Are Early Embryo Cleavage Kinetics Affected by Energy Substrates in Different Culture Media?

This study aimed to investigate the influence of different culture media on early embryonic cleavage kinetics using time-lapse analysis and to determine the possible relationships between energy substrates in culture media and the cleavage kinetics.

A total of 10 021 embryos from 1310 couples were cultured in time-lapse incubators. Embryos cultured in Vitrolife media were allocated to group I, and those in COOK media to group II. Embryo cleavage time points up to the 8-cell stage (t2-t8) were observed after pronuclei fading.

The baseline demographic features, in vitro fertilization indications, ovarian stimulation protocol, oocyte-cumulus complexes, fertilization rate, together with pregnancy and perinatal outcomes were similar (P>0.05) between groups I and II. According to the time-lapse analysis, all embryos in group I showed significantly faster cleavage speed than those in group II (P<0.05). Furthermore, there was better synchrony in division (s3) and a longer length of the third cell cycle duration (cc3) in group II. Interestingly, implanted embryos in group II showed faster cleavage speed than those in group I, especially at t4 and t7. The glucose contents and multiple major amino acids were similar between the two groups. Lactic and pyruvic acid contents were generally higher in group I than those in group II.

Because different commercial culture media may influence cleavage kinetics of embryos, it is essential for embryologists to take culture media into consideration in selecting a potential embryo when using a time-lapse system before implantation.