Toward standardized iPSC testing: Insights from a multi-year international Quality Assessment Round

Despite rapid clinical translation, induced pluripotent stem cell (iPSC)-derived therapies face limited global adoption. Harmonized quality control (QC) remains absent, with even fundamental parameters evaluated inconsistently across laboratories. To address this, we conducted two international Quality Assessment Rounds (QARs): QAR 2019 (18 sites, 11 countries) and QAR 2023 (23 sites, 12 countries), evaluating flow cytometry-based assessment of the undifferentiated state and qPCR-based genomic integrity testing. QAR 2019 showed high consistency in genomic integrity testing, while uncovering substantial variability in flow cytometry, prompting QAR 2023 to introduce standardized workflows. These improvements enabled systematic, cross-site evaluation of marker performance across cell states, identifying OCT3/4, TRA-1-60, and SSEA5 as consistently robust pluripotency-associated markers. This global benchmarking effort provides the first empirical multi-site evidence for reproducible iPSC QC and marker-level reliability. Together, these findings establish a foundation for harmonized QC supporting interoperable iPSC banks, regulatory alignment, and scalable manufacturing of globally accessible regenerative therapies.