Pediatric neurologists have a long-held belief that low blood flow to the premature brain kills brain cells, causing disabilities.
Research by physician-scientists at Oregon Health & Science University Doernbecher Children's Hospital are challenging this way of thinking, opening the door to new treatments that could regenerate and repair the premature brain.
Contrary to previous thought by neurologists, the study found that low blood and oxygen flow to the developing brain does not cause an irreversible loss of brain cells such as neurons, the specialized cells that make up the body’s nervous system. Instead, this condition, known as ischemia, disrupts the cell’s ability to mature fully.
“As neurologists, we thought ischemia killed the neurons and that they were irreversibly lost from the brain, but this new data challenges that notion by showing that ischemia, or low blood flow to the brain, can alter the maturation of the neurons without causing the death of these cells,” said Stephen Back, M.D., Ph.D., lead investigator and professor of pediatrics and neurology in the Papé Family Pediatric Research Institute at OHSU Doernbecher Children’s Hospital.
“As a result, we can focus greater attention on developing the right interventions at the right time early in development to promote neurons to more fully mature and reduce the often serious impact of preterm birth. We now have a much more hopeful scenario.”
Several studies used preterm fetal sheep to determine how disturbances in brain blood flow injured the eveloping brain. The team developed new MRI studies that enabled medical professionals to identify brain injury earlier than current techniques. They looked at the “thinking” part of the brain, the cerebral cortex, which controls complex tasks such as attention, social, and learning behaviors. These behaviors are often impaired in premature babies with disturbed blood flow.
When researchers studied the cerebral cortex of fetal sheep over one month, they found no evidences that cells brain cells were dying or lost. They observed that the brain cells were not fully mature and were packed in smaller volumes than normal cells.
A related study by researchers at The Hospital for Sick Children and the University of Toronto studied 95 premature infants using MRI. They found that the impaired growth of the infants was the strongest predictor of MRI abnormalities. The results suggest that interventions designed to improve infant nutrition and growth may promote improvements in cortical development.
“I believe these studies provide hope for the future for preterm babies with brain injury, because our findings suggest that neurons are not being permanently lost from the human cerebral cortex due to ischemia. This raises the possibility that neurodevelopmental enrichment - or perhaps improved early infant nutrition - as suggested by the companion paper, might make a difference in terms of improved cognitive outcome,” Back said.
“Together, these studies challenge the conventional wisdom that preterm birth is associated with a loss of cortical neurons. This finding may change the way neurologists think about diagnosing and treating children born prematurely,” said Jill Morris, Ph.D., a program director at the National Institute’s of Health’s National Institute Neurological Disorders and Stroke.
Children who are born prematurely may have life-long disabilities such as cerebral palsy. When they reach school age 25 to 50 percent of children born prematurely may have learning disabilities, attention deficit disorders, and impaired social development.
Both studies are published online in the Jan. 16 issue of Science Translational Medicine.