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Nickie Andescavage

To understand the preterm brain, start with the fetal brain

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Nickie Andescavage

“My best advice to future clinician-scientists is to stay curious and open-minded; I doubt I could have predicted my current research interest or described the path between the study of early oligodendrocyte maturation to in vivo placental development, but each experience along the way – both academic and clinical – has led me to where I am today,” Nickie Andescavage, M.D., writes.

Too often, medical institutions erect an artificial boundary between caring for the developing fetus inside the womb and caring for the newborn whose critical brain development continues outside the womb.

“To improve neonatal outcomes, we must transform our current clinical paradigms to begin treatment in the intrauterine period and continue care through the perinatal transition through strong collaborations with obstetricians and fetal-medicine specialists,” writes Nickie Andescavage, M.D., an attending in Neonatal-Perinatal Medicine at Children’s National.

Dr. Andescavage’s commentary was published online March 25, 2019, in Pediatrics Research and accompanies recently published Children’s research about differences in placental development in the setting of placental insufficiency. Her commentary is part of a new effort by Nature Publishing Group to spotlight research contributions from early career investigators.

The placenta, an organ shared by a pregnant woman and the developing fetus, plays a critical but underappreciated role in the infant’s overall health. Under the mentorship of Catherine Limperopoulos, Ph.D., director of MRI Research of the Developing Brain, and Adré J. du Plessis, M.B.Ch.B., MPH, chief of the Division of Fetal and Transitional Medicine, Dr. Andescavage works with interdisciplinary research teams at Children’s National to help expand that evidence base. She has contributed to myriad published works, including:

While attending Cornell University as an undergraduate, Dr. Andescavage had an early interest in neuroscience and neurobehavior. As she continued her education by attending medical school at Columbia University, she corroborated an early instinct to work in pediatrics.

It wasn’t until the New Jersey native began pediatric residency at Children’s National that those complementary interests coalesced into a focus on brain autoregulation and autonomic function in full-term and preterm infants and imaging the brains of both groups. In normal, healthy babies the autonomic nervous system regulates heart rate, blood pressure, digestion, breathing and other involuntary activities. When these essential controls go awry, babies can struggle to survive and thrive.

“My best advice to future clinician-scientists is to stay curious and open-minded; I doubt I could have predicted my current research interest or described the path between the study of early oligodendrocyte maturation to in vivo placental development, but each experience along the way – both academic and clinical – has led me to where I am today,” Dr. Andescavage writes in the commentary.

Vittorio Gallo

Neurodevelopmental disorders: Developing medical treatments

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Vittorio Gallo

Vittorio Gallo, Ph.D., Chief Research Officer, participates in the world’s largest general scientific gathering, leading panelists in a timely conversation about progress made so far with neurodevelopmental disorders and challenges that lie ahead.

The human brain is the body’s operating system. Imagine if rogue code worked its way into its hardware and software, delaying some processes, disrupting others, wreaking general havoc.

Neurodevelopmental disorders are like that errant code. They can occur early in life and impact brain development for the rest of the person’s life. Not only can fundamental brain development go awry, processes that refine the brain also can become abnormal, creating a double neural hit.  Adding to those complications, children with neurodevelopmental disorders like autism spectrum disorder (ASD) and Fragile X syndrome often contend with multiple, overlapping cognitive impairments and learning disabilities.

The multiple layers of complexities for these disorders can make developing effective medical treatments particularly challenging, says Vittorio Gallo, Ph.D., Chief Research Officer at Children’s National Health System and recipient of a coveted Senator Jacob Javits Award in the Neurosciences.

During the Feb. 16, 2019, “Neurodevelopmental Disorders: Developing Medical Treatments” symposium, Gallo will guide esteemed panelists in a timely conversation about progress made so far and challenges that lie ahead during the AAAS Annual Meeting in Washington, the world’s largest general scientific gathering.

