To investigate the degree of permissivity of FM-MSCs to HSV-1 and HSV-2, monolayers of FM-MSCs were infected with a clinical isolate of HSV-1, or the HSV-2 laboratory strain G. When infected cells were observed under an optical inverted microscope, the typical HSV-induced cpe became apparent from 16–24 h pi at high moi (1A), whereas cpe was observable only at later times after infection at low moi. Here, CPE is linked to infection.