How Bioprinted Mini-Placentas Could Help Us Understand Pregnancy Complications

Placentas are a small but mighty organ, with many unique traits. It’s the only organ that is “disposable,” and a new one begins to form each time a fertilized egg is implanted in the uterus. Then, they grow rapidly in conjunction with the fetus, and can become the size of a small plate. This humble organ is literally a baby’s lifeline: babies don’t breathe or eat in the womb, so the placenta acts as their oxygen and nutrient supply, as well as the baby’s kidneys, which filter out waste from the bloodstream.

Although the placenta is critical to fetal development, it remains one of the least understood organs in human biology. One reason is that it is difficult to obtain samples during pregnancy without risking complications such as infection or miscarriage. After birth, the tissue changes significantly, making it unsuitable for studying early placental development. Animal models provide limited insight because most animal placentas differ substantially from those of humans. As a result, researchers still lack a clear understanding of how the placenta develops and functions, particularly in the early stages of pregnancy.

A placental organoid under the microscope

Placental Organoids

By 3D printing artificial mini-placentas, called organoids, researchers from the University of Technology Sydney are trying to fill this gap in understanding. Organoids, which arrived on the medical scene in 2009, are created by suspending stem cells in a gel that allows them to form clusters as they grow and divide. In 2018, researchers created the first placental organoids using trophoblasts, which are a cell type only found in the placenta.