girl in hospital bed cutting hearts out of paper

Study suggests chronic hypoxia delays cardiac maturation in CHD

girl in hospital bed cutting hearts out of paper

Every year, nearly 40,000 babies are born with a congenital heart defect (CHD) — the leading cause of birth defect-associated infant illness and death.

Every year, nearly 40,000 babies are born with a congenital heart defect (CHD) — the leading cause of birth defect-associated infant illness and death. An event that may contribute to cyanotic CHD is the lack of oxygen, known as hypoxia, before and after birth, impacting gene expression and cardiac function that delay postnatal cardiac maturation, according to a new pre-clinical model led by researchers at Children’s National Hospital.

Single ventricle, transposition of the great arteries, truncus arteriosus and severe forms of tetralogy of Fallot, such cyanotic congenital heart diseases have lower circulating blood oxygen levels. The lack of oxygen in the blood begins prenatally and continues after birth until definitive repair, suggesting a delay on cardiac maturation.

There is little research on the underpinnings that explain the lack of oxygen’s effects on the developing heart, which could help inform adequate therapies in the pediatric population to promote cardiovascular health across the lifetime. The researchers developed the first pre-clinical model that explores the effects of chronic hypoxia in perinatal and postnatal stages on the developing heart under conditions seen in cyanotic CHD.

“To the best of our knowledge, ours is the first study to perform complete gene expression arrays on animals after perinatal hypoxia,” said Jennifer Romanowicz, senior noninvasive imaging fellow at Boston Children’s Hospital and lead author of the study. “Not only did these studies allow us to determine the effects of hypoxia on heart development, but the detailed results of our study will be available to other researchers to independently address other questions about perinatal hypoxia and heart development.”

The study published in the American Journal of Physiology: Heart and Circulatory Physiology suggests that chronic lack of oxygen alters the electrical properties of heart tissue, called the electrophysiological substrate, and the contractile apparatus, a muscle composed of proteins that control cardiac contraction. Multiple genes involved with the contractile apparatus were expressed differently in the non-human subjects.

“What was remarkable was that most abnormalities normalized after the animals recovered in normal oxygen levels,” said Romanowicz. “This is an optimistic sign that early repair of cyanotic congenital heart disease may allow the heart to finish development.”

The researchers placed pregnant non-human subjects in hypoxic chambers starting on embryonic day 16, mimicking the second trimester in humans. The same subjects gave birth in the hypoxic chambers, and the newborns were kept there until postnatal day eight when the heart muscle maturation is nearly complete. To understand how human infants recover with normalized oxygen levels after surgical repair of cyanotic CHD, the researchers moved hypoxic subjects to normal oxygen conditions for recovery and tested again at postnatal day 30.

“Next steps include using a pre-clinical model of cyanotic congenital heart disease that more accurately represents human neonatal physiology,” said Devon Guerrelli, Ph.D., candidate at Children’s National. We plan to work with the cardiac surgery team at Children’s National to investigate changes in the myocardium due to hypoxia in pediatric patients who are undergoing surgical repair.”

Nikki Posnack, Ph.D., principal investigator at Sheikh Zayed Institute for Pediatric Surgical Innovation and Nobuyuki Ishibashi, M.D., director of Cardiac Surgery Research Laboratory at Children’s National, led and guided the team of researchers involved in the study.

illustration of brain with stem cells

Innovative phase 1 trial to protect brains of infants with CHD during and after surgery

A novel phase 1 trial looking at how best to optimize brain development of babies with congenital heart disease (CHD) is currently underway at Children’s National Hospital.

Children with CHD sometimes demonstrate delay in the development of cognitive and motor skills. This can be a result of multiple factors including altered prenatal oxygen delivery, brain blood flow and genetic factors associated with surgery including exposure to cardiopulmonary bypass, also known as the heart lung machine.

This phase 1 trial is the first to deliver mesenchymal stromal cells from bone marrow manufactured in a lab (BM-MSC) into infants already undergoing cardiac surgery via cardiopulmonary bypass. The hypothesis is that by directly infusing the MSCs into the blood flow to the brain, more MSCs quickly and efficiently reach the subventricular zone and other areas of the brain that are prone to inflammation. The trial is open to eligible patients ages newborn to six months of age.

Learn more in this overview video.

The trial is part of a $2.5 million, three-year grant from the National Institutes of Health (NIH) led by Richard Jonas, M.D.Catherine Bollard, M.B.Ch.B., M.D., and Nobuyuki Ishibashi, M.D.. The project involves collaboration between the Prenatal Cardiology program of Children’s National Heart Institute, the Center for Cancer and Immunology Research, the Center for Neuroscience Research and the Sheikh Zayed Institute for Pediatric Surgical Innovation.

“NIH supported studies in our laboratory have shown that MSC therapy may be extremely helpful in improving brain development in animal models after cardiac surgery,” says Dr. Ishibashi. “MSC infusion can help reduce inflammation including prolonged microglia activation that can occur during surgery that involves the heart lung machine.”

