The SECRET is Installation Research Project (UIP-2019-04-2178) funded by Croatian Science Foundation aimed at conducting a comparative analysis of animal and human adipose-derived mesenchymal stem cells (AD-MSCs) peculiarities, changes in gene expression and secretome composition during cultivation, before and following viral infection. Although stem cells are mostly linked to regenerative medicine and experimental therapy, we believe that their extraordinary properties should be also exploited in the field of virology to reveal cellular behavior and viral struggle during infection course in vitro.