RNA-seq analysis for the transplanted MSCs in COVID-19 patients showed that the transplanted MSCs do not express ACE2 or TMPRSS2, indicating that MSCs cannot be infected with COVID-19; however, they express high levels of anti-inflammatory and paracrine factors, such as HGF, FGF, EGF, TGF-β, GAL, LIF, NOA1, VEGF, NGF, and BDNF. Here, BDNF is linked to COVID-19.