Recently, there have been reports that mesenchymal stem/stromal cells (MSCs) secrete immunomodulatory cytokines such as TGFBI (33), PGE2, and IL-6, which are expected to be promising therapeutic targets for both OA and critical COVID-19 (34), strongly supporting shared features in the etiological pathways leading to these two conditions. Here, IL6 is linked to COVID-19.