The Expression of Alpha-Fetoprotein in Human Blastocoel Fluid-Conditioned Media In Vitro: A Proof of Concept Study

Alpha-fetoprotein (AFP) is measured during pregnancy in maternal serum to screen for, and in amniotic fluid to test for, neural tube defects. This study aimed to determine whether or not AFP is expressed in blastocoel fluid-conditioned media (BFCM) at the blastocyst stage of embryonic development. For this in vitro study, BFCM was obtained from blastocyst stage embryos following standard embryology laboratory processes. Good quality blastocysts (n = 40) had trophectoderm biopsy for preimplantation genetic testing for aneuploidy (PGT-A) with subsequent blastocyst vitrification and BFCM collection. BFCM samples (n = 40) were analyzed for human AFP protein via an AFP Human ELISA Kit. Statistical analysis was performed with Fisher's exact test. AFP was expressed in 12.5% (5/40) of BFCM samples (range = 1.69-20.5 pg/mL). Of blastocysts with AFP in BFCM, 80% (4/5) had aneuploid PGT-A results; of blastocysts with no AFP in BFCM, 57% (20/35) had aneuploid PGT-A results, with no difference between groups (<i>p</i> = 0.63). Our study demonstrates AFP expression in BFCM. To our knowledge, this is the first study to report the detection of AFP at the embryonic blastocyst stage in vitro. Future studies are needed and underway to determine whether assessment of AFP at the embryonic stage can improve embryo transfer outcomes.