P-291 Positive effects of inactivated blood serum in stabilizing the activity of antioxidants in embryo-free culture media

Abstract

Abstract Study question Does addition of blood serum to embryo culture media supplemented with antioxidants (AOXs) helps maintain the AOX activity under in vitro culture conditions? Summary answer The addition of inactivated blood serum (IBS) before AOX supplementation resulted in AOX activity stabilization in embryo-free culture media (EFCM) for up to 48 hours. What is known already Supra-physiological levels of reactive oxygen species (ROS) in embryo culture medium (ECM) can disturb embryo development possible due to oxidative stress. Hence, AOX supplementation of ECM has been used to counteract the potential negative effects of high ROS on gametes and embryos. However, rapid consumption of AOXs via interaction with ROS may reduce the AOX protection capacity particularly during extended culture conditions. The aim of this study is to investigate the efficacy of IBS in stabilizing the AOX activity of a combination of AOXs (EmbryORP®) when added to EFCM. Study design, size, duration In this prospective study, oxidation reduction potential (ORP) was assessed in EFCM by MiOXSYS System (UAB Caerus Biotechnologies, Vilnius, Lithuania). The ORP results reflect the overall balance between oxidants and antioxidants. ORP levels in follicular fluid obtained from dominant follicles of 40 oocyte donors were used as control. Participants/materials, setting, methods All dishes containing culture medium (GlobalTotal®, LifeGlobal®, Connecticut, US) were incubated for 48 hours in 8% CO2, 20% O2, 37 °C. Culture dishes were divided into four groups: Group A: EFCM without AOX, Group B: EFCM+AOX, Group C: EFCM+AOX+IBS, and Group D: EFCM+IBS. Levels of ORP were assessed in EFCM before AOX supplementation (0), immediately after adding AOX (1) and 48 hours following AOX supplementation (2). ORP results are expressed as millivolts (mV). Main results and the role of chance At 48 hours of culture, ORP value in group C (96.7 mV) was significantly lower than group A (345 mV; p = 0.00001), and was found to be similar to the physiological ORP values found in follicular fluid from donors (89 mV±23.6 mV; p > 0.05). Also, ORP value in group C (96.7 mV) was lower than group B (210 mV; p = 0.67) and group D (280.1 mV; p = 0.11). Limitations, reasons for caution This study only tested the efficacy of IBS as AOX stabilizer in EFCM over 48 hours. The efficacy and potential risks associated with the use of IBS during actual embryo culture were not examined. Wider implications of the findings The use of AOX stabilizers may represent an important novel finding to maintain sufficient AOX protective capacity during extended culture conditions. Trial registration number 10112021-AOX