IGF2 Signal Helps Regulate Fetal Growth and Placenta Expansion

Scientists at the University of Cambridge scientists have identified a key signal that the fetus uses to control its supply of nutrients from the placenta, revealing a tug-of-war between genes inherited from the father and from the mother. The study was published in Developmental Cell. 

The scientists used genetically engineered mice to show how the fetus produces a signal to encourage the growth of blood vessels within the placenta. This signal also causes modifications to other cells of the placenta to allow for more nutrients from the mother to go through to the fetus. "We’ve identified one way that the fetus uses to communicate with the placenta to prompt the correct expansion of these blood vessels," said lead researcher Ionel Sandovici. "When this communication breaks down, the blood vessels don’t develop properly and the baby will struggle to get all the food it needs."

The team found that the fetus sends a signal known as IGF2 that reaches the placenta through the umbilical cord. In humans, levels of IGF2 in the umbilical cord progressively increase between 29 weeks of gestation and term: too much IGF2 is associated with too much growth, while not enough IGF2 is associated with too little growth. Sandovici added, “We’ve known for some time that IGF2 promotes the growth of the organs where it is produced. In this study, we’ve shown that IGF2 also acts as a classical hormone—it’s produced by the fetus, goes into the fetal blood, through the umbilical cord, and to the placenta."

The team says their findings will allow a better understanding of how the fetus, placenta, and mother communicate with each other during pregnancy. This in turn could lead to ways of measuring levels of IGF2 in the fetus and finding ways to use medication to normalize these levels or promote normal development of placental vasculature.