Amnion-on-a-chip: modeling human amniotic development in mid-gestation from pluripotent stem cells.

The amnion serves to create a protective environment for a growing fetus, and the study of amniotic development will greatly facilitate our understanding of normal and abnormal pregnancies. However, this remains a poorly studied field due to the lack of ideal human models. Herein, we present an integrative strategy to generate amnion-like cavity tissue from human pluripotent stem cells (hPSCs) in an amnion-on-a-chip device through combining a bioengineering approach and developmental biology principles. hPSCs could self-organize into an amnion epithelial cavity in a perfusable 3D culture microchip, resembling human amniotic development in mid-gestation. These cavities exhibited the critical features of amnion tissue based on morphological characteristics, marker expression, and transcriptome analysis. RNA-seq revealed that a set of amnion-specific genes were highly expressed in the obtained cavities, suggesting that the amnion epithelium was derived from hPSCs. Moreover, the amnion-specific mid-gestation marker KRT24 was highly expressed at the mRNA and protein levels, verifying the high maturation of amnion tissues after long-term 3D culturing and differentiation for up to 20 days. These new findings demonstrate the potential of this new amnion-on-a-chip model for investigating essential biological events in human amnions in normal and diseased states via integrating microengineering technology and stem cell biology.