CCL2 and COVID-19: Furthermore, we investigated the influence of MSC-EVs on inflammation by measuring changes in mRNA expression levels of inflammatory markers associated with COVID-19 severity, including TNF-α, IL-1β, IL-6, CCL2, and CXCL10. SARS-CoV-2 infection strongly upregulated the mRNA expression of the aforementioned inflammatory cytokines and chemokines.