“This is a very important symposium; we’re going to put all of the open questions on the table,” says Gallo. “We’re going to present a snapshot of where the field is right now: We’ve made incredible advances in developmental neuroscience, neonatology, neurology, diagnostic imaging and other related fields. The essential building blocks are in place. Where are we now in developing therapeutics for these complex disorders?”

For select disorders, many genes have been identified, and each new gene has the potential to become a target for improved therapies. However, for other neurodevelopmental disorders, like ASD, an array of new genes continue to be discovered, leaving an unfinished picture of which genetic networks are of most importance.

Gallo says the assembled experts also plan to explore major research questions that remain unanswered as well as how to learn from past experiences to make future studies more powerful and insightful.

“One topic up for discussion will be new preclinical models that have the potential to help in identifying specific mechanisms that cause these disorders. A combination of genetic, biological, psychosocial and environmental risk factors are being combined in these preclinical models,” Gallo says.

“Our studies of the future need to move beyond describing and observing in order to transform into studies that establish causality between the aberrant developmental processes and these constellations of neurodevelopmental disorders.”

Vittorio Gallo

How the environment helps to shape the brain

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Vittorio Gallo

“The strength, duration and timing of environmental experience influences plasticity in brain circuitry, which is made up of communication cables called axons that link neurons throughout the brain and are coated by myelin, a fatty substance that helps nerve impulses speed from place to place,” says Vittorio Gallo, Ph.D., Chief Research Officer at Children’s National and senior study author.

Researchers have long known that babies of all kinds need to be exposed to rich, complex environments for optimal brain health and potential. Exposure to new sights, sounds and other sensory experiences appears to be critical for strengthening infants’ developing brains and encouraging smoothly running neural networks. Until recently, little was known about the biological mechanisms behind this phenomenon.

In a review article published online Aug. 22, 2017 in Trends in Neurosciences, Children’s National Health System researchers discuss the role of environmental stimuli on the development of myelin—the fatty insulation that surrounds the extensions that connect cells throughout the nervous system and make up a large part of the brain’s white matter. Positive influences, such as exposure to a large vocabulary and novel objects, can boost the growth of myelin. Conversely, negative influences, such as neglect and social isolation, can harm it, potentially altering the course of brain development.

“The strength, duration and timing of environmental experience influences plasticity in brain circuitry, which is made up of communication cables called axons that link neurons throughout the brain and are coated by myelin, a fatty substance that helps nerve impulses speed from place to place,” says Vittorio Gallo, Ph.D., Chief Research Officer at Children’s National and senior study author. “As it responds to environmental stimuli, the brain continually shores up myelin’s integrity. Just as important, damaged myelin can leave gaps in the neural network which can lead to cognitive, motor and behavioral deficits.”

According to Gallo and study lead author Thomas A. Forbes, a pool of oligodendrocyte progenitor cells (OPCs) specialize in making myelin and do so from childhood into adulthood. The resulting oligodendrocyte cells (OLs) form an important working partnership with axons. From approximately 23 to 37 weeks’ gestation, OLs develop in the fetal brain and they continue to be generated after birth until adolescence.

“This dynamic feedback loop between myelin plasticity and neuronal excitability is crucial,” Forbes says. “It helps to strengthen motor and cognitive function and permits children and adults to learn new skills and to record new memories.”

In utero, genetics plays an outsized role in the initial structure of white matter, which is located in the subcortical region of the brain and takes its white color from myelin, the lipid and protein sheath that electrically insulates nerve cells. Defects in the microstructural organization of white matter are associated with many neurodevelopmental disorders. Once infants are born, environmental experiences also can begin to exert a meaningful role.

“The environment can be viewed as a noninvasive therapeutic approach that can be employed to bolster white matter health, either on its own or working in tandem with pharmacologic therapies,” Gallo adds. “The question is how to design the best environment for infants and children to grow and to achieve the highest cognitive function. An enriched environment not only involves the opportunity to move and participate in physical exercise and physical therapy; it is also an environment where there is novelty, new experiences and continuously active learning. It is equally important to minimize social stressors. It’s all about the balance.”

