PFT-alpha improves development of porcine embryos in vitro

Any chemical introduced into the environment of an embryo affects its viability and developmental competency. Transcriptional profiling was performed to identify areas of improvement in the porcine in vitro production system at the University of Missouri; this effort revealed that apoptotic transcripts were upregulated in in vitro-cultured porcine embryos compared to their in vivo-derived counterparts. To further identify areas of improvement, differentially expressed genes were subjected to Kegg Pathway Analysis, which revealed upregulation of the p53 pathway in in vitro-produced embryos and a potential target for improvement of the system. Thus, subsequent experiments were conducted to determine if culturing in vitro-produced porcine embryos with p53 inhibitors would improve embryo quality and developmental competency. After in vitro fertilization, presumptive zygotes were placed in either MU4 only or MU4 containing one of three different p53 inhibitors. No difference was observed between control embryos or embryos cultured with pifithrin-beta (PFT-beta) regarding blastocyst formation or cell number (P > 0.05). Embryos cultured with pifithrin-mu (PFT-mu) demonstrated reduced development to the blastocyst stage, particularly if the medium was refreshed on day 3 of culture to reintroduce the compound due to a short half-life (P > 0.05). When cultured with 50 uM pifithrin-alpha (PFT-alpha), development to the blastocyst stage increased (P < 0.05), but total cell number and mRNA transcript abundance of target genes of p53 remained unaltered at the blastocyst stage. Therefore, inhibiting the p53 signaling pathway by including 50 uM PFT-alpha in embryo culture media encourages early porcine embryos to resist stress-induced cell cycle arrest and apoptosis caused by the in vitro culture environment. Lastly, two embryo transfers of embryos cultured with PFT-alpha were performed to assess developmental competency, with normal fetuses at day 45 of gestation.