Staff from the Cellular Therapy Laboratory, led by director Patrick Hanley, Ph.D., manufactured the BM-MSC at the Center for Cancer and Immunology Research, led by Dr. Bollard.

The phase 1 safety study will set the stage for a phase 2 effectiveness trial of this highly innovative MSC treatment aimed at reducing brain damage, minimizing neurodevelopmental disabilities and improving the postoperative course in children with CHD. The resulting improvement in developmental outcome and lessened behavioral impairment will be of enormous benefit to individuals with CHD.

For more information about this new treatment, contact the clinical research team: Gil Wernovsky, M.D., Shriprasad Deshpande, M.D., Maria Fortiz.

neuron on teal background

Primary cilia safeguard cortical neurons from environmental stress-induced dendritic degeneration

neuron on teal background

Fetus and neonates are under the risk of exposure to various external agents, such as alcohol and anesthetics taken by the mother. However, primary cilia can protect neurons by activating cilia-localized molecular signaling that inhibits degeneration of neuronal processes, according to the study’s findings.

A new study led by Kazue Hashimoto-Torii, Ph.D. and Masaaki Torii, Ph.D., both principal investigators for the Center for Neuroscience Research at Children’s National Hospital, found that primary cilia – tiny hair-like protrusions from the body of neuronal cells – protect neurons in the developing brain from adverse impacts of prenatal exposure.

Fetus and neonates are under the risk of exposure to various external agents, such as alcohol and anesthetics taken by the mother. However, primary cilia can protect neurons by activating cilia-localized molecular signaling that inhibits degeneration of neuronal processes, according to the study’s findings.

“Remarkably, the developing brain is equipped with intrinsic cell protection that helps to minimize the adverse impacts of to various external agents,” said Dr. Hashimoto-Torii. “However, the mechanisms of such protection have been unclear. Our study provides the first evidence that the tiny hair-like organelle protects neurons in the perinatal brain from adverse impacts of such external agents taken by the mother.”

The findings suggest that subtle alterations in primary cilia due to genetic conditions may lead to various neurodevelopmental disorders if combined with exposure to external agents from the environment. The findings also suggest that ciliopathy patients who have abnormal ciliary function due to genetic causes may have increased risk of abnormal brain development upon exposure to external agents.

“Clarifying diverse roles of cilia provides essential information for clinicians and patients with potential deficits in primary cilia to take extra precautions to avoid the risks for long-term negative impacts of external factors,” Dr. Torii explained. “We hope that further studies will define the whole picture of cilia-mediated neuroprotection and help us to advance our understanding of its importance in the pathogenesis of neurodevelopmental disorders.

This may ultimately lead to the development of treatment for various neurodevelopmental disorders,” he added.

The uniqueness of the study stems from the investigation of the role of cilia in brain development at the risk of exposure to various external factors that occur in the real world. Little is known about how the normal and abnormal brain development progresses in an environment where many external factors interact with intrinsic cellular mechanisms.

The study is a collaboration with researchers at Yale University and Keio University, Japan. Other Children’s National researchers who contributed to this study include Seiji Ishii, Ph.D.; Nobuyuki Ishibashi, M.D.; Toru Sasaki, M.D., Ph.D.; Shahid Mohammad, Ph.D.; Hye Hwang; Edwin Tomy; and Fahad Somaa.

doctors operating

U.S. DoD awards $2M for study to protect neurological function after cardiac surgery

doctors operating

A collaboration between clinical and basic science researchers including Drs. Ishibashi, Hashimoto-Torii, Jonas, and Deutsch, seeks to to understand how caspase enzyme activation plays a role in the development of fine and gross motor skills in children who underwent cardiac surgery for CHD repair.

The U.S. Department of Defense has awarded $2 million to Children’s National Hospital to study how a family of protease enzymes known as caspases may contribute to brain cell degeneration when activated by prolonged anesthesia and cardiopulmonary bypass during cardiac surgery for congenital heart disease.

This U.S. Army Medical Research Acquisition Activity Award, Anesthesia Neurotoxicity in Congenital Heart Disease, is led by principal investigator Nobuyuki Ishibashi, M.D., with both clinical and basic science co-investigators including Kazue Hashimoto-Torii, Ph.D., (Neuroscience), Richard Jonas, M.D., (Cardiovascular Surgery) and Nina Deutsch, M.D., (Anesthesiology).

While the specific cellular and molecular mechanisms of how anesthesia and cardiac surgery impact cortical development are poorly understood, both seem to impact brain growth and development in young children. The most common neurologic deficit seen in children after CHD surgical repair is the impairment of fine and gross motor skills.

Both anesthetic agents and inflammation like that seen as a result of cardiopulmonary bypass have also been shown to contribute to the activation of a specific group of enzymes that play an essential role in the routine (programmed) death of cells: caspases. However, recent pre-clinical research shows that these enzymes may also contribute to other alterations to cells beyond cell death, including making changes to other cell structures. In pre-clinical models, these changes cause impairments to fine and gross motor skills – the same neurological deficits seen in children with CHD who have undergone procedures requiring prolonged anesthesia and cardiopulmonary bypass.

