Vitrification of in Vivo-derived Porcine Morulae and Blastocysts Alters Metabolic and Stress Response Pathway Alterations

BackgroundDespite reported promising farrowing rates after non-surgical and surgical transfers of vitrified in vivo-derived porcine morulae and blastocysts (range: 70-75%), their pregnancy loss is yet higher (10-20%) than it is for fresh embryos (< 2.5%). The present study was designed to investigate whether vitrification would affect the transcriptome of porcine morulae and blastocysts, using microarrays and qRT-PCR validation. Material and methods and resultsMorulae and blastocysts were collected from weaned sows (n=13) by laparotomy at Day 6 (Day 0=start of estrus). Of each embryo category, 50 morulae and 50 blastocysts were vitrified (Treatment group) while fresh morulae (n=40) and blastocysts (n=40) acted as control group. After one week of storage, vitrified embryos were cultured in vitrofor 24 h after warming. Non-vitrified morulae (n=40) and blastocysts (n=40), cultured in vitro for 24 h were used as controls. After the in vitro culture period, embryo viability was morphologically assessed. A total of 30 viable embryos per group and embryonic stage(three pools of 10), were subjected to gene expressionanalysis byusing a microarray approach. A fold change cut-off of ±1.5 and a p-unadjusted in vitro.ConclusionIn conclusion, vitrification modified the transcriptome of in vivo-derived porcine morulae and blastocysts, resulting in moderate gene expression changes, which may disturb subsequent embryo development and pregnancy after embryo transfer.