Influence of global sperm DNA methylation on IVF results.
BACKGROUND
In cases of male infertility, routine analysis for sperm characteristics is a poor predictive factor for the segmentation rate and embryo development in assisted reproductive technologies. It is assumed that epigenetic factors could have an influence on the embryo's quality. The aim of this work was to determine the relationship between sperm DNA methylation level and fertilization and pregnancy rates according to the assisted reproduction technique performed.


METHODS
A prospective study was undertaken. Ejaculates were obtained from men (n = 63) undergoing an assisted reproduction procedure. 5-Methylcytosine was immunostained with a polyclonal antibody and revealed by fluorescein isothiocyanate. The DNA methylation level was then quantified by flow cytometry.


RESULTS
Sixty-three conventional IVF cycles were performed, 760 oocytes were retrieved, an average of 8.1 +/- 4.8 embryos was obtained, and 2.4 embryos were transferred. Neither the fertilization rate nor the rate of good quality embryos was correlated with the DNA methylation level (r = -0.1 and r = -0.08 respectively; not significant). When sperm DNA methylation was >555 arbitrary units, the pregnancy rate was 33.3% compared with 8.3% in the lower (<555) group (P<0.05).


CONCLUSIONS
DNA methylation level in human sperm could represent a new approach to study the ability of sperm to lead to pregnancy in an assisted reproduction procedure, especially when sperm samples with normal characteristics are used.
Benchaib
M
M
Département de Médecine de la Reproduction, Hôpital Edouard Herriot, place d'Arsonval, 69373 Lyon cedex 08, France. mehdi.benchaib@sante.univ-lyon1.fr
Braun
V
V
Ressnikof
D
D
Lornage
J
J
Durand
P
P
Niveleau
A
A
Guérin
J F
JF
D044503:5-Methylcytosine / Q000378:metabolism; D019175:DNA Methylation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000502:physiology; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006801:Humans; D007158:Immunologic Techniques; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology*; D013194:Staining and Labeling; D016896:Treatment Outcome
D005456:Fluorescent Dyes; D044503:5-Methylcytosine; D016650:Fluorescein-5-isothiocyanate