Optimizing treatment of tauroursodeoxycholic acid to improve embryonic development after in vitro maturation of cumulus-free oocytes in mice

Cumulus-free in vitro maturation (IVM) provides a powerful tool to manipulate immature oocytes, but IVM oocytes lead to poor development after fertilization. Supplementation of the culture medium with tauroursodeoxycholic acid (TUDCA), a bile acid, has been reported to improve the development of embryos derived from in vivo fertilized (IVF) embryos after in vitro culture (IVC) by attenuating endoplasmic reticulum stress. However, it remains unclear if TUDCA can improve development of IVM-IVF embryos. Here, we examined whether TUDCA treatment could improve embryonic development during or after IVM. Immature GV oocytes collected from ovaries of ICR female mice that were free from cumulus cells were subjected to IVM in αMEM containing 5% FBS for 16 h. TUDCA was added to the media at varying concentrations (0–1000 μM) during IVM and IVC. TUDCA treatment during IVM reduced both MII and pronuclear (PN) rates but did not affect blastocyst rates of fertilized embryos. In contrast, TUDCA treatment during IVC significantly increased blastocyst formation rates in a concentration dependent manner. Finally, embryo transfer after TUDCA treatment revealed a significant improvement in the rates of offspring production (15% with 1000 μM TUDCA vs. 6.0% control). These results show that treatment with 1000 μM of TUDCA significantly can improve poor embryonic development of cumulus-free IVM-IVF embryos.