Since the COVID-19 outbreak was acknowledged by the WHO on January 30, 2020, much research has been conducted to unveil various features of the culprit SARS-CoV-2 virus. Different rates of contagion in adults, children, and pregnant women may guide us to the underlying infection conditions of COVID-19. Reviewing the recent reports of COVID-19 clinical outcomes in children and pregnant women, we can find that children and pregnant women demonstrate a lower rate of COVID-19 infection and milder symptoms (1, 2). The stem cell composition in children and pregnant women shows similarity in characteristics. The unique molecular signature, the very low expression of angiotensin-converting enzyme 2, and the lower ratio of ACE/ACE2 of stem cells in children and pregnant women compared to adults might be the cause of milder symptoms of COVID-19 in them. Stem cells in adults (including hematopoietic stem cells, muscle satellite cells, and MSCs) are mostly quiescent, in the G0 phase of the cell cycle, with a lower rate of proliferation and regenerative properties (3, 4), while children and pregnant women have active and fetal-derived stem cells circulating in their bodies, that are able to combat illnesses and repair the injured tissues (5). That’s why stem cells can function properly and exert their immunomodulatory and regenerative effects in the COVID-19 infected children and pregnant women while failing to replicate their role in adults. Perhaps making a treatment that could stimulate the adult stem cells and push them through the G1 phase of the cell cycle might exert both a preventive and regenerative effect in COVID-19 patients and provide a novel therapy for this pandemic.

Keywords: COVID-19, Stem cells, Sars-CoV-2, Pregnant women