Increased somatic polyploidization in chorion of arrested pregnancies conceived through assisted reproductive technologies

BACKGROUND: The search for markers of disorders leading to miscarriage with normal embryonic karyotype is an important clinical and diagnostic problem, especially in pregnancies conceived with assisted reproductive technologies. AIM: Analysis of chorionic cells ploidy in naturally and assisted reproductive technologies conceived pregnancies. MATERIALS AND METHODS: A total of 52 chorion samples were included in the study. The samples were divided into groups depending on the developmental status of pregnancy (progressing/arrested), the way of conception (natural/assisted reproductive technologies) and karyotype (normal/trisomy 16). The ploidy of chorionic cells was studied using fluorescence in situ hybridization on interphase nuclei preparations. A total of 50,657 interphase nuclei were analyzed. RESULTS: Along with predominant diploid cells, polyploid cells were detected in all chorionic samples. Their frequency varied among samples from 0.1 to 8.22%. Polyploid cells comprised mainly tetraploid cells which were detected in all samples; triploid cells were also detected in 45 samples, and octoploid cells — in 5 samples. The highest total frequency of all polyploid cell types was found in chorion from assisted reproductive technologies-conceived arrested pregnancies, and the lowest — in chorion from progressing pregnancies. Frequency of tetraploid cells demonstrated the same pattern. Frequency of triploid cells was not associated with a developmental status of pregnancy and the way of conception. However, in chorion samples with trisomy on chromosome 16 in naturally conceived arrested pregnancies, a tendency towards a decrease in the frequency of triploid cells was noted. CONCLUSIONS: An elevated frequency of polyploid cells in chorion may indicate placentation abnormalities, leading to miscarriage even in the absence of embryonic karyotype anomalies. Therefore, an increase in somatic polyploidization in chorion may be considered a promising diagnostic marker of disorders in the placenta formation and functioning.