LAUSR

Previous studies reported safety and applicability of Mesenchymal Stem/Stromal Cells (MSC) to ameliorate pulmonary inflammation in ARDS. Thus, multiple clinical trials assessing the potential of MSC for COVID-19 treatment are underway. Yet, as SARS-inducing corona viruses infect stem/progenitor cells, it is unclear whether MSC could be infected by SARS-CoV-2 upon transplantation to COVID-19 patients. We found that MSC from bone marrow, amniotic fluid and adipose tissue carry angiotensin-converting enzyme 2 and transmembrane protease serine subtype 2 at low levels on the cell surface under steady state and inflammatory conditions. We did neither observe SARS-CoV-2 infection nor replication in MSC at steady state, under inflammatory conditions, or in direct contact with SARS-CoV-2 infected Caco-2 cells. Further, indoleamine 2,3-dioxygenase 1 production in MSC was not impaired in the presence of SARS-CoV-2. We show that MSC are resistant to SARS-CoV-2 infection and retain their immunomodulation potential supporting their potential applicability for COVID-19 treatment.