Cell contamination assay

A method for determining the presence and/or level of contamination by pluripotent stem cell (PSC) contaminants in a PSC-derived cell population for further use, the method comprising

• assaying a sample of the PSC-derived cell population against at least one pre-determined miRNAs known or determined to be differentially expressed in PSC contaminants, where one or a panel of miRNAs one or more miRNAs selected from a group consisting of:
• hsa-miR-302a-3p, hsa-miR-302b-3p, hsa-miR-302c-3p and, hsa-miR-302d-3p,
• wherein the step of assaying the sample of the PSC-derived cell population comprises:
• treating the sample to measure a level of the at least one pre-determined miRNAs by quantitative reverse transcriptase polymerase chain reaction (RT-PCR), digital PCR or droplet digital PCR;
• and
• determining therefrom the presence and/or level of contamination by PSC contaminants in the sample;
• wherein the PSC contaminants comprise one or more of undifferentiated PSCs and incompletely differentiated PSCs;
• and
• wherein the method is configured to determine whether the level of contamination by PSC contaminants meets the criterion of ten or fewer PSC contaminant cells per one million cells of the sample.