Rabbit Anti-Human GREM1 (a.a. 26-184) Polyclonal antibody

Research question: Does double stimulation (DuoStim) affect cumulus cell gene expression in luteal-phase-derived oocytes? Design: This prospective observational study included 39 patients with reduced ovarian reserve. Fifteen patients (group 1) underwent IVF with a gonadotrophin-releasing hormone antagonist in the follicular phase and 24 patients (group 2) underwent DuoStim. A total of 149 cumulus cell samples were divided into two groups according to the phase of the cycle: group 1 included 55 follicular-phase-derived oocytes and group 2 included 94 luteal-phase-derived oocytes. The expression levels of the following genes were assessed using quantitative polymerase chain reaction: HAS2, VCAN, ALCAM, PTGS2, GREM1, ITPKA, TRPM7, SDC4, CALM2, SPSB2, TP53I3, PGR and PFKP. Results: The expression of 10 out of 13 genes in cumulus cells was similar between DuoStim luteal-phase-derived oocytes and follicular-phase-derived oocytes. A significant increase in the mRNA levels of VCAN (15.542 +/- 6.8 versus 20.353 +/- 10.58; P = 0.001), SDC4 (1.016 +/- 0.65 versus 1.318 +/- 0.97; P = 0.013), and TP53I3 (0.185 +/- 0.09 versus 0.270 +/- 0.11; P = 1.19E-05) was observed in group 2. The number of oocytes collected (5.57 +/- 2.3 versus 5.7 +/- 2.7; P > 0.05) and the number of blastocysts were comparable between the groups (2.1 +/- 2.1 versus 2.7 +/- 2.2; P > 0.05). Conclusions: The DuoStim approach leads to changes in the follicular environment. It affects the expression levels of VCAN, SDC4, and TP53I3 in the cumulus cells of luteal-phase-derived oocytes. These results, however, did not correlate with oocyte maturation, embryo quality and pregnancy rate.

The close relationship between cumulus cell function and oocyte developmental competence indicates that analysis of cumulus gene expression is a potential non-invasive method to aid embryo selection and lVF outcome. Cumulus was isolated from 674 oocytes from 75 women undergoing ICSI and gene expression analysed by quantitative RT-PCR. Cumulus expression of cyclooxygenase 2 (PTGS2) was higher with mature oocytes, whereas brain-derived neurotrophic factor (BDNF) was lower when fertilisation was normal. Expression levels of gremlin (GREM1) and BDNF were weak positive and negative predictors of embryo quality respectively. Ranking of GREM1 expression within cohorts of oocytes showed that oocytes associated with the highest GREM1 expression were more likely to be transferred or cryopreserved than discarded (49 vs 33%, P<0.02), although the clinical pregnancy rate was not significantly different. This study demonstrates both the feasibility and difficulties of this method of analysis in the largest such group studied thus far. Novel relationships between BDNF expression and fertilisation were identified, and the potential value of GREM1 expression as a marker of embryo quality supports the further assessment of GREM1 analysis in the context of embryo selection. Reproduction (2009) 138 629-637