and circRNA-microRNA (miRNA) network regulation with brain injury induced by inflammation in preterm mice.

METHODS

Pregnant mice were treated with intraperitoneally injected lipopolysaccharide to establish a preterm mouse model of brain injury induced by inflammation (inflammation preterm group with 3 mice). Preterm mice born to normal pregnant mice by cesarean section were selected as controls (non-inflammation preterm group with 3 mice). The gene microarray technique was used to screen out the circRNAs associated with brain injury in preterm mice. The miRNA target prediction software was used to predict the binding sites between circRNAs and miRNAs and analyze the regulatory mechanism.

RESULTS

A total of 365 differentially expressed circRNAs were screened out between the inflammation preterm and non-inflammation preterm groups (fold change > 1.5, P < 0.05), among which there were 206 upregulated circRNAs and 159 downregulated circRNAs. Further analysis of the circRNAs with a fold change of > 4 showed that these circRNAs could bind to miRNAs and regulate their activity, thereby regulating the expression of the genes associated with the nervous system.

CONCLUSIONS

Inflammation induces a significant change in the expression profile of circRNAs in the brain tissue of mice, and the change in the expression of circRNAs plays an important role in brain injury induced by inflammation and subsequent brain development in preterm mice.

Social cognition in individuals born preterm

Faces hold a substantial value for effective social interactions and sharing. Covering faces with masks, due to COVID-19 regulations, may lead to difficulties in using social signals, in particular, in individuals with neurodevelopmental conditions. Daily-life social participation of individuals who were born preterm is of immense importance for their quality of life. Here we examined face tuning in individuals (aged 12.79 ± 1.89 years) who were born preterm and exhibited signs of periventricular leukomalacia (PVL), a dominant form of brain injury in preterm birth survivors. For assessing the face sensitivity in this population, we implemented a recently developed experimental tool, a set of Face-n-Food images bordering on the style of Giuseppe Arcimboldo. The key benefit of these images is that single components do not trigger face processing. Although a coarse face schema is thought to be hardwired in the brain, former preterms exhibit substantial shortages in the face tuning not only compared with typically developing controls but also with individuals with autistic spectrum disorders. The lack of correlations between the face sensitivity and other cognitive abilities indicates that these deficits are domain-specific. This underscores impact of preterm birth sequelae for social functioning at large. Comparison of the findings with data in individuals with other neurodevelopmental and neuropsychiatric conditions provides novel insights into the origins of deficient face processing.

Dystonia assessment in children with cerebral palsy and periventricular leukomalacia

OBJECTIVE

To describe the frequency, motor phenotype, clinical patterns and functional consequences of dystonia in patients with cerebral palsy (CP) in the setting of periventricular leukomalacia.

METHODS

Retrospective analysis of a cohort of 31 patients with CP and periventricular leukomalacia. Gross Motor Function Classification System (GMFCS) and Manual Ability Classification System (MACS) were used to classify functional ability. Spasticity was rated using the Modified Ashworth Scale. Presence of dystonia was assessed by reviewing video recordings, and its severity by using the Burke-Fahn-Marsden Dystonia Rating Scale.

RESULTS

All patients showed evidence of dystonia involving upper and/or lower limbs, neck, trunk, mouth and eyes in order of frequency. In 29% of patients dystonia involved only the limbs and in 71% it was multifocal. Dystonia severity ranged from slight to severe. Severity and distribution of dystonia did not correlate with gender, age, weeks of gestation or duration of neonatal unit stay. GMFCS and MACS correlated with dystonia but not with spasticity.

CONCLUSIONS

Severity of dystonia, but not spasticity is associated with the severity of motor functional disability in CP patients with periventricular leukomalacia and demonstrates the key role of dystonia in the motor function of these patients.

Phasic and tonic alertness in preterm 5-year-old healthy children

Preterm delivery may interrupt the intrauterine brain development and implies a risk factor for the developing brain. In the long term, most frequently particular forms of attention deficits are described which refer to the basic aspects of attention i.e., arousal or tonic alertness. As this reflects top-down processes, the current study focuses on bottom-up processed phasic alertness in preschool aged preterm children. Additionally, we made a division of response times into decision and movement time to quantify more exactly the contribution of cognitive and motor performance to reaction times. We investigated basic aspects of attention functioning and contrasted phasic and tonic alertness in 31 low-risk healthy preterm (28-36 weeks of gestation) and 22 term children of five to 6 years of age by using a self-designed computerized test. Preterm children exhibited delayed decision and reaction time in the tonic non-cued alertness condition but not in the phasic cued alertness condition compared to term children. Current results suggest that preterm birth, even when clinically relevant symptoms are absent, may have long-term consequences on basic aspects of attention functioning. Results further suggest that preterm children may profit from auditory cues to overcome these deviations, which yield evidence for a clear distinction between impaired top-down and intact bottom-up controlled processes. These findings might provide a promising groundwork for the development of therapeutical interventions and prevention strategies, whose use and impact to support preterm children should be addressed in further investigations.

Tertiary cystic white matter injury as a potential phenomenon after hypoxia-ischaemia in preterm f sheep

White matter injury, including both diffuse and cystic elements, remains highly associated with neurodevelopmental disability and cerebral palsy in preterm infants, yet its pathogenesis and evolution are still poorly understood and there is no established treatment. We examined the long-term evolution of white matter injury in chronically instrumented preterm fetal sheep (0.7 gestation) after 25 min of complete umbilical cord occlusion or sham occlusion. Fetal brains were processed for histology after 3 days (n = 9, sham n = 9), 7 days (n = 8, sham n = 8), 14 days (n = 9, sham n = 8) and 21 days (n = 9, sham n = 9) of recovery. At 3 and 7 days recovery, umbilical cord occlusion was associated with diffuse white matter injury, with loss of total and mature oligodendrocytes and reduced myelination in both the parietal and temporal lobes. At 14 days after umbilical cord occlusion, extensive microglial and astrocytic activation were observed in the temporal lobe. At 21 days recovery a spectrum of severe white matter degeneration was observed, including white matter atrophy, ventriculomegaly and overt cystic white matter lesions. The most severe injury was observed in the temporal lobe after 21 days recovery, including the majority of cystic lesions, persistent oligodendrocyte maturational arrest and impaired myelination. The spatial distribution of delayed white matter degeneration at 21 days recovery was closely related to the location of dense microglial aggregates at earlier time-points, implicating a role for exuberant inflammation originating from microglial aggregates in the pathogenesis of cystic white matter injury. The delayed appearance of cystic injury is consistent with continuing tertiary evolution of necrotic cell death. This slow evolution raises the tantalizing possibility that there may a relatively long therapeutic window to mitigate the development of cystic white matter injury. Delayed anti-inflammatory treatments may therefore represent a promising strategy to reduce neurodevelopmental disability in the preterm infants.