Single‐cell RNA expression profiling of ACE2 and TMPRSS2 in the human trophectoderm and placenta

Cui, D.; Liu, Y.; Jiang, X.; Ding, C.; Poon, L. C.; Wang, H.; Yang, H.

OBJECTIVES: The objective of this study was to examine the characteristics and distributions of possible SARS‐CoV‐2 target cells in the human TE and placenta. METHODS: Single‐cell transcriptomic datasets of the early TE as well as the first‐ and second‐trimester placentas have been reported(1,2). Here, we conducted the transcriptomic analysis of 4198 early TE cells, 1260 first‐trimester placental cells and 189 EVTs at 24‐week placentas (EVT_24W) by SMART‐Seq2 method. Immunohistochemical staining of the human first‐, second‐ and third‐ trimester placentas was performed to confirm bioinformatic results. RESULTS: Via bioinformatic analysis, we identified the existence of ACE2 and TMPRSS2 expression in human TE as well as in the first‐ and second‐ trimester placentas. In human TE data, 54.4% of TE1 cells, 9.0% of CTBs, 3.2% of EVTs and 29.5% of STBs were ACE2 positive. As for TMPRSS2, 90.7% of TE1 cells, 31.5% of CTBs, 22.1% of EVTs and 70.8% of STBs were TMPRSS2 positive. Amongst the placental cells, 20.4% of CTBs, 44.1% of STBs, 3.4% of EVT_8W and 63% of EVT_24W were ACE2 positive. And 1.6% of CTBs, 26.5% of STBs, 1.9% of EVT_8W and 20.1% of EVT_24W were TMPRSS2 positive. Pathway analysis revealed associations to morphogenesis of branching structure, extracellular matrix interaction, oxygen binding and antioxidant activity in ACE2+TMPRSS2+ EVT_24W cells. The ACE2+TMPRSS2+ TE1 cells were correlated with an increased capacity of viral invasion, epithelial cell proliferation and cell adhesion. Based on immunohistochemical results, expression level of ACE2 and TMPRSS2 in first‐ and second‐ and third‐trimester placentas was observed. CONCLUSIONS: Our study has demonstrated the presence of ACE2 and TMPRSS2 positive cells in the human TE and placentas at different stages of pregnancy, which indicates the possibility that the SARS‐CoV‐2 could spread via the placenta and cause intrauterine fetal infection. This article is protected by copyright. All rights reserved.