The interrelation between the high expression level of MIR34a and the trisomic abortion materials

The underlying mechanism and constitution of spontaneous abortions are complicated and heterogeneous. Many factors, including epigenetic scenarios like micro-ribonucleic acids (miRNAs, MIRs), can additively affect the progression of pregnancy losses. This study aimed to evaluate whether the expression levels of placental inhibitor and/or activator miRNAs had a difference between the numerically abnormal and normal karyotyped spontaneous abortions.

The case-control study included 100 spontaneous abortion materials consisting of trophoblastic tissues with 42 disomies (controls), 43 aneuploidies (including trisomy 16, 21, 22, and monosomy X), and 15 triploidies. Disomic abortion materials with XX normal karyotypes were omitted from the study to exclude possible maternal decidual cell contamination. Total RNA isolation was performed with TRIzol™ reagent directly from frozen trophoblastic tissues, and the mature miRNAs were obtained by reverse transcription via quantitative real-time polymerase chain reaction (qRT-PCR). Then, the expression levels of placental activators MIR378a-5p, MIR376c, MIR195, and inhibitors MIR34a and MIR210 were relatively evaluated using MIR130 as a reference.

The expression level of placental inhibitor MIR34a was detected to be high in trisomic abortion materials (trisomy 16 and 21) when compared to the disomic ones (p = 0.0324). MIR195 (p = 0.0484) and MIR34a (p = 0.0346) expression levels were increased in numerically abnormal cases with advanced maternal age compared to the disomic ones within all maternal ages.

It seems likely that the high expression level of MIR34a and the coexistence of trisomic abortion materials are quite interrelated with the additive effect of advanced maternal age.