Identification of differentially expressed markers in human follicular cells associated with competent oocytes

The development of an accurate method for selection of high-quality embryos is essential to achieve high pregnancy rates with single embryo transfer in human IVF. The developmental competence of the oocyte is acquired during follicle maturation and strong communication also exists between the follicular cells (FCs) and the oocytes; thus oocyte developmental competence may be determined by markers expressed in the surrounding FCs. From consenting patients (n = 40), FCs were recovered on a per follicle basis by individual follicle puncture. Hybridization analyses using a custom-made complementary DNA microarray containing granulosa/cumulus expressed sequence tags (ESTs) from subtracted libraries and an Affymetrix GeneChip® were performed to identify specific genes expressed in follicles leading to a pregnancy. The selected candidate genes were validated by quantitative-PCR (Q-PCR). Subtractive libraries prepared from pooled samples representing pregnant versus non-pregnant patients produced 1694 ESTs. Hybridization data analysis discriminated 115 genes associated with competent follicles. Selected candidates were confirmed by Q-PCR: 3-beta-hydroxysteroid dehydrogenase 1 (P = 0.0078), Ferredoxin 1 (P = 0.0203), Serine (or cysteine) proteinase inhibitor clade E member 2 (P = 0.0499), Cytochrome P450 aromatase (P = 0.0359) and Cell division cycle 42 (P = 0.0396). Microarray technologies are useful to mine the transcriptome of FCs expressed in follicles associated with competent oocytes and could be used to improve embryo selection with the objective of successful single embryo transfer.