Lecturer (Assistant Professor) University College London (UCL) London, England, United Kingdom
Abstract: The Amniotic Fluid (AF) surrounds and protects the human fetus during gestation. Highly heterogeneous, the AF is rich in primary fetal cells shed from multiple developing fetal tissues as well as fetal membranes and immune system. Despite this, the precise AF cellular composition remains largely unexplored. Here we applied single-cell technologies (i.e. scRNAseq) to over 150,000 uncultured AF cells from 30 AF samples (15-39GA) to generate a comprehensive single-cell atlas of the human AF. The epithelial cluster compose 60-70% of all AF cell identities. Through our work we provided initial annotation of every epithelial tissue contributing to the AF, as well as for each immune cell cluster. The analysis presented here, confirms that AF contains fetal epithelial populations from numerous fetal tissues. This includes specialised cells and progenitors from the fetal lung, kidney, gastrointestinal tract, some of which were capable of forming AF-derived Organoids (AFO). Moreover, progressing to a more comprehensive AF mapping, we annotated the multiple immune cell clusters present in the AF, in order to highlight what identities are consistently present in the AF at each single developmental time. Overall, this work allowed us to track the changes occurring in the AF cell composition along with the progression of fetal and organ development. Finally, to investigate the translational potential of AF single-cell mapping, we generated atlases from the fluids of pregnancies affected by Congenital Diaphragmatic Hernia (CDH, n=8 27-34GA) and myelomeningocele (Spina Bifida; SB n=5 23-25GA). When comparing these samples with our GA-matched reference AF atlas we observed variations in both cell cluster ratio and overall cellular composition. Interestingly we observed the appearance of disease-related AF cell clusters not detected in our reference data. We are currently reviewing the clinical files of the patients who donated the CDH/SB AFs, to investigate possible correlations between clinical outcomes and AF-cell composition. Overall, this work advances our knowledge on the biology of the AF, and its use to study congenital disease. Once completed, this will open the door to the translational use of AF mapping and, in combination with AFO, pave the way for advanced diagnostics and personalised disease modelling.
Funding Source: This work was supported by the Academy of Medical Science, UCL Therapeutic Acceleration Support, GOSH-CC, Kidney Research UK, CDH-UK, NIHR GOSH BRC and Rosetrees Trust. GD is supported by an EMBO Scientific Exchange Grant.
