Neural tube defects (e.g., spina bifida, hydranencephaly) are a group of birth defects caused by incomplete development of the outer layers of the brain or spinal cord. Prenatal folate supplementation prevents an estimated 70 percent of neural tube defects, but additional therapies are needed. A recent report describes the relationship between maternal diabetes and abnormal cell aging in the fetal nervous system in mice.
Previous research has demonstrated a relationship between maternal diabetes and the incidence of neural tube defects in mice; however, the mechanisms that drive this relationship are unknown. High blood glucose levels cause oxidative damage and promote cellular senescence, a state in which cells are not metabolically active and do not reproduce. Aging cells accumulate damage over time and become senescent. In adults, an excess of senescent cells can promote inflammation and disease. In the developing fetus, senescence is vital for tissue remodeling and the building of limbs and organs. However, inappropriate senescence may lead to abnormal development.
The investigators used multiple mouse models in their study. In a first experiment, they used a strain of mice that develop diabetes and compared them to wild-type mice that are not predisposed to any disease. They injected pregnant females from both groups with either rapamycin, a compound that slows cellular aging by inhibiting the enzyme mTOR, or a placebo. In a second experiment, they used diabetic and non-diabetic strains of knockout mice, whose genomes do not contain the gene FoxO3a, a regulator of aging that may slow cellular senescence.
Maternal diabetes increased the abundance of biomarkers of cellular senescence and DNA damage in the lining of the brain in offspring. Pregnant diabetic mice that were exposed to rapamycin had offspring with lower levels of senescence biomarkers and fewer neural tube defects compared to placebo. Offspring from FoxO3a knockout mice experienced the same decrease in senescence biomarkers and neural tube defect rates as rapamycin-treated mice.
These results elucidate the mechanisms by which maternal diabetes can cause birth defects through metabolic changes that accelerate aging. Learn more about the role of cellular senescence in aging in this episode featuring Dr. Judith Campisi.
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