Human Early Syncytiotrophoblasts Are Highly Susceptible to SARS-CoV-2 Infection (preprint)

The ongoing and devastating pandemic of coronavirus disease 2019 (COVID-19) has led to a global public health crisis. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and can potentially pose a serious risk to maternal and neonatal health. Cases of abnormal pregnancy and vertical transmission of SARS-CoV-2 from mother to foetus have been reported but no firm conclusions are drawn. Trophoblasts are the major constituents of the placenta to protect and nourish the developing foetus. However, direct in vivo investigation of trophoblast susceptibility to SARS-CoV-2 and of COVID-19 and pregnancy is challenging. Here we report that human early syncytiotrophoblasts (eSTBs) are highly susceptible to SARS-CoV-2 infection in an angiotensin-converting enzyme 2 (ACE2)-dependent manner. From human expanded potential stem cells (hEPSCs), we derived bona fide trophoblast stem cells (TSCs) that resembled those originated from the blastocyst and the placenta in generating functional syncytiotrophoblasts (STBs) and extravillus trophoblasts (EVTs) and in low expression of HLA-A/B and amniotic epithelial (AME) cell signature. The EPSC-TSCs and their derivative trophoblasts including trophoblast organoids could be infected by SARS-CoV-2. Remarkably, eSTBs were highly susceptible to SARS-CoV-2. They expressed high levels of ACE2 and produced substantially higher amounts of virion than Vero E6 cells which are widely used in SARS-CoV-2 research and vaccine production. These findings provide experimental evidence for the clinical observations that opportunistic SARS-CoV-2 infection during pregnancy can occur. At low concentrations, two well characterized antivirals, remdesivir and GC376, effectively eliminated infection of eSTBs by SARS-CoV-2 and middle east respiratory syndrome-related coronavirus (MERS-CoV), and rescued their developmental arrest caused by the virus infection. Several human cell lines have been used in coronavirus research. However, they suffer from genetic and/or innate immune defects and have some of the long-standing technical challenges such as cell transfection and genetic manipulation. In contrast, hEPSCs are normal human stem cells that are robust in culture, genetically stable and permit efficient gene-editing. They can produce and supply large amounts of physiologically relevant normal and genome-edited human cells such as eSTBs for isolation, propagation and production of coronaviruses for basic research, antiviral drug tests and safety evaluation.

Application of Remote Fetal Heart Rate Monitoring Based on Internet in Late Pregnancy During the COVID-19 Pandemic (preprint)

Objective：To evaluate the consistency of pregnancy outcomes and related clinical monitoring indicators in high and low risk group under two different monitoring methods during COVID-19 pandemic.Methods：760 cases of late pregnant women admitted to our hospital from March 2020 to February 2021 were selected for this study. They were randomly divided into control group (n = 380) and observation group (n = 380). Observation group the fetus was monitored remotely at home，while the control group went to the hospital for fetal heart monitoring.To evaluate the consistency of pregnancy outcomes and related clinical monitoring indicators in different groups under two different monitoring .Results:It was found that there was no statistically significant difference between the two groups in terms of pregnancy outcome (including mode of delivery, postpartum hemorrhage, etc.) and neonatal outcome (including preterm birth rate, neonatal weight, neonatal Apgar score, etc.) (p>0.05). It should also be noted that the difference in EPDS score results between the two groups was statistically significant (p<0.05) . Meanwhile, there was a statistically significant difference in the total cost of labor and delivery between two groups (p<0.05) and total time spent on labor and delivery between the two groups(p<0.05).Conclusions:Remote Fetal Heart Rate Monitoring Based on Internet is an innovative, acceptable, and effective reduced-frequency prenatal examination model. Compared to routine prenatal examination, Remote Fetal Heart Rate Monitoring Based on Internet resulted in higher patient satisfaction and lower prenatal stress. Besides, Remote Fetal Heart Rate Monitoring Based on Internet compared with the traditional fetal heart monitoring does not affect the pregnancy outcomes of pregnant women with different risk factors, maternal accept degree is high, and to reduce the medical resources pressure. It is an effective and feasible way for self-monitoring of pregnancies in late pregnancy during the pandemic of COVID-19 and is worthy of clinical application.