Gene expression profiling of human blastocysts from in vivo and ‘rescue IVM’ with or without melatonin treatment

To evaluate the effect of melatonin supplementation in maturation medium for human 'rescue IVM' and investigate differences in transcriptomic profile of blastocysts developed from oocytes matured in vitro with/without melatonin treatment and in vivo, a total of 314 GV oocytes and 320 MI oocytes were collected from 200 patients younger than 35 years old undergoing ICSI cycle. The oocytes were randomly distributed in the control group (no melatonin) and four other groups of varying melatonin concentrations (10‑11, 10‑9, 10‑7, 10‑5 mol/l). Gene profiling was performed on blastocysts developed from in vivo maturation oocytes (in vivo group), and in vitro maturation (IVM) oocytes with an optimal concentration of melatonin treatment (IVM‑anti group) or without melatonin (IVM group). The ratio of high quality blastocysts was significantly higher in the groups treated with 10‑5 mol/l melatonin compared with others groups. The large‑scale analysis of the transcriptome revealed significant differences in mRNA expression levels. In each group, nine blastocysts were selected for gene expression profiling. The differentially expressed genes were involved in cysteine and methionine metabolism, regulation of apoptotic process, mineral absorption, steroid hormone biosynthesis, Wnt signaling, p53 signaling pathway and other functions. The findings indicated that the IVM procedure may potentially affect DNA methylation and the canonical Wnt signaling pathway. Exogenous melatonin positively influenced quality of blastocysts, which may be mediated via upregulation of p53 signaling and correcting DNA methylation changes caused by 'rescue IVM'. However, this study reflected what was generally referred to as 'rescue IVM' and was not a true reflection of clinical IVM techniques. Therefore, melatonin required further investigation as a promising supplement for use in IVM.