engleski

Genes for Anti-Müllerian Hormone and Androgen Receptor are under-expressed in human cumulus cells surrounding morphologically highly graded oocytes

Study question: Can expression profiles of AMH gene and its respective receptors in cumulus cells be biological markers for the oocyte, zygote or embryo quality? Summary answer: Morphologically suboptimal oocytes had statistically significantly higher levels of AMH and AR gene expression in their associated cumulus cells. What is known already: Morphological assessment of the oocyte, commonly used during ART, is not always a good predictor of successful fertilization and the developmental capacity of the ensuing zygote. Identification of specific genes or other biological components of the microenvironment surrounding each oocyte such as cumulus cells (CCs), could potentially enable more accurate distinguishing between high and low quality oocytes. Previous studies have investigated AMH gene expression levels in CCs, along with its correlation with the oocyte quality, but the obtained results were inconsistent and contradictory. A few studies have found connection between gene expression of AR, AMH and FSHR in CCs. Study design, size, duration: Study design: cross sectional -morphologically highly (N=107) versus poorly (N=22) rated oocytes. Size: 129 CCs and 35 follicular fluid samples from 58 patients undergoing ART. Duration: one year. Sampling procedure: Each follicle from the patients included was aspirated separately and the cumulus-oocyte complex (COC) was isolated. CCs were removed from the oocyte, oocytes were cultivated separately. Follicular fluids were included in the study if the COC was identified. Participants/materials, setting, methods: Study included 129 CCs and 35 FF samples from 58 patients undergoing ICSI procedure. AMH, AMHR2, FSHR and AR gene expression levels were analysed on a real-time PCR device using TaqMan technology. Concentrations of AMH in FFs were measured by enzyme-linked immunosorbent assay. Morphological assessment of oocytes was conducted immediately before and during the ICSI procedure, Zygotes and embryos were assessed 16-18 hours and 64-66 hours after fertilization, respectively. Main results and the role of chance: The results yielded suggest a relationship between AMH, AR and oocyte morphology: AMH and AR gene expression levels in CCs surrounding morphologically optimal oocytes were significantly lower than in CCs surrounding oocytes with suboptimal morphology (2- ΔΔCt(AMH) = 1.703 ; p = 0.011 and 2- ΔΔCt(AR) = 1.530 ; p = 0.008 respectively). Statistically significant positive correlation was found between mRNA expression levels of AMH and FSHR (p < 0.001), AMH and AR (p = 0.001), AMHR2 and FSHR (p < 0.001), AMHR2 and AR (p < 0.001), as well as between FSHR and AR (p < 0.001). No significant differences were found in AMHR2 or FSHR mRNA expression levels among different morphological groups of oocytes, zygotes and embryos. The concentration of FF AMH did not differ significantly between different morphological groups of oocytes, zygotes and embryos (p = 0.082, p = 0.230 and p = 0.486, respectively). There are no correlations between FF AMH concentration and mRNA expression levels of the AMH, AMHR2, FSHR or AR genes in associated CCs (p = 0.195, p = 0.809, p = 0.461 and p = 0.240, respectively). Limitations, reasons for caution: Due to heterogeneity of the study population regarding age and controlled ovarian stimulation protocol it is possible that some of gene expression differences could be the result of individual patient’s characteristics and not of oocyte/zygote/embryo quality itself. Wider implications of the findings: Negative association between AMH and AR gene expression levels in CCs and morphological quality of the oocyte from the same COC was reported for the first time. Research reinforces the importance of the COC and communication between an oocyte and its microenvironment for oocyte development, embryo formation and successful fertilisation.

Anti-Müllerian hormone ; cumulus cells ; follicular fluid ; oocyte quality ; oocyte morphology

nije evidentirano