Among the potential interventions to boost brain power, independent of socioeconomic status:

  • Exposing children to new and different objects with an opportunity for physical activity and interaction with a number of playmates. This type of setting challenges the child to continuously adapt to his or her surroundings in a social, physical and experiential manner. In experimental models, enriched environments supported brain health by increasing the volume and length of myelinated fibers, the volume of myelin sheaths and by boosting total brain volume.
  • Exposure to music helps with cognition, hearing and motor skills for those who play an instrument, tapping multiple areas of the brain to work together collaboratively. Diffusion tensor imaging (DTI) reveals that professional pianists who began playing as children have improved white matter integrity and plasticity, Gallo and Forbes
  • At its heart, active learning requires interacting with and adapting to the environment. Generating new OLs influences learning new motor skills in the very young as well as the very old. And cognitive training and stimulation shapes and preserves white matter integrity in the aging.
  • DTI studies indicate that four weeks of integrative mind-body training alters myelination and improves white matter efficiency with especially pronounced changes in the area of the brain responsible for self-regulation, impulse control and emotion.
  • Voluntary exercise in experimental models is associated with OPCs differentiating into mature OLs. Imaging studies show a positive relationship between physical fitness, white matter health and the brain networks involved in memory.

Conversely, such negative influences as premature birth, poor nutrition, disease, neglect and social isolation can degrade myelin integrity, compromising the person’s ability to carry out basic motor skills and cognitive function. Usually, the pool of OPCs expands as the fetus is about to be born. But brain injury, lack of oxygen and restricted blood supply can delay maturation of certain brain cells and can cause abnormalities in white matter that diminish the brain’s capacity to synthesize myelin. Additional white matter insults can be caused by use of anesthesia and stress, among other variables.

The environmental influence has the potential to be “the Archimedes’ Lever to appropriating WM development among a limited range of only partially efficacious treatment options,” the authors conclude.

Premature birth may alter critical cerebellar development linked to learning and language

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Diffusion tensor imaging teases out subtle injury to cerebral and cerebellar white matter that is not evident with conventional MRI, allowing researchers to quantify brain tissue microstructure and classify white matter integrity.

Diffusion tensor imaging teases out subtle injury to cerebral and cerebellar white matter that is not evident with conventional MRI, allowing researchers to quantify brain tissue microstructure and classify white matter integrity.

Premature birth can interrupt a key period of brain development that occurs in the third trimester, which has the potential to impact a child’s long-term learning, language, and social skills. A recent case-control study published in The Journal of Pediatrics applied diffusion tensor magnetic resonance imaging (DTI) to zoom in on the microstructures comprising the critical cerebellar neural networks related to learning and language, and found significant differences between preterm and full-term newborns.

“The third trimester, during which many premature births occur, is typically when the developing cerebellum undergoes its most dramatic period of growth. Normally, the cerebellar white matter tracts that connect to the deep nuclei are rich in pathways where nerve fibers cross. Those connections permit information to flow from one part of the brain to another. It is possible that premature birth leads to aberrant development of these critical neural networks,” says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National Health System and senior study author.

One in 10 American babies is born prematurely. The brain injury that infants born prematurely experience is associated with a range of neurodevelopmental disabilities, including some whose influence isn’t apparent until years later, when the children begin school. Nearly half of extremely preterm infants go on to experience long-term learning, social, and behavioral impairments.

While conventional magnetic resonance imaging (MRI) can detect many brain abnormalities in newborns, a newer technique called DTI can tease out even subtle injury to cerebral and cerebellar white matter that is not evident with conventional MRI. White matter contains axons, which are nerve fibers that transmit messages. With DTI, researchers can quantify brain tissue microstructure and describe the integrity of white matter.

