Intervention
dyspnea
PCT
Before the administration of either MSCs or placebo, history-taking and physical examination [including the Modified Medical Research Council (mMRC) dyspnea scale], routine hematological testing, inflammatory marker testing [procalcitonin (PCT), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)], chest X-ray, respiratory testing [peripheral oxygen saturation (SpO