A Randomized, Double-Blind, Placebo-Controlled Clinical Trial to Determine the Safety and Efficacy of Hope Biosciences Allogeneic Mesenchymal Stem Cell Therapy (HB-adMSCs) to Provide Protection Against COVID-19  HB-adMSCs  100  3 groups of patients, will receive five IVs at 200, 100 and 50 million cells/dose  Phase 2  USA  58