Researchers Find Placenta Blocks Viruses between Mother and Unborn Baby

Jul 2, 2013

When virologist and mother-to-be Carol Coyne was working in her lab four years ago, she began wondering how her placenta was protecting her unborn baby from the viruses she worked with.

At that time, placenta was seen as a passive barrier between a mother and her unborn child, but four years later, Coyne and director of Magee Woman’s Research Institute Yoel Sadovsky have uncovered a new purpose for it.

Sadovsky and Coyne have found that the cells in placenta, called trophoblasts, actually block viruses from crossing from the mother to her baby.

According to the researchers, trophoblasts have a mechanism that resists viruses that normally affect other cell types in the body.

Sadovsky and Coyne said viruses can still get into the placental cells, but they do not multiply like they do in other cells.

“We have found in the placental cells that although the viruses can bind and enter the cells quite well, they can never get into the process of replicating themselves and so they don’t grow and because of that, very quickly, they are cleared from the placental cells and essentially they are completely protected from infection,” Coyne said.

The investigators then found that they were able to transfer that resistance to other cell types in the body when the cells were exposed to the fluid environment where the trophoblasts were cultured.

Coyne and Sadovsky then looked closer into secretions by the trophoblasts and found the microRNA was able to induce autophagy, which is a method of cellular recycling and survival.

But when autophagy was interrupted, the cells became at least partially vulnerable to viruses again.

Sadovsky said the placental cells’ resistance could be an evolutionary adaptation found only in humans and monkeys.

“The placenta is the mediator of any interaction between the mother and the fetus and if the placenta can release protection factors that can terminate viral infections in other cell types, that factor can potentially be released to the mother and to the embryo (and) thereby protect their tissues from viral infections,” Sadovsky said.

The researchers hope to find a way to use their discoveries to combat the risk of viral infection in other cells outside of pregnancy and treat other diseases.