Scientists create novel imaging technique to study placental development in pregnant mice

Ellen McNally (22 April 2024)

Researchers from Duke University have developed an innovative imaging technique to study placental development in mice. The approach aims to further understanding of placental dysfunction during pregnancy to help improve prenatal care.

The research published in the journal Science Advances details how scientists created an implantable window and used an imaging tool known as Ultrafast Functional Photoacoustic Microscopy (UFF-PAM) to monitor how the placenta develops and functions.

The placenta provides oxygen and nutrients to a developing fetus while also removing waste. However, little is known about the organ’s development and function as it is difficult to study with traditional tools due to its constant movement and position deep within the abdominal cavity.

However, this new approach developed by lead researchers of the study, Junjie Yao and Dr. Liping Feng, bypassed this issue by creating an implantable window that provides direct access to the placenta in pregnant mice.

Coupled with UFF-PAM, the team were able to capture highly detailed images of the blood flow and oxygen levels of the complex organ.

“UFF-PAM can achieve high imaging speed, so the images aren’t disrupted by breathing or the motions of the embryo or placenta,” said Yao when speaking on the benefits of the imaging platform.

“By using it with the implantable window, we can see how the placenta grows, how it recruits new blood vessels, how it feeds the fetus, and other drastic changes in both healthy and diseased states over the 20-day gestational period.”

The researchers found that during normal placental development, oxygen levels dropped slightly from day 7 to day 10, while both blood vessel diameter and density increased by more than 200%.

“The low-oxygen environment triggers the placenta to grow a lot of vessels to facilitate the exchange of nutrients, oxygen and waste products between the mother and the fast-developing fetus.”

The team also analysed how lifestyle factors like alcohol consumption can affect placental function by injecting ethanol into the abdominal cavity and then observing changes in the organ’s blood dynamics.

They discovered that while alcohol caused a small decrease in the total blood vessel density, there was a significant initial increase in oxygen levels in the placenta. This provides evidence that alcohol can affect placental development by altering its blood flow and oxygen metabolism.

They also analysed how infection can affect the placental blood flow leading to complications such as pregnancy loss, premature birth, and smaller babies.

Infection caused significantly fewer and smaller blood vessels in the mouse’s placenta. This was accompanied by higher oxygen levels, meaning the placenta wasn’t triggered to make more blood vessels by being depleted of oxygen. This suggests that infection reduces placental blood flow, with the baby receiving insufficient nutrients required for growth.

Now that the team have proven the success of the technique, they aim to study more specific conditions and how they affect the placenta in the future. Feng says that “these tools not only help us to understand how pregnancy complications happen but also provide a pre-clinical tool for drug screening.”