Warming Oocytes with a Universal Warming Medium and Protocol is as Good as the Company Media and Protocols

Abstract

Background: A universal warming media and protocol would simplify exchange and use of oocytes and embryos between different IVF centres. Aim: The aim of this study was to compare a universal warming medium and protocol (Parmegiani et al, 2014 RBMonline 28, 614-23) with 3 other warming media and protocols which were used with their corresponding vitrification media (2 commercial, one in house) measuring survival (pre and post insemination combined), fertilization and blastocyst rate. Method: This was a prospective study on 300 mature cumulus-free F1 mouse oocytes divided between three vitrification protocols, SAGE™ vitrification (S), RapidVit™ Omni by Vitrolife (V), and the in house ‘MCE-Trehalose’ (M) designed for mouse embryos. Oocytes for each vitrification group (S,V & M) were divided equally to be warmed either by the corresponding warming protocols (S/S, V/V & M/M and or the universal warming protocol (S/U, V/U and M/U). Surviving oocytes were inseminated in vitro with 250,000 motile sperm/ml 2h after warming (18 oocytes were not retrieved post-warm). Results: V/V (25%), V/U (42%) had significantly lower survival than all other groups S/S (72%), S/U (76%), M/M (91%), M/U (82%; P<0.01, Fishers Exact), but no other differences were observed. Fertilization rates [S/S (43%), S/U (40%), V/V (62%), V/U (57%), M/M (59%), M/U (45%)] and blastocyst rates [S/S (61%), S/U (41%), V/V (60%), V/U (75%), M/M (54%), M/U (60%)] did not differ. Conclusion: In conclusion, the universal warming protocol had similar outcomes to the other 3 warming protocols, thus shows promise for warming oocytes vitrified by any vitrification protocol within and between species. Also, demonstrated is that IVF can be used for vitrified oocytes, and thus can provide an option tother than using ICSI clinically, but more studies finding the most suitable clinical media and protocol are needed.