The severity of COVID-19 may be due in part to the patient’s response to the infection. To combat this cytokine storm, over 20 clinical trials aiming to treat COVID-19 with Mesenchymal stromal cell (MSC) therapies have been registered with ClinicalTrials.gov. Leng et al. conducted a pilot study of MSC transplantation in 10 patients in China. All tested positive for SARS-CoV-2 by polymerase chain reaction and had fever, shortness of breath, cough, and oxygen saturation at rest <95%. All seven MSC treated patients experienced resolution of symptoms while one of the three placebo-treated patients went on to develop ARDS and another died. Analysis revealed that MSC treatment, but not placebo, was associated with a halt in the increase of TNF–α and an increase in anti-inflammatory IL-10 concentrations, also C-reactive protein levels dropped 10-fold, suggesting a drop in systemic inflammation. This study provide safety data and efficacy that have motivated further exploration of MSCs as a treatment for COVID-19.