X chromosome inactivation in human embryos obtained after either IVF or IVF/ICSI

There is concern that in-vitro culture of embryos and/or the ICSI technique might have an adverse effect on embryonic development via epigenetic alterations. In a previous study from our group using blastocysts resulting from surplus embryos obtained after either standard IVF or IVF/ICSI we found a clear sex related growth difference in human blastocysts originating from IVF/ICSI, but not in blastocysts originating from standard IVF. It is as yet unknown which mechanism is responsible for our findings. In in vitro produced female bovine blastocysts it has been shown that both X chromosomes were active while dosage compensation by X-chromosome inactivation did occur in in vivo generated embryos. Therefore, we hypothesize 1) that the process of X-inactivation has a time pattern in human preimplantation embryos comparable with that of the already investigated animal species, and 2) that the ICSI procedure might interfere with the process of X-inactivation in human embryos.

The ICSI procedure interferes with the process of X chromosome inactivation in human embryos

Human surplus embryos at several stages of development (ranging between 8-cell and blastocyst stage) will be collected and analysed for the X chromosome inactivation status.

The intervention on the embryos is intracytoplasmic sperm injection (ICSI), which is compared with conventional IVF. ICSI is a regular intervention used in case of male subfertility, where one spermatozoon is injected into an oocyte, while in IVF the spermatozoa and the oocyte are brought together within a culture dish.