ZFN-mediated elimination of HLA-A expression on human ESC. The HLA-A2⁺HLA-24⁺hES parental cell line WIBR3 was modified by ZFN and donor plasmid coding for antibiotic resistance. Clones (5230, 5255, 5258) were chosen with loss of HLA-A expression and differentiated into fibroblasts. Expression of HLA-A2 and HLA-A24 on derived fibroblasts was assessed by flow cytometry after culturing with 600 IU/mL IFN-γ and 10 ng/mL TNF-α for 48 hours. Dashed line in parental panel represents isotype control.