AUTHOR=Wang Shihua H. , Shetty Ashok K. , Jin Kunlin , Chunhua Zhao Robert TITLE=Combating COVID-19 With Mesenchymal Stem/Stromal Cell Therapy: Promise and Challenges JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=8 YEAR=2021 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2020.627414 DOI=10.3389/fcell.2020.627414 ISSN=2296-634X