Treatment of COVID-19 Pneumonia: the Case for Placenta-derived Cell Therapy.

Nearly 500'000 fatalities due to COVID-19 have been reported globally and the death toll is still rising. Most deaths are due to acute respiratory distress syndrome (ARDS), as a result of an excessive immune response and a cytokine storm elicited by severe SARS-CoV-2 lung infection, rather than by a direct cytopathic effect of the virus. In the most severe forms of the disease therapies should aim primarily at dampening the uncontrolled inflammatory/immune response responsible for most fatalities. Pharmacological agents - antiviral and anti-inflammatory molecules - have not been able so far to achieve compelling results for the control of severe COVID-19 pneumonia. Cells derived from the placenta and/or fetal membranes, in particular amniotic epithelial cells (AEC) and decidual stromal cells (DSC), have established, well-characterized, potent anti-inflammatory and immune-modulatory properties that make them attractive candidates for a cell-based therapy of COVID19 pneumonia. Placenta-derived cells are easy to procure from a perennial source and pose minimal ethical issues for their utilization. In view of the existing clinical evidence for the innocuousness and efficiency of systemic administration of DSCs or AECs in similar conditions, we advocate for the initiation of clinical trials using this strategy in the treatment of severe COVID-19 disease.