Evaluating the developmental potential of oocytes and embryos via in situ viscoelastic characterization

IVF procedures account for 1.7% of live births in the USA alone. Early identification of embryos with high implantation potential is required for avoiding clinical complications to the newborn and to the mother that are associated with multiple pregnancy and for shortening time to pregnancy. Previous studies have demonstrated a correlation between the mechanical properties of the embryos and their developmental capacity to implant in the uterus. We developed a multiplate-based device that enables continuous viscoelastic characterization of oocytes and embryos during IVM and preimplantation development under optimal culture conditions. Mechanical assessment is compatible with visual evaluation, which offers non-invasive means of selecting the oocytes and embryos with the highest developmntal potential for transfer. Stress-strain relationships are obtained via controlled pressue system and demonstrated using a bovine model. The response of oocytes and embryos to applied forces fits specific linear viscoelastic models in accordance with their developmental potential. Only high quality GV oocytes that reach MII soften during IVM whereas poor quality oocytes remain stiff. Dynamic changes in embryo mechanics offer means of discriminating between high-potential and low-potential embryos at early stages of preimplantation development. These mechanical profiles are consistent with a decrease in the reproductive potential of aged versus young cows and oocytes obtained from large antral follicles during cold versus hot seasons. Taken together, our assisted reproductive technology has the potential of improving domestic animal breeding schemes and IVF clinical performance in human.