The research team compared imaging from 73 premature infants born before 32 weeks gestation who weighed less than 1,500 grams with 73 healthy newborns born to mothers who delivered at full term after 37 weeks. After the newborns had been fed, swaddled, and fitted with double ear protection, the imaging was performed as they slept. Nurses monitored their heart rates and oxygen saturation. Their brain abnormalities were scored as normal, mild, moderate, or severe.

All of the full-term newborns had normal brain MRIs as did 44 (60.3 percent) of the preemies.

The preemies had significantly higher fractional anisotropy in the cerebellum, the part of the brain that processes incoming information from elsewhere in the brain, permitting coordinated movement as well as modulating learning, language, and social skills. Alterations in cerebellar microarchitecture was associated with markers for illness severe enough to require surgery – such as correcting abnormal blood flow caused by the failure of the ductus arteriosus to close after birth and to remedy a bowel disease known as necrotizing enterocolitis. The risk factors also are associated with compromised cardiorespiratory function and low Apgar score at five minutes, Limperopoulos and co-authors write. The Apgar score is a quick way to gauge, one minute after birth, how well the newborn withstood the rigors of childbirth. It is repeated at five minutes to describe how the newborn is faring outside of the womb.

“In previous studies, we and others have associated cerebellar structural injury in preterm infants with long-term motor, cognitive, and socio-affective impairments. This is one of the first studies to provide a detailed report about these unexpected alterations in cerebellar microstructural organization,” she adds. “We postulate that the combination of premature birth and early exposure of the immature developing cerebellum to the extrauterine environment results in disturbed micro-organization.”

Additional research is warranted in larger groups of patients as well as long-term follow up of this cohort of newborns to determine whether this microstructural disorganization predicts long-term social, behavioral, and learning impairments.

“A large number of these prematurely born newborns had MRI readings in the normal range. Yet, we know that these children are uniquely at risk for developing neurodevelopmental disabilities later in life. With additional study, we hope to identify interventions that could lower those risks,” Limperopoulos says.

Related resources: The Journal of Pediatrics editorial

Every day fetuses remain in utero critical to preserving normal brain development

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If it does not jeopardize the health of the pregnant mother or her fetus, pregnancies should be carried as close to full term as possible to avoid vulnerable preemies experiencing a delay in brain development, study results published October 28 in Pediatrics indicate.

Some 15 million infants around the world – and 1 in 10 American babies – are born prematurely. While researchers have known that preemies’ brain growth is disturbed when compared with infants born at full term, it remained unclear when preemies’ brain development begins to veer off course and how that impairment evolves over time, says Catherine Limperopoulos, Ph.D., Director of the Developing Brain Research Laboratory at Children’s National Health System and senior study author.

A look at the research

In order to shine a spotlight on this critical phase of fetal brain development, Limperopoulos and colleagues studied 75 preterm infants born prior to the 32th gestational week who weighed less than 1,500 grams who had no evidence of structural brain injury. These preemies were matched with 130 fetuses between 27 to 39 weeks gestational age.

The healthy fetal counterparts are part of a growing database that the Children’s National Developing Brain Research Laboratory has assembled. The research lab uses three-dimensional magnetic resonance imaging to carefully record week-by-week development of the normal in utero fetal brains as well as week-by-week characterizations of specific regions of the fetal brain.

The availability of time-lapsed images of normally developing brains offers a chance to reframe research questions in order to identify approaches to prevent injuries to the fetal brain, Limperopoulos says.

“Up until now, we have been focused on examining what is it about being born too early? What is it about those first few hours of life that leaves preemies more vulnerable to brain injury?” she says. “What is really unique about these study results is for the very first time we have an opportunity to better understand the ways in which we care for preemies throughout their hospitalization that optimize brain development and place more emphasis those activities.”

When the research team compared third-trimester brain volumes, preemies showed lower volumes in the cerebrum, cerebellum, brainstem, and intracranial cavity. The cerebrum is the largest part of the brain and controls speech, thoughts, emotions, learning, as well as muscle function. The cerebellum plays a role in learning and social-behavioral functions as well as complex motor functions; it also controls the balance needed to stand up and to walk. The brainstem is like a router, ferrying information between the brain, the cerebellum, and the spinal cord.

