PDGFRB and COVID-19: However, we observed no transcription of the following serotonin-related genes in MSCs from the three groups of individuals: HTR1B and HTR2B (serotonin receptors), PDGFRB, and CPA3 (data not shown).Our results show the adaptability of MSCs to the pulmonary environment during the SARS-CoV-2 infection and justify the efforts to establish MSC-based therapies to treat acute COVID-19 and post COVID-19 sequelae.