Identification of novel cumulus cell molecular markers predictive of oocyte competence: confirmation with pregnancy outcome

Abstract

To identify molecular markers predictive of human embryo implantation. Prospective Cohort Cumulus cells from all retrieved oocytes (No = 49) of 6 IVF patients who were chosen in random were mechanically separated prior to fertilization and frozen in liquid nitrogen for future evaluation. We selected heat shock protein transcription factor (HSF1), mitochondrial transcription factor A (TFAM), endoplasmic reticulum oxidoreductin1(ERO1LA), peroxiredoxin6 (PRDX6), and enolase 1(eno1), as well as 2 housekeeping genes (GAPDH and 28S RNA) for this study. Quantitative real-time Polymerase chain reaction methodology using standard curve analysis was employed to quantify the relative gene expression level. Unpaired student's t-test was used for statistical analysis. A mean of 2 ± 1.2 embryos were transferred per patient. There were three clinical pregnancies (positive group), one biochemical and two negative pregnancies (negative group). As shown in the table, among the five markers tested, HSF1 and Enolase1 were found to be significantly over expressed only in the negative group.Tabled 1GroupGADPH28SRNATFAMPRDX6ERO1 LAHSF1Enolase 1Positive Mean ± SEM21.6 ± 10.855.8 ± 4.130.7 ± 0.2319.9 ± 12.53.2 ± 1.387.5 ± 4.5269.8 ± 35.35Negative Mean ± SEM70.1 ± 29.3120.2 ± 12.212.8 ± 1.3546.9 ± 17.4111.2 ± 5.0∗∗81.3 ± 38.2∗P=0.04; P=0.03283.5 ± 115.3∗ P=0.04; P=0.03 Open table in a new tab Because of limited information provided by morphological assessment of embryos, IVF programs choose to transfer several rather than a single embryo to increase the odds of pregnancy. The unfortunate consequence of this practice is higher multiple pregnancy rates. Our study demonstrates a significant down regulation in the expression of HSF1 and enolase 1 in the cumulus cells of the oocytes that resulted in pregnancy. We conclude that low cumulus expression of HSF1 (playing a role in environmental and pathophysiological stresses) and Enolase1 (an enzyme of the glycolytic energetic pathway) may prove useful in selection of embryos most suitable for transfer.