Interfering Effects of In Vitro Fertilization and Vitrification on Expression of Gtl2 and Dlk1 in Mouse Blastocysts

BACKGROUND: Embryo vitrification is a key instrument in assisted reproductive technologies (ARTs). However, there is increasing concern that vitrification adversely affects embryo development. This study intends to assess the effect of vitrification on developmental competence, in addition to expressions of long non-coding RNA (lncRNA) gene trap locus 2 (Gtl2) and its reciprocal imprinted gene delta-like homolog 1 (Dlk1), in mouse blastocysts. MATERIALS AND METHODS: In this experimental study, we have designed three experimental groups: control (fresh blas- tocysts collected from superovulated mice), in vitro fertilization (IVF; blastocysts derived from IVF) and vitrification (IVF derived blastocysts subjected to vitrification/warming at the 2-cell stage). Quantitative reverse transcription pol- ymerase chain reaction (qRT-PCR) was performed to assess the expression levels of Gtl2 and Dlk1 in the blastocysts. RESULTS: The results showed that vitrification group had significantly lower blastocyst and hatching rates compared to the IVF group (P<0.037) and (P<0.041), respectively. Gtl2 was down-regulated and Dlk1 was up-regulated following the IVF and vitrification (P<0.05). CONCLUSION: These results suggested that IVF and vitrification disturbed genomic imprinting and lncRNA gene expres- sions, which might affect the health of IVF children.