WT and engineered hPSCs were subcutaneously injected in immunodeficient mice and monitored for teratoma formation over the course of 4 to 6 weeks. WT teratomas displayed a slower increase in volume compared to engineered teratomas. Furthermore, histology staining and qPCR analysis of human effector T cell markers CD8 and IL-2 had demonstrated reduced T cell infiltration in engineered cell lines compared to WT. The gene discussed is CD8A; the disease is teratoma.