Abstract
Progression of fertilized mammalian oocytes through cleavage, blastocyst formation and implantation depends on successful implementation of the developmental program, which becomes established during oogenesis. The identification of ooplasmic factors, which are responsible for successful embryo development, is thus crucial in designing possible molecular therapies for infertility intervention. However, systematic evaluation of molecular targets has been hampered by the lack of techniques for efficient delivery of molecules into embryos. We have developed an automated robotic microinjection system for delivering cell impermeable compounds into preimplantation embryos with a high post-injection survival rate. In this paper, we report the performance of the system on microinjection of mouse embryos. Furthermore, using this system we provide the first evidence that recombinant BCL-XL (recBCL-XL) protein is effective in preventing early embryo arrest imposed by suboptimal culture environment. We demonstrate that microinjection of recBCL-XL protein into early-stage embryos repairs mitochondrial bioenergetics, prevents reactive oxygen species (ROS) accumulation, and enhances preimplantation embryo development. This approach may lead to a possible treatment option for patients with repeated in vitro fertilization (IVF) failure due to poor embryo quality.
Highlights
According to the Centre for Disease Control, one in every eight North American couples seeks medical treatment for infertility
In order to determine whether altered levels of Bcl-2 family members accompany embryo arrest in the mouse, we explored if BCL-X protein levels changed in 2-cell stage mouse embryos due to culture in human tubal fluid (HTF) medium
We injected zygotes with BSA dissolved in microinjection buffer, and this did not significantly improve developmental rates (47%; n = 66) or embryo quality (TCN: 6465.5%, cell death index (CDI): 4.260.6; n = 13). These results show that microinjection of the recBCLXL (DTM) protein is capable of restoring developmental competence and improving quality of embryos facing conditions of stress
Summary
According to the Centre for Disease Control, one in every eight North American couples seeks medical treatment for infertility. Embryo quality remains a strong determining factor for predicting the outcome of assisted reproductive technology (ART) [1]. Molecular defects responsible for failed preimplantation development are frequently attributed to poor oocyte quality of unknown etiology. Mathematical modeling of death rates in human preimplantation embryos has suggested that the factors predisposing an embryo to arrest are determined at or even before the zygote stage [2,3]. The ability of the conceptus to pass through the transition from maternal to zygotic control in vitro has been proposed to be a function of the cytoplasmic components of the oocyte with minimal impact of the newly formed zygotic genome [4]. Oocytes must possess cytoplasmic components which accumulate during oogenesis and support development through the blocking stage [5], and these components are lacking or nonfunctional in those embryos that arrest
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
