Gene changes caused by plastics during in vitro fertilisation

Researchers found that placental gene expression is significantly altered in mice after IVF. Could it be due to the plastics used in the procedure?

The study investigates plastics' influence on gene expression in fetal organs

• Three groups of blastocysts were used for the study.
• Two of them were obtained by in vitro fertilisation (IVF), one of them in plastic material, the other in glass dishes. A third group was obtained by natural mating.
• At day 3.5 post fertilisation, the blastocysts were transferred to stimulated mother mice.
• On day 16.5 of gestation, the fetal organs were harvested and subjected to gene expression analysis. RNA was extracted from placenta and brain samples.
• RT-PCR was used to determine the fetal sex.

Due to the massive pollution of oceans and the debate about the effects of microplastics on humans and animals, an awareness of the problems in dealing with plastics has developed in recent years. However, the fact that the use of plastic materials can already be problematic at the beginning of life has hardly been taken into account.

Why could the use of plastic be dangerous?

In their study, Kouakou and his colleagues came to the following conclusions: In the placental genome, they found more than 1,000 deregulated genes after in vitro fertilisation in plastic dishes, while there were only 200 in embryos grown in glass materials, which is roughly equivalent to in vivo conception. This means that 5.6 times as many genes were altered in the placenta of the "plastic embryos" compared to under natural conditions.

Closer analysis also revealed that certain genes were overrepresented in the plastic-shell embryos, namely those associated with stress responses such as hypoxia and inflammation. It was also striking that the changes were greater in female placentas than in male placentas. In the brain, on the other hand, the researchers could not detect any relevant genetic dysregulations.

What are the risks of ART?

For more than 40 years, children have been born with the help of assisted reproduction technology (ART). It is now known: Their risk of low birth weight and other birth defects is greater than in the general population. Maternal risks such as haemorrhage, pre-eclampsia, and HELLP syndrome are also higher after artificial insemination. Finally, ART is associated with certain genetic syndromes such as Beckwith-Wiedemann syndrome. 

According to the French researchers, the plastic used during in vitro fertilisation could be one reason for this. The changes in the placental gene expression profile in particular could reduce the functional capacity of the placenta and disrupt maternal-fetal exchange. This could explain placental diseases such as pre-eclampsia as well as the often-low birth weight of children born from ART.

Significance for mothers and their children

The study suggests for the first time - albeit purely experimentally on the mouse model - a connection between assisted reproduction, the materials used in it, and the outcome on offspring. There are indications that plastics could lead to significant gene changes. Kouakou and his team therefore advocate for the exclusive use of glassware in ART.