The research team hypothesizes that caspases are extensively activated as a result of cardiac surgery and while that activation is rarely causing reduced numbers of neurons, the changes that caspase enzymes trigger in neurons are contributing to neurological deficits seen in children with CHD after surgery.

While the study focuses specifically on the impacts of cardiac surgery for correction of a heart defect, the findings could have major implications for any pediatric surgical procedure requiring prolonged anesthesia and/or cardiopulmonary bypass.

Nobuyuki Ishibashi

R01 grant funds white matter protection study for congenital heart disease

Nobuyuki Ishibashi

Nobuyuki Ishibashi, M.D., is the principal investigator on a $3.2 million NIH R01 to study white matter growth and repair in utero for fetal brains affected by congenital heart disease.

Many of the neurological deficits seen in children with congenital heart disease (CHD) are related to abnormal white matter development early in life caused by reduced oxygen supply to the brain while in utero. Children with immature white matter at birth also commonly sustain additional white matter injuries following cardiac surgery.

The NIH recently awarded a prestigious R01 grant totaling more than $3.2 million to a collaborative project led by the Center for Neuroscience Research, the Sheikh Zayed Institute for Pediatric Surgical Innovation and the Children’s National Heart Institute at Children’s National Hospital as well as MedStar Washington Hospital Center.

The research, titled “White matter protection in the fetus with congenital heart disease,” looks specifically at whether providing a supplemental amount of the naturally occurring tetrahydrobiopterin (BH4) for pregnant women could rescue white matter development of fetuses with congenital heart disease whose brains aren’t receiving enough oxygen – or suffering from hypoxic-ischemic events.

Previous preclinical studies have shown that this lack of oxygen depletes the brain’s natural BH4 level, and the researchers hypothesize that BH4 levels play a critical role in the growth and development of white matter in the fetal brain by triggering key cellular/molecular processes. Specifically, the study will focus on three aims:

  1. Establish in a preclinical model the optimal protective regiment for women pregnant with a fetus who has CHD to receive BH4.
  2. Determine the appropriate approach to deliver BH4 to this population
  3. Leverage genetic tools and biochemical techniques in the laboratory to better understand where and how BH4 levels play a role in the growth (or lack thereof) of oligodendrocytes—the primary cells of white matter.

This laboratory-based work is the first step to determining if the neurodevelopment of babies born with CHD can be preserved or recovered by addressing key brain development that occurs before the baby is even born. Findings related to congenital heart disease may also translate to other populations where white matter development is affected by hypoxia-ischemia, including premature infants.

The project is led by principal investigator Nobuyuki Ishibashi, M.D., with co-investigators Vittorio Gallo, Ph.D., Joseph Scafidi, D.O., and Mary Donofrio, M.D. as well as colleagues at MedStar Washington Hospital Center.

Newborn baby laying in crib

Can cells collected from bone marrow stimulate generation of new neurons in babies with CHD?

Newborn baby laying in crib

The goal of the study will be to optimize brain development in babies with congenital heart disease (CHD) who sometimes demonstrate delay in the development of cognitive and motor skills.

An upcoming clinical trial at Children’s National Hospital will harness cardiopulmonary bypass as a delivery mechanism for a novel intervention designed to stimulate brain growth and repair in children who undergo cardiac surgery for congenital heart disease (CHD).

The NIH has awarded Children’s National $2.5 million to test the hypothesis that mesenchymal stromal cells (MSCs), which have been shown to possess regenerative properties and the ability to modulate immune responses in a variety of diseases, collected from allogeneic bone marrow, may promote regeneration of damaged neuronal and glial cells in the early postnatal brain. If successful, the trial will determine the safety of the proposed treatment in humans and set the stage for a Phase 2 efficacy trial of what could potentially be the first treatment for delays in brain development that happen before birth as a consequence of congenital heart disease. The study is a single-center collaboration between three Children’s National physician-researchers: Richard Jonas, M.D.Catherine Bollard, M.B.Ch.B., M.D. and Nobuyuki Ishibashi, M.D.

Dr. Jonas, chief of cardiac surgery at Children’s National, will outline the trial and its aims on Monday, November 18, 2019, at the American Heart Association’s Scientific Sessions 2019. Dr. Jonas was recently recognized by the Cardiac Neurodevelopmental Outcome Collaborative for his lifelong research of how cardiac surgery impacts brain growth and development in children with CHD.

Read more about the study: Researchers receive $2.5M grant to optimize brain development in babies with CHD.


Regenerative Cell Therapy in Congenital Heart Disease – Protecting the Immature Brain
Presented by Richard Jonas, M.D.
AHA Scientific Sessions
Session CH.CVS.608 Congenital Heart Disease and Pediatric Cardiology Seminar: A Personalized Approach to Heart Disease in Children
9:50 a.m. to 10:05 a.m.
November 18, 2019