Oocyte - Cumulus Quality and cooculture : Benefit for implantation

1. Oocyte-CumulusQualityandcooculture: Benefitforimplantation Dr Moncef Benkhalifa, Ph.D. RBMG. Reproductive Biology & Genetics Technical & DevelopmentDirector Eylau Laboratory. UNILABS PARIS-GENEVA

2. In repeated implantation failure co-culture of human embryos with somatic cells has been reported to promote the improvement of embryos quality, implantation and pregnancy rate. It was reported also that feeder cells can be more beneficial to the oocyte and embryo by detoxifying the culture media and supporting the embryo development via different pathways.

4. Factors affecting oocyte competency

5. In vivo vs in vitro Culture conditions In vivoIn vitro Constant body temperature Thermal shocks Darkness Variations in light Controlled O2/CO2 Variations Volume of fluid Medium volume Dynamic changes in secretions Static/semi Static Free radical scavengers+/- (continuous control)

6. Gayan et al 2008

8. Fertil Steril March 2010

10. Conclusion: The Human Oocyte is able to regulate its Homocystein level via remethylation using MTR and BHMT but not CBS This aspect is importnat because recent studies have shown that controlled ovarian hyperstimulation affect the homocysteincon centration in follicular fluid This may regulate at least in part the risk of imprinting problems during IVF

11. At early embryo development, before genomic activation, there is no transcriptional activity. After maturation, the oocyte should contain all proteins and/or transcripts coding for all the enzymes required for the metabolic pathway. The gene activation of the first cell cycle of the early embryo is the longest during preimplantation development, any delay on this cycle will result in a decrease of the level of mRNA below critical thresholds Growth factors are potential candidates for embryo autocrine effects, however it is not obvious that growth factors can work through an internal loop, even if the genes for the ligands and the growth factors are expressed (Watson et al., 1992).

12. Co-culture of human embryos with somatic cells has been reported to promote the improvement of embryos quality, implantation and pregnancy rates after transfer (Spandorfer et al 2004, Kattal et al 2008, Eyheremendy et al 2009). The use of cumulus cell co culture has some advantages, they are easily obtained via the oocyte retrieval procedure during the IVF cycle and don’t need very sophisticated and maintenance culture. Besides, they are also autologous (Omar et Vlad 2008, Johnson et al 2009, Goovaerts et al 2009). EMBRYO CO-CULTURE

13. FERTIL STERIL October 2008

14. Fertil Steril 2006

19. confluent cumulus cells In situ hybridisation of LIF probe RT PCR product of PAF Receptor after 3 days culture It was reported that LIF improves in-vitro development of ovine (Fry et al., 1992) and bovine embryos (Fukui et al., 1994). PAF and VEGF both stimulate the tyrosine phosphorylation of a number of proteins, including focal adhesion kinase which raises the possibility that PAF directly or via VEGF may regulate endometrium cell motility and adhesion (Ahmed et al 1998 In the literature many authors reported that many cytokines and paracrine factors are produced by the embryo, the cumulus cells and the endometrium and participate to oocyte competency and embryo quality ( Ahmed et al 1998, Parik et 2006, Lin et al 2009, Godard et al 2009).

20. How can we explained Many any authors reported that many cytokines and paracrine factors are produced by the embryo, the cumulus cells and the endometrium and participate to oocyte competency and embryo quality One of the major contributions of these different factors can be the participation to embryo growth, cumulus cell competency improvement to support embryo blastulation and endometrium preparation for implantation. It was reported also that PAF and VEGF both stimulate the tyrosine phosphorylation of a number of proteins, including focal adhesion kinase which raises the possibility that PAF directly or via VEGF may regulate endometrium cell motility and adhesion .

21. Conclusion Embryo co-culture system with autologous cells can be beneficial in routine IVF for embryo selection and implantation improvement. More molecular investigations need to be done to elucidate better the complex dialogue between the embryo and feeder cells and the different involved biological pathways.

22. P Cohen Bacrie S Belloc N Prisant Martine Dumont Martine Cohen Bacrie Anne Marie Junca Yves Menezo Alain Dalleac Laboratoire D’Eylau. Paris UNLABS. Geneva Pr T Gurgan Dr A Demirol & Embryology team Women’s Health CLINIC. IVF & Genetics Dept . Ankara