127 Metabolomics analysis of human cumulus cells from oocytes exhibiting different developmental competence

Abstract

Cumulus cells play fundamental metabolic roles during folliculogenesis, being closely connected to the oocyte through transzonal projections. These oocyte-supporting cells are removed and discarded before intracytoplasmic sperm injection (ICSI), thereby constituting an interesting biological material on which to perform molecular analyses aimed to predict oocyte developmental potential. The objective of this study was to determine the possible differences in the amount of biochemical compounds in human cumulus cells from oocytes exhibiting different developmental competence: (1) oocytes not developing to blastocyst following ICSI (Bl−), (2) oocytes developing to blastocyst but failing to establish pregnancy following embryo transfer (P−), and (3) oocytes developing to blastocyst able to establish a pregnancy (P+). Cumulus cells were removed following conventional chemical and mechanical treatments before ICSI. Following cell dissociation, cumulus cells from individual oocytes were pelleted by centrifugation at 1500 × g for 10 min, snap frozen in liquid nitrogen, and kept at −80°C until analysis. Once the developmental potential was known, metabolomics analysis was performed in 12 samples per group, each composed of cumulus cells attached to an individual oocyte. Metabolomics analyses were performed by Metabolon Inc., which provides unbiased metabolite analyses based on ultra-high-performance liquid chromatography-tandem mass spectroscopy (UPLC-MS/MS). Welch’s two-sample t-test was used to identify biochemicals that differed significantly between groups (P < 0.05). The analysis identified 97 compounds of known identity in human cumulus cells, excluding xenobiotics. Of these, only 3 showed significant differences between groups: (1) cysteine, more abundant (1.5-fold increase) in P− compared with Bl−; (2) erythronate, more abundant (1.25-fold increase) in P+ compared with Bl−; and (3) malonate, more abundant (1.55-fold increase) in Bl− compared with P−. No differences were found in other comparisons for these compounds, although tendencies (0.05 < P < 0.1) were noted for cysteine (1.68-fold increase in P+ vs. P−) and malonate (1.92-fold increase in P− vs. P+). These results suggest that metabolomics analysis of human cumulus cells provides a poor predictive value for the developmental potential of the enclosed oocyte.