Tag Archive for: neurodevelopmental delay

caspase molecule

Caspases may link brain cell degeneration and cardiac surgery

caspase molecule

The review summarizes both the known physiological roles of caspases as well as some of the well-characterized neurotoxic effects of anesthetics in pre-clinical models.

A review article in the journal Cell Press: Trends in Neuroscience outlines the wide variety of cellular signaling roles for caspase proteins — a type of cellular enzyme best known for its documented role in the natural process of cell death (apoptosis). The authors, including Nemanja Saric, Ph.D., Kazue Hashimoto-Torii, Ph.D., and Nobuyuki Ishibashi, M.D., all from Children’s National Research Institute, pay particular attention to what the scientific literature shows about caspases’ non-apoptotic roles in the neurons specifically. They also highlight research showing how, when activated during a cardiac surgery with anesthesia and cardiopulmonary bypass, these enzymes may contribute to the degeneration of brain cells seen in young children who undergo heart surgery for critical congenital heart defects (CHDs).

Why it matters

The review summarizes both the known physiological roles of caspases as well as some of the well-characterized neurotoxic effects of anesthetics in pre-clinical models.

The authors propose that these non-apoptotic activities of caspases may be behind some of the adverse effects on the developing brain related to cardiac surgery and anesthesia. Those adverse effects are known to increase risk of behavioral impairments in children with congenital heart disease who underwent cardiac surgery with both anesthesia and cardiopulmonary bypass at a very young age.

This work is the first to propose a possible link between developmental anesthesia neurotoxicity and caspase-dependent cellular responses.

The patient benefit

Better understanding of the time and dose-dependent effects of general anesthetics on the developing brain, particularly in children who have genetic predispositions to conditions such as CHDs, will help researchers understand their role (if any) in behavioral problems often encountered by these patients after surgery.

If found to be a contributing factor, perhaps new therapies to mitigate this caspase activity might be explored to alleviate some of these adverse effects on the developing brain.

What’s next?

The authors hope to stimulate more in-depth research into caspase signaling events, particularly related to how these signaling events change when an anesthetic is introduced. Deeper understanding of how anesthetics impact caspase activation in the developing brain will allow for better assessments of the risk for children who need major surgery early in life.

Children’s National leads the way

Children’s National Hospital leads studies funded by the U.S. Department of Defense to better understand how these other roles of caspases, which until now have not been well-documented, may contribute to brain cell degeneration when activated by prolonged anesthesia and cardiopulmonary bypass during cardiac surgery for congenital heart disease.

Nobuyuki Ishibashi

Children’s receives NIH grant to study use of stem cells in healing CHD brain damage

Nobuyuki Ishibashi

“Bone marrow stem cells are used widely for stroke patients, for heart attack patients and for those with developmental diseases,” explains Nobuyuki Ishibashi, M.D. “But they’ve never been used to treat the brains of infants with congenital heart disease. That’s why we are trying to understand how well this system might work for our patient population.”

The National Institutes of Health (NIH) awarded researchers at Children’s National Health System $2.6 million to expand their studies into whether human stem cells could someday treat and even reverse neurological damage in infants born with congenital heart disease (CHD).

Researchers estimate that 1.3 million infants are born each year with CHD, making it the most common major birth defect. Over the past 30 years, advances in medical technology and surgical practices have dramatically decreased the percentage of infants who die from CHD – from a staggering rate of nearly 100 percent just a few decades ago to the current mortality rate of less than 10 percent.

The increased survival rate comes with new challenges: Children with complex CHD are increasingly diagnosed with significant neurodevelopmental delay or impairment. Clinical studies demonstrate that CHD can reduce oxygen delivery to the brain, a condition known as hypoxia, which can severely impair brain development in fetuses and newborns whose brains are developing rapidly.

Nobuyuki Ishibashi, M.D., the study’s lead investigator with the Center for Neuroscience Research and director of the Cardiac Surgery Research Laboratory at Children’s National, proposes transfusing human stem cells in experimental models through the cardio-pulmonary bypass machine used during cardiac surgery.

“These cells can then identify the injury sites,” says Dr. Ishibashi. “Once these cells arrive at the injury site, they communicate with endogenous tissues, taking on the abilities of the damaged neurons or glia cells they are replacing.”

“Bone marrow stem cells are used widely for stroke patients, for heart attack patients and for those with developmental diseases,” adds Dr. Ishibashi. “But they’ve never been used to treat the brains of infants with congenital heart disease. That’s why we are trying to understand how well this system might work for our patient population.”

Dr. Ishibashi says the research team will focus on three areas during their four-year study – whether the stem cells:

  • Reduce neurological inflammation,
  • Reverse or halt injury to the brain’s white matter and
  • Help promote neurogenesis in the subventricular zone, the largest niche in the brain for creating the neural stem/progenitor cells leading to cortical growth in the developing brain.

At the conclusion of the research study, Dr. Ishibashi says the hope is to develop robust data so that someday an effective treatment will be available and lasting neurological damage in infants with congenital heart disease will become a thing of the past.