Human life begins with a single egg that grows into a human being with trillions of cells. To ensure that the complex development of tissues and organs is as protected as possible, the placental barrier keeps pathogens and foreign substances out. Tina Bürki and her team at Empa’s Biology and Particle Interactions laboratory in St. Gallen are investigating how this protective mechanism copes with nanoparticles.
Nanoparticles are contained in a large number of products, but they are also produced during wear and through combustion processes (see box). “We absorb these substances from the environment through our food, cosmetics or the air we breathe,” explains Bürki. Some of these nanoparticles are suspected of harming babies in the womb. Among the possible consequences for the child are low birth weight, autism and respiratory diseases.
Mysterious remote effect
It is still unclear how nanoparticles affect the fetus. “We already know that the placental barrier retains many nanoparticles or at least delays their transport to the embryo,” says Bürki. However, damage to fetal tissue occurs even if no particles have been detected in the fetus. The Empa team is now getting to the bottom of this long-range effect of nanoparticles. Together with clinical partners from the Cantonal Hospital of St. Gallen and research partners from the University of Geneva, the University Medical Center of Amsterdam and the Leibniz Institute for Environmental Medical Research in Düsseldorf, the team is investigating the consequences of common nanoparticles such as titanium dioxide. or diesel soot on the function of the placenta and its indirect damage to embryonic development.
To do this, the team used fully functional human placentas that became available after a planned cesarean section. “Human placental tissue is the only way to obtain significant results on the transport and effect of nanoparticles,” says the Empa researcher. “The structure, metabolism and interaction of maternal and fetal tissue are unique and species-specific.”
Experiments showed that nanoparticles present in placental tissue disrupt the production of a large amount of messenger substances. And it is these messengers that can trigger serious changes in embryonic development, such as alterations in the formation of blood vessels.
These effects can be visualized in laboratory models using chicken eggs. The blood vessels of the egg actually grow at an enormous speed and density to allow embryonic development. A dense network of fine blood vessels lines the inside of the eggshell. The situation is strikingly different in the eggs treated with the altered messenger substances from the placenta treated with nanoparticles: in the experiments, the blood vessel system was not as dense but rather coarse-meshed. “The nanoparticles apparently have an indirect effect on the child in the womb, inhibiting the formation of blood vessels through messenger substances,” says Tina Bürki.
Health consequences
Currently, researchers are investigating all the messenger substances released by a placenta treated with nanoparticles, the so-called secretome. Without being contaminated, the interaction of hormones, inflammatory mediators and signaling substances for the formation of organ systems resembles a perfectly tuned orchestra. It is already clear that the communication between the placenta and the fetus is altered by the presence of nanoparticles and damages the formation of blood vessels. However, initial results show that nervous system development does not appear to be affected. Future analyzes will show what other disorders nanoparticles can indirectly cause. “Given that the effects can have repercussions on the health of the pregnant woman and the development of her child, these findings should be taken into account in the risk assessment of nanomaterials,” says the researcher.
The clinical partner, the Cantonal Hospital of St. Gallen, is also interested. As Thomas Rduch, from the Women’s Clinic and also a clinical researcher at Empa, says: “A healthy placenta is of utmost importance for the development of the child. Therefore, a correct assessment of the risk of environmental contamination is crucial for pregnant women.” .
the placenta
The placenta is an organ that forms exclusively during pregnancy. It provides nutrients to the child in the womb and also serves as a filter for environmental influences. This so-called placental barrier offers the fetus a certain degree of protection against pathogens or harmful substances. However, some substances, such as environmental estrogens, can cross the placental barrier and are suspected of being associated with various diseases.
Nanoparticles
Nanoparticles are only a few millionths of a millimeter in size. Among them is, for example, titanium dioxide, which can be found in many foods, cosmetics and medicines. Silicon dioxide is found, for example, in paints and printing paper and is also used as a food additive. Other nanoparticles come from environmental pollution processes such as plastic abrasion (nanoplastics) or industrial soot. They can enter the human body through the respiratory tract, digestive tract or skin.