Cells in human amniotic fluid used to build “mini organs”

Amniotic fluid contains cells, cells shed by the growing fetus and which could be used to build “mini organs” in vitro, as a new study reports ¹.

What do we mean by “mini organs”? This so-called organoids are 3D cellular systems that aim to replicate the structure and function of real organs but at a smaller scale. They are a simplified model of an organ. They are usually developed to perform research on disease and to test drugs in development in a more biologically relevant way.

Until now, organoids were either created from stem cells from terminated pregnancies or derived from biopsies, in which “adult” cells are de-differentiated to a progenitor cell-like state. The advantage of using naturally existing, flowing fetal cells in amniotic fluid is that it removes some of the ethical issues associated with the use of embryos for research.

The technique used to achieve growing these organs involved recovering lung, kidney, and intestinal cells from amniotic fluid collected from 12 pregnant women at 16–34th weeks of gestation. Once isolated, the cells were grown in vitro until they organized themselves into an organ-like structure. As expected, each organoid expressed the genes and proteins of the organ the isolated cells belonged to.

This is very interesting, not only for research purposes but also, as the researchers tested in their study, it can serve to follow up on the success of in utero interventions to heal disease before birth. As an example, they created lung organoids from fetuses with congenital diaphragmatic hernia (CDH), which means that the diaphragm cannot properly close during development, before and after treatment.

Their observation of the changes in organoid formation occurring after treatment gave insights into the effectiveness of the intervention. Although still under wraps, this is a very promising technique both for research into personalised medicine and drug development but also for the functional assessment of in utero treatment of congenital disease. Clearly, amniotic fluid extraction is an invasive technique with associated risks for the developing fetus, so this is not an approach to be extended to all pregnancies but, for those already at risk, this intervention might help in the future.