Previous studies reported on the safety and applicability of mesenchymal stem/stromal cells (MSCs) to ameliorate pulmonary inflammation in acute respiratory distress syndrome (ARDS). Thus, multiple clinical trials assessing the potential of MSCs for COVID-19 treatment are underway. Yet, as SARS-inducing coronaviruses infect stem/progenitor cells, it is unclear whether MSCs could be infected by SARS-CoV-2 upon transplantation to COVID-19 patients. We found that MSCs 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 not observe SARS-CoV-2 infection or replication in MSCs 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 MSCs was not impaired in the presence of SARS-CoV-2. We show that MSCs are resistant to SARS-CoV-2 infection and retain their immunomodulation potential, supporting their potential applicability for COVID-19 treatment.

先前的研究报道了间充质干/基质细胞（MSC）改善急性呼吸窘迫综合征（ARDS）的肺部炎症的安全性和适用性。因此，正在进行评估MSCs用于COVID-19治疗的潜力的多项临床试验。然而，由于诱导SARS的冠状病毒感染干细胞/祖细胞，因此尚不清楚在移植至COVID-19患者后，MSC是否可以被SARS-CoV-2感染。我们发现，在稳态和炎性条件下，来自骨髓，羊水和脂肪组织的MSC在细胞表面上携带的血管紧张素转换酶2和跨膜蛋白酶丝氨酸亚型2含量较低。我们没有观察到SARS-CoV-2在炎性条件下处于稳定状态或在与SARS-CoV-2感染的Caco-2细胞直接接触的情况下在MSC中感染或复制。此外，在SARS-CoV-2的存在下，MSC中吲哚胺2，3-二加氧酶1的产生没有受到损害。我们显示，MSC对SARS-CoV-2感染具有抵抗力，并保留了其免疫调节潜能，从而支持了其对COVID-19治疗的潜在适用性。