THE ADDITION OF ANTIOXIDANTS EVERY 12 HOUR TO THE CULTURE MEDIUM SIGNIFICANTLY INCREASES THE RATES OF TOTAL USABLE AND EXPANDED BLASTOCYSTS IN RECIPIENT PATIENTS: A PROSPECTIVE RANDOMIZED CONTROL STUDY OF 553 SIBLING DONOR OOCYTES.

To explore whether the adjustment of the redox potential in the culture medium to the similar value found in the follicular fluid of donor oocytes by adding 4 antioxidants every 12 hours can improve the usable and expanded blastocyst formation rates on day-5 and 6 of embryo development This prospective study utilized the sibling oocyte model, was performed between October 2020 and April 2021 and included 47 recipient patients who underwent IVF treatment using donor oocytes. A total of 553 sibling oocytes were split into 2 groups. Group 1: 280 oocytes inseminated and cultured until the blastocyst stage. The oxidation-reduction potential (ORP) of the culture medium for this group was adjusted by adding a combination of antioxidants (EmbryORP) every 12 hour so that the ORP in the culture medium corresponded to the overall ORP levels of follicular fluid of the oocyte donors (86.0±14.8mV). Group 2: 273 oocytes inseminated and cultured in the commercial culture medium without any ORP adjustment. The overall recipient´s age was 39.3±4.4 years. Relative risks and odds ratios as well as the Mantel-Haenszel test to account for confounding factors were calculated. A P-value of P<0.05 was considered significant. No differences in normal fertilization, usable or expanded blastocyst formation rates on day-5 of development were found between the two groups [199 out of 280 (71.0%); 111 out of 199 (55.7%) and 75 out of 199 (37.6%)] vs [196 out of 273 (71.7%); 96 out of 196 (48.9%) and 61 out of 196 (31.1%)] with P-values of P=0.9821; P=0.4021 and P=0.1534, respectively. Significantly better rates for usable and expanded blastocysts were found for group 1 on day-6 of embryo development [20 out of 199 (10.0%) and 18 out of 199 (9.0%)] vs [6 out of 196 (3.06%) and 7 out of 196 (3.5%)] (P=0.0116 and P=0.0266, respectively). The rates of usable and total expanded blastocyst formation on day-5 plus day-6 of development was also statistically higher in group 1 than group 2 (P=0.0387 and P=0.0121, respectively). The results of our study demonstrate for the first time that the adjustment provide a first significant indication of the benefits of media culture supplementation with antioxidants to revert the supraphysiological ORP level in the embryo culture medium of donor oocytes and maintaining it into physiological ORP levels throughout embryo progression in vitro is associated with significantly higher usable and expanded blastocyst rates in recipient patients compared to the conventional embryo culture system.