Das Kulturmedium als entscheidender Faktor für die Embryoqualität

Choosing the right culture media in artificial reproductive technology (ART) cycles is a constant challenge for embryologists and physicians. Recently, minimizing metabolic stress for the embryo to enhance pregnancy rates has been suggested. Research on the metabolism of mammalian preimplantation embryos revealed that higher concentrations of lactate might be responsible for disturbing embryo metabolism. Hence, this study aims to evaluate the utilization rates for embryos cultured in low lactate media.

This prospective study included women aged 18–41 undergoing intracytoplasmic sperm injection (ICSI) with ≥ six mature (MII) oocytes. Oocytes from each patient were split equally at the time of insemination into the two media types: standard G‑TL^TM (Vitrolife) and low lactate CSCM (Fujifilm) with mineral-oil (Gynemed) overlay and cultured in Embryoscope+ (Vitrolife). A total of 428 embryos were obtained. The utilization rates (embryo transfer or cryopreservation) of day 3 and day 5/6 embryos were analyzed.

The number of achieved fertilized oocytes was 211 in G‑TL^TM and 217 in CSCM. Overall, the utilization rate was 64.3% using CSCM media compared to 52% in the G‑TL^TM group (p < 0,008). Additionally, the utilization rate of day 5 embryos was 58.1% using CSCM versus 43.1% with G‑TL^TM (p < 0.007). Interestingly, age stratification (18–30, 31–35, 36–41) revealed higher total and day 5/6 utilization rates when using CSCM media in all age groups. In addition, a slight trend for higher pregnancy and live birth rates was observed for embryos cultured in CSCM media.

The data show a significantly improved blastocyst utilization rate with CSCM media. It is tempting to speculate that an excess concentration of lactate in culture media might negatively influence embryo metabolism. This could be of particular significance during blastocyst stage when embryo glucose consumption increases as well as lactate production, accumulating in the culture media.