Expression of SARS-CoV-2 entry genes ACE2 and TMPRSS2 at single cell resolution in the peripartum decidua

Angiotensin-converting enzyme 2 (ACE2) is the key receptor for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). However, the susceptibility of the decidua to infection during the peripartum period has not been explored, even though this may affect vertical transmission. The objective of this study was to investigate the expression of ACE2 and related genes in the decidua during delivery. Here, single-cell RNA sequencing was used to characterize the transcriptomes of decidual cells before and after the onset of labor. During the peripartum period, ACE2 expression was highly heterogeneous. ACE2 was expressed principally in decidual stromal cells, uterine smooth muscle cells, and extravillous trophoblasts. Comparison of the transcriptomes of ACE2-positive and ACE2-negative cells indicated that ACE2-positive cells exhibited integrin clusters on the cell surface interactions. ACE2-positive cells were compared before and after labor onset. After delivery, the number of ACE2-positive cells was slightly higher than before delivery. Before labor onset, ACE2-positive decidual stromal cells were in the regulation of membrane protein ectodomain proteolysis cluster. After labor onset, the upregulated genes changed to include cell junction assembly genes. The susceptibility of decidual cells to SARS-CoV-2 infection is thus heterogeneous during the peripartum period.