“What this study shows us is that every day and every week of in utero development is critical. If at all possible, we need to keep fetuses in utero to protect them from the hazards that can occur in the extra uterine environment,” she says.

Exploration of the developing brain

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Common, lifelong health conditions like diabetes and hypertension have footprints that can be traced back to the womb. With advanced fetal MRI we seek to understand as much as possible about brain development during the time in utero. Non-invasive imaging technology helps us to identify signs of abnormal fetal development that may facilitate earlier diagnoses of chronic conditions and intervention.

We’re exploiting both the power and safety of MRI to develop ways to pick up early signs and signals in fetuses whose brain development may be veering off in the wrong direction. Using this advanced technology we can begin to detect varying signals or other signs of distress. These signs of distress may appear in the form of a brain chemical imbalance or a structural brain abnormality that is too subtle to be seen by an ultrasound or other scan. We now have the ability to leverage magnetic resonance imaging to examine the brain in utero for even the most subtle derailments that can lead to lifelong consequences.

The first nine months of life, when a fetus is in the womb, is a time of unparalleled growth and a critical time for fetal brain development. As we examine the maturation of the fetal brain, we know that each and every cortical fold represents future function lost or gained and lays the fundamental background or platform from which critical functions will emerge such as language and social and behavioral development.

We are developing technology that can quickly and reliably pick up early signals of a fetal brain that’s going off route to provide the ability to access therapeutic windows that are currently inaccessible. Earlier identification and intervention can improve the quality of life for children and potentially could even reverse the abnormality.

Early identification of fetal distress is critical. To be able to provide an intervention you must first be able to know that a fetus is getting into trouble, and you must be able to identify the problem early enough, in order to intervene before it has already caused injury to the fetus.

About the Author

Catherine LimperopoulosCatherine Limperopoulos, Ph.D.
Director, MRI Research of the Developing Brain; Director, Diagnostic Imaging and Radiology/Fetal and Transitional Medicine
Research interests: Fetal neonatal brain injury

Fetal medicine update: fetal brain development, zika virus

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May 2, 2016 –Impaired global and tissue-specific brain development in the growth-restricted fetus.
A team of researchers applied an advanced imaging technique, three-dimensional MRI, to study brain development in high-risk pregnancies and are the first to report regional, tissue-specific volume delays for the developing fetal brain in FGR-affected pregnancies. The team compared overall fetal brain volume as well as regional brain volumes for a control group of healthy young pregnant women with a group of young women whose pregnancies were complicated by FGR. While fetuses in both groups grew exponentially as pregnancies progressed, the researchers began to see dramatic differences when they compared the volumes of specific regions of the brain, including the cerebellum, which coordinates balance and smooth movement; the deep gray matter, which also is involved in complex functions, such as memory and emotion; and the white matter, which is made up of millions of nerve fibers that connect to neurons in different regions.

March 30, 2016 – Congenital Zika viral infection linked to significant fetal brain abnormalities, despite ‘normal’ ultrasounds.
Infectious Zika virus was isolated from the brain of a 21-week-old fetus after causing extensive damage to brain tissue – despite ultrasounds that showed no sign of microcephaly at weeks 13, 16, and 17, according to a report published online in The New England Journal of Medicine. “While this is a single case, it poses troubling questions that could inform future research,” says the study’s co-senior author, Adre du Plessis, M.B.Ch.B., Director of the Fetal Medicine Institute and Chief of the Fetal and Transitional Medicine Division at Children’s National Health System. “Evidence is mounting that the Zika virus can persist in pregnant women’s bloodstreams weeks after their initial infection, arguing for changes to how these pregnancies are monitored,” Dr. du Plessis said. Six of the named authors are affiliated with Children’s National, where the pregnant woman sought more thorough assessment after testing positive for the Zika virus herself following international travel.