The creation of stable, long-term, human placenta organoids is described in a paper published online in Nature this week. These organoid models represent a significant innovation for the study of human placental development.

Many disorders of pregnancy such as pre-eclampsia, fetal growth restriction, and stillbirth have their origin in abnormal placental growth in the first trimester. However, knowledge of the human placenta is limited owing to the lack of functional models on which to experiment. One strategy to resolve this issue is to develop an organoid, a miniaturized and simplified model of an organ grown in culture in a laboratory.

Ashley Moffett and colleagues describe the generation of long-term, genetically stable organoid cultures of specialist trophoblast cells derived from first trimester human placentas (6-9 weeks gestation). The cultures grew rapidly and developed three-dimensional organoid structures after 10-14 days. Three randomly selected cultures were still growing healthily after one year.

The organoids closely resemble physiologically-normal first trimester placentas, and display typical placental features such as differentiation into specific types of trophoblast cells, development of villous-like (finger-like) structures, and secretion of placental-specific hormones. This includes human chorionic gonadotropin (hCG) hormone, which is produced by the placenta after the implantation of the embryo to the uterine wall. These ‘pregnant’ hormone secretions could be detected by an over-the-counter pregnancy test. These organoids can be used to study the physiological, metabolic and hormonal changes that occur during pregnancy.