PhD Candidate Utrecht University Utrecht, Utrecht, Netherlands
Abstract: Human pluripotent stem cells (hPSCs) tend to acquire genetic aberrations upon culture in vitro. Common aberrations are mutations in the tumor suppressor TP53, suspected to confer a growth-advantage to the mutant cells. However, their full impact in the development of malignant features and safety of hPSCs for downstream applications is yet to be elucidated. Here, TP53 is knocked out in representatives of both an embryonic (H9) and an induced pluripotent stem cell line (LU07) using CRISPR-Cas9 technology. These were compared with their isogenic wild-type counterparts, as well as with malignant human germ cell tumor lines (2102EP, NCCIT) used as models of malignancy. While no major changes in proliferation, pluripotency, and transcriptomic profiles are found, mutant lines display aberrations in some of the main chromosomal hotspots for genetic abnormalities in hPSCs. Additionally, enhanced clonogenic and anchorage-free growth, alongside resistance to chemotherapeutic compounds is observed. The results indicate that TP53-depleting mutations in hPSCs, although commonly occurring and potentially overlooked by standard analyses, can impact their behavior by inducing a greater resilience to stressors, causing malignancy-associated traits hampering their safety in a clinical setting.
