Construction of amniotic cell line with chromosomal abnormalities and its application in the quality control of chromosome karyotype analysis

The aim of this study was to investigate the application of amniotic fluid cell lines with chromosomal abnormalities in the external quality assessment (EQA) of prenatal karyotype analysis. Simian virus 40 large T antigen (SV40LT) gene was transfected into amniotic fluid cells with 46,XY,t(15;17)(q11;q11) and 46,XY by liposome transfection. Control cell lines were produced by mixing the above two in ratios of 1:19, 1:1 and 9:1, respectively. The cells were then frozen at −30 °C, mailed between laboratories, prepared for chromosome analysis, photographed with karyotype, and evaluated. After the two amniotic fluid cell lines and the control cell lines were serially passaged for 10 generations, they were still spindle-shaped with adherent growth. The 46,XY,t(15;17)(q11;q11) line preserved the original amniotic fluid karyotype, whereas a small number of cells with 46,XY, had changes of chromosomal structure. After mailing between laboratories, the abnormal karyotype was scored to constitute, 10.8%, 54.2% and 81.2% on average in the 1:19, 1:1 and 9:1 samples, respectively. There were significant differences (P < 0.05) between the actual scores and the theoretically expected ones with respect to the controls with 5% and 90% abnormal karyotype, whereas no significant difference (P > 0.05) with respect to the ratio of 50%. Overall, we demonstrated that the SV40LT gene could immortalize amniotic fluid cells with chromosomal abnormalities. The immortalized cells with and without chromosomal abnormalities mixtured in different ratios could then serve as control cells in the EQA of prenatal karyotype analysis.