Microrheology of the cumulus-oocyte matrix using optical tweezers

Abstract Optical tweezers have emerged as a powerful, versatile approach for a range of studies in cellular and molecular biology. A particular highlight has been its use for microrheology measurements in miniscule sample volumes. In this study, we demonstrate the application of optical tweezers to investigate the viscosity of the extracellular matrix surrounding mammalian oocytes and determine whether this is associated with oocyte developmental potential. By analysing the motion of a trapped particle, we can quantify the mechanical properties of this matrix, thus overcoming limitations of traditional passive microrheology techniques that rely on free diffusion. We utilise two maturation methods— in vivo and in vitro —to generate oocytes with differing developmental potential. Our findings indicate that oocytes matured in vivo exhibit higher viability post-fertilisation compared to their in vitro counterparts and we establish a positive correlation between extracellular matrix viscosity and oocyte developmental potential. This work demonstrates that optical tweezers are a novel, non-invasive tool for assessing oocyte quality, contributing to valuable insights to the field of reproductive biology.