On-chip oocyte denudation from cumulus–oocyte complexes for assisted reproductive therapy†
Human infertility can be treated using assisted reproductive technology (ART) such as intracytoplasmic sperm injection (ICSI). But current ART techniques suffer from multiple cumbersome processes requiring technically skilled personnel. Microfluidics technologies offer unique opportunities to streamline ART procedures, reduce stress imposed upon gametes and embryos, and minimize the operator-to-operator variability. However, there have been no automated and continuous processing systems that can reduce the dependence on well-trained embryologists to obtain ICSI-ready oocytes from patients. In this study, using mouse models, we developed a microfluidic device to denude oocytes from the surrounding cumulus–corona cell mass, facilitating the evaluation of oocyte quality and the injection of sperm. Enzyme-treated cumulus–oocyte complexes pass through a series of jagged-surface constriction microchannels of optimized geometries. The jagged inner wall of constriction channels facilitates stripping off of the cumulus–corona cell mass. Oocytes that were denuded by the device showed comparable fertilization and developmental competence compared with mechanical pipetting. The device developed in this study achieves the automation of a manual process for oocyte denudation in a continuous flow, as well as improving standardization and ease-of-use. Our denudation-on-a-chip approach requires inexpensive and simple equipment, which represents one step forward towards improving the accessibility and affordability of assisted reproductive therapy.