Its long been known that breastfeeding passes valuable protection from the mother to her child, but there are other unique cells that prevent passing harmful viruses from the mother to her unborn child; researchers at Magee-Women’s Research Institute and the University of Pittsburgh School of Medicine have found that cells in the placenta can prevent unborn children from becoming infected with viruses from their mother.

Though the research suggests that it is the placenta that is keeping the child safe from viruses, the research team is still unclear as to how this actually happens. Up until the study, it was usually thought that the placenta was just a barrier between a fetus and its mother, but now it could be something much more important and necessary for the development of the fetus. "Our findings reveal some of the complex and elegant mechanisms human placental cells, called trophoblasts, have evolved to keep viruses from infecting cells," said Dr. Sadovsky, the lead researcher for the study. "We hope that we can learn from this to devise new therapies against viral infections."

The findings that the research team uncovered were a result of studying human trophoblast cells and exposing them to a panel of viruses. Unlike non-placental cells, trophoblasts were resistant to viral infection. However, that characteristic was not a result of an inability of viruses to bind or enter the cells. The research team noticed that when the medium, or fluid environment, into which the trophoblasts were cultured was transferred to non-placental cells like those that line blood vessels, they became resistant to viral infection as well.

During these tests, the researchers observed that when the medium was exposed to sonication, or exposure to sound waves, viral resistance was no longer transferred to non-placental cells. This finding led them to take a closer look at tiny spheres called nanovesicles that are secreted by trophoblasts and are sensitive to sonication, they are also called exosomes. The team found that bits of genetic material called microRNAs contained within the exosomes were able to induce autophagy, which is a process of prolonged cellular recycling and survival. By blocking autophagy, vulnerability to viral infections moderately restored the cells.

The data collected from the research has led the team to believe that there could be ways of protecting fetuses from viruses in more efficient ways. Co-senior investigator of the study, Dr. Coyne, even believes that "we might be able to use these microRNAs to reduce the risk of viral infection in other cells outside of pregnancy, or perhaps to treat diseases where enhancing autophagy would be beneficial."



  • Elizabeth Delorme-Axford, Et al. Human placental trophoblasts confer viral resistance to recipient cells. PNAS, 2013 DOI: 10.1073/pnas.1304718110
  • University of Pittsburgh Schools of the Health Sciences (2013, July 1). Placental cells may prevent viruses from passing from mother to baby. Science